LM5175 [TI]
42V 宽输入电压 4 开关同步降压/升压控制器;型号: | LM5175 |
厂家: | TEXAS INSTRUMENTS |
描述: | 42V 宽输入电压 4 开关同步降压/升压控制器 开关 控制器 |
文件: | 总41页 (文件大小:1791K) |
中文: | 中文翻译 | 下载: | 下载PDF数据表文档文件 |
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LM5175
ZHCSDH1A –OCTOBER 2015–REVISED MAY 2016
LM5175 42V 宽 VIN 同步 4 开关 降压 - 升压控制器
1 特性
3 说明
1
•
单电感降压-升压控制器,用于升压/降压 DC/DC 转
换
LM5175 是一款同步四开关降压-升压 DC/DC 控制
器,能够将输出电压稳定在输入电压、高于输入电压或
者低于输入电压的某一电压值上。LM5175 具有 3.5V
至 42V 的宽输入电压范围(最大值为 60V),支持各
类 应用。
•
•
•
•
•
•
•
宽 VIN 范围:3.5V 至 42V,最大值为 60V
灵活的 VOUT 范围:0.8V 至 55V
VOUT 短路保护
高效降压-升压转换
可调开关频率
LM5175 在降压和升压工作模式下均采用电流模式控
制,以提供出色的负载和线路调节性能。开关频率可通
过外部电阻进行编程,并且可与外部时钟信号同步。
可选频率同步和抖动
集成 2A 金属氧化物半导体场效应晶体管
(MOSFET) 栅极驱动器
该器件还 具有 可编程的软启动功能,并且提供 诸如
逐周期电流限制、输入欠压锁定 (UVLO)、输出过压保
护 (OVP) 和热关断等各类保护特性。此外,LM5175
特有 可选择的连续导通模式 (CCM) 或断续导通模式
(DCM)、可选平均输入或输出电流限制、可降低峰值电
磁干扰 (EMI) 的可选扩展频谱、以及应对持续过载情
况的可选断续模式保护。
•
•
•
•
•
逐周期电流限制和可选断续模式
可选输入或输出平均电流限制
可编程的输入欠压闭锁 (UVLO) 和软启动
电源正常和输出过压保护
可利用脉冲跳跃来选择连续导通模式 (CCM) 或断
续导通模式 (DCM)
•
采用 HTSSOP-28 和 QFN-28 封装
器件信息
订货编号
LM5175PWP
LM5175RHF
封装
HTSSOP-28
QFN-28
封装尺寸
9.7mm x 4.4mm
4.0mm x 5.0mm
2 应用
•
•
•
•
•
汽车起停系统
备用电池和超级电容充电
工业 PC 用电源
USB 供电
LED 照明
4 简化电路原理图
VIN
VCC
VOUT
BOOT1
HDRV1
EN/UVLO
Enable
Power Good
PGOOD
SS
SW1
LDRV1
SLOPE
CS
CSG
LM5175
RT/SYNC
LDRV2
COMP
SW2
AGND
PGND
VCC
BOOT2
HDRV2
VOSNS
VCC
Copyright © 2016, Texas Instruments Incorporated
1
An IMPORTANT NOTICE at the end of this data sheet addresses availability, warranty, changes, use in safety-critical applications,
intellectual property matters and other important disclaimers. PRODUCTION DATA.
English Data Sheet: SNVSA37
LM5175
ZHCSDH1A –OCTOBER 2015–REVISED MAY 2016
www.ti.com.cn
目录
8.3 Feature Description................................................. 13
8.4 Device Functional Modes........................................ 19
Application and Implementation ........................ 20
9.1 Application Information............................................ 20
9.2 Typical Application .................................................. 20
1
2
3
4
5
6
7
特性.......................................................................... 1
应用.......................................................................... 1
说明.......................................................................... 1
简化电路原理图........................................................ 1
修订历史记录 ........................................................... 2
Pin Configuration and Functions......................... 3
Specifications......................................................... 5
7.1 Absolute Maximum Ratings ...................................... 5
7.2 ESD Ratings.............................................................. 5
7.3 Recommended Operating Conditions....................... 5
7.4 Thermal Information.................................................. 6
7.5 Electrical Characteristics........................................... 6
7.6 Typical Characteristics.............................................. 9
Detailed Description ............................................ 12
8.1 Overview ................................................................. 12
8.2 Functional Block Diagram ....................................... 13
9
10 Power Supply Recommendations ..................... 27
11 Layout................................................................... 27
11.1 Layout Guidelines ................................................. 27
11.2 Layout Example .................................................... 28
12 器件和文档支持 ..................................................... 29
12.1 文档支持................................................................ 29
12.2 社区资源................................................................ 29
12.3 商标....................................................................... 29
12.4 静电放电警告......................................................... 29
12.5 Glossary................................................................ 29
13 机械、封装和可订购信息....................................... 29
8
5 修订历史记录
Changes from Original (October 2015) to Revision A
Page
•
•
•
•
•
•
•
•
•
已添加 QFN-28 封装............................................................................................................................................................... 1
已添加 LM5175RHF 信息 ....................................................................................................................................................... 1
Added RHF package .............................................................................................................................................................. 3
Added QFN pins .................................................................................................................................................................... 4
Changed first plus to minus ................................................................................................................................................. 18
Changed all 1.22 V to 1.23 V .............................................................................................................................................. 19
Changed equation ............................................................................................................................................................... 23
Changed equation ............................................................................................................................................................... 25
Changed equation ............................................................................................................................................................... 25
2
Copyright © 2015–2016, Texas Instruments Incorporated
LM5175
www.ti.com.cn
ZHCSDH1A –OCTOBER 2015–REVISED MAY 2016
6 Pin Configuration and Functions
HTSSOP-28
PWP Package
Top View
EN/UVLO
VIN
1
28
27
26
25
24
23
22
21
20
19
18
17
16
15
SW1
2
HDRV1
BOOT1
LDRV1
BIAS
VISNS
MODE
DITH
3
4
5
RT
6
VCC
SLOPE
SS
7
PGND
LDRV2
BOOT2
HDRV2
SW2
LM5175
HTSSOP-28
8
COMP
AGND
FB
9
10
11
12
13
14
VOSNS
ISNS(œ)
ISNS(+)
PGOOD
CS
CSG
QFN-28
RHF Package
Top View
MODE
DITH
RT
1
2
3
4
5
6
7
8
22
LDRV1
BIAS
21
20
19
18
17
16
15
VCC
SLOPE
SS
PGND
LDRV2
BOOT2
HDRV2
SW2
LM5175
QFN-28
COMP
AGND
FB
Copyright © 2015–2016, Texas Instruments Incorporated
3
LM5175
ZHCSDH1A –OCTOBER 2015–REVISED MAY 2016
www.ti.com.cn
Pin Functions
PIN
DESCRIPTION
NAME
HTSSOP
QFN
Enable pin. For EN/UVLO < 0.4 V, the LM5175 is in a low current shutdown mode. For 0.7 V <
EN/UVLO < 1.23 V, the controller operates in standby mode in which the VCC regulator is enabled but
the PWM controller is not switching. For EN/UVLO > 1.23 V, the PWM function is enabled, provided
VCC exceeds the VCC UV threshold.
EN/UVLO
1
26
VIN
2
3
27
28
The input supply pin to the IC. Connect VIN to a supply voltage between 3.5 V and 42 V.
VIN sense input. Connect to the input capacitor.
VISNS
Mode = GND, DCM, Hiccup Disabled
Mode = 1.00 V, DCM, Hiccup Enabled
Mode = 1.85 V, CCM, Hiccup Enabled
Mode = VCC, CCM, Hiccup Disabled
(Set RMODE resistor to GND = 0 Ω)
(Set RMODE resistor to GND = 49.9 kΩ)
(Set RMODE resistor to GND = 93.1 kΩ)
(Set RMODE resistor to VCC = 0 Ω)
MODE
4
1
A capacitor connected between the DITH pin and AGND is charged and discharged with a 10 uA
current source. As the voltage on the DITH pin ramps up and down the oscillator frequency is
modulated between –5% and +5% of the nominal frequency set by the RT resistor. Grounding the
DITH pin will disable the dithering feature. In the external Sync mode, the DITH pin voltage is ignored.
DITH
5
6
2
3
Switching frequency programming pin. An external resistor is connected to the RT/SYNC pin and
AGND to set the switching frequency. This pin can also be used to synchronize the PWM controller to
an external clock.
RT/SYNC
A capacitor connected between the SLOPE pin and AGND provides the slope compensation ramp for
stable current mode operation in both buck and boost mode.
SLOPE
SS
7
8
4
5
6
7
8
9
Soft-start programming pin. A capacitor between the SS pin and AGND pin programs soft-start time.
Output of the error amplifier. An external RC network connected between COMP and AGND
compensates the regulator feedback loop.
COMP
AGND
FB
9
10
11
12
Analog ground of the IC.
Feedback pin for output voltage regulation. Connect a resistor divider network from the output of the
converter to the FB pin.
VOSNS
VOUT sense input. Connect to the output capacitor.
Input or Output Current Sense Amplifier inputs. An optional current sense resistor connected between
ISNS(+) and ISNS(–) can be located either on the input side or on the output side of the converter. If
the sensed voltage across the ISNS(+) and ISNS(-) pins reaches 50 mV, a slow Constant Current (CC)
control loop becomes active and starts discharging the soft-start capacitor to regulated the drop across
ISNS(+) and ISNS(-) to 50 mV. Short ISNS(+) and ISNS(-) together to disable this feature.
ISNS(–)
ISNS(+)
13
14
10
11
The negative or ground input to the PWM current sense amplifier. Connect directly to the low-side
(ground) of the current sense resistor.
CSG
15
16
17
12
13
14
CS
The positive input to the PWM current sense amplifier.
Power Good open drain output. PGOOD is pulled low when FB is outside a 0.8 V ±10% regulation
window.
PGOOD
SW2
SW1
18
28
15
25
The boost and the buck side switching nodes respectively.
HDRV2
HDRV1
19
27
16
24
Output of the high-side gate drivers. Connect directly to the gates of the high-side MOSFETs.
BOOT2
BOOT1
20
26
17
23
An external capacitor is required between the BOOT1, BOOT2 pins and the SW1, SW2 pins
respectively to provide bias to the high-side MOSFET gate drivers.
LDRV2
LDRV1
21
25
18
22
Output of the low-side gate drivers. Connect directly to the gates of the low-side MOSFETs.
PGND
VCC
22
23
19
20
Power ground of the IC. The high current ground connection to the low-side gate drivers.
Output of the VCC bias regulator. Connect capacitor to ground.
Optional input to the VCC bias regulator. Powering VCC from an external supply instead of VIN can
reduce power loss at high VIN. For VBIAS > 8 V, the VCC regulator draws power from the BIAS pin. The
BIAS pin voltage must not exceed 40 V.
BIAS
24
-
21
-
PowerPAD
™
The PowerPAD should be soldered to the analog ground. If possible, use thermal vias to connect to a
PCB ground plane for improved power dissipation.
4
Copyright © 2015–2016, Texas Instruments Incorporated
LM5175
www.ti.com.cn
ZHCSDH1A –OCTOBER 2015–REVISED MAY 2016
7 Specifications
7.1 Absolute Maximum Ratings(1)
MIN
–0.3
–0.3
–0.3
–1
MAX
60
UNIT
VIN, EN/UVLO, VISNS, VOSNS, ISNS(+), ISNS(–)
BIAS
40
FB, SS, DITH, RT/SYNC, SLOPE, COMP
SW1, SW2
3.6
60
SW1, SW2 (20 ns transient)
VCC, MODE, PGOOD
–3.0
–0.3
–0.3
–0.3
–0.3
–0.3
–0.3
–40
-65
65
8.5
8.5
8.5
8.5
68
V
LDRV1, LDRV2
BOOT1, HDRV1 with respect to SW1
BOOT2, HDRV2 with respect to SW2
BOOT1, BOOT2
CS, CSG
0.3
150
150
Operating junction temperature
Storage temperature, Tstg
°C
(1) Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings
only, which do not imply functional operation of the device at these or any other conditions beyond those indicated under Recommended
Operating Conditions. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
7.2 ESD Ratings
VALUE
±2000
±750
UNIT
Human body model (HBM) ESD stress voltage(2)
Charged device model (CDM) ESD stress voltage(3)
(1)
VESD
V
(1) Electrostatic discharge (ESD) to measure device sensitivity and immunity to damage caused by assembly line electrostatic discharges
into the device.
(2) Level listed above is the passing level per ANSI/ESDA/JEDEC JS-001. JEDEC document JEP155 states that 500 V HBM allows safe
manufacturing with a standard ESD control process.
(3) Level listed above is the passing level per EIA-JEDEC JESD22-C101. JEDEC document JEP157 states that 250 V CDM allows safe
manufacturing with a standard ESD control process.
7.3 Recommended Operating Conditions
over operating free-air temperature range (unless otherwise noted)(1)
MIN
3.5
8
NOM
MAX
42
UNIT
VIN
Input voltage range
BIAS
Bias supply voltage range
Output voltage range
36
VOUT
0.8
0
55
V
EN/UVLO
Enable voltage range
42
ISNS(+), ISNS(-)
Average current sense common mode range
Operating temperature range(2)
Operating frequency range
0
55
TJ
–40
100
125
600
°C
Fsw
kHz
(1) Recommended Operating Conditions are conditions under the device is intended to be functional. For specifications and test conditions,
see Electrical Characteristics .
(2) High junction temperatures degrade operating lifetimes. Operating lifetime is de-rated for junction temperatures greater than 125°C.
Copyright © 2015–2016, Texas Instruments Incorporated
5
LM5175
ZHCSDH1A –OCTOBER 2015–REVISED MAY 2016
www.ti.com.cn
7.4 Thermal Information
LM5175
THERMAL METRIC(1)
HTSSOP
28 PINS
33.1
QFN
28 PINS
34.7
26.6
6.3
UNIT
RθJA
Junction-to-ambient thermal resistance
RθJC(top) Junction-to-case (top) thermal resistance
17.7
RθJB
ψJT
Junction-to-board thermal resistance
14.9
°C/W
Junction-to-top characterization parameter
Junction-to-board characterization parameter
0.4
0.3
ψJB
14.7
6.2
RθJC(bot) Junction-to-case (bottom) thermal resistance
1.1
2.0
(1) For more information about traditional and new thermal metrics, see the IC Package Thermal Metrics application report, SPRA953.
7.5 Electrical Characteristics
Typical values correspond to TJ = 25°C. Minimum and maximum limits apply over the –40°C to 125°C junction temperature
range unless otherwise stated. VIN = 24 V unless otherwise stated.(1)
PARAMETER
TEST CONDITION
MIN
TYP
MAX
UNIT
SUPPLY VOLTAGE (VIN
)
VIN
IQ
Operating input voltage
VIN shutdown current
VIN standby current
VIN operating current
3.5
42
10
2
V
VEN/UVLO = 0 V
1.4
0.7
µA
VEN/UVLO = 1.1 V, non-switching
VEN/UVLO = 2 V, VFB = 0.9 V
1.65
4
mA
VCC
VVCC(VIN)
VUV(VCC)
Regulation voltage
VBIAS = 0 V, VCC open
VCC increasing
6.95
3.11
7.35
3.27
160
7.88
3.43
V
VCC Undervoltage lockout
Undervoltage hysteresis
VCC current limit
mV
mA
Ω
IVCC
VVCC = 0 V
65
ROUT(VCC)
BIAS
VCC regulator output impedance
IVCC = 30 mA, VIN = 3.5 V
9.3
8
16
VBIAS(SW)
EN/UVLO
VEN(STBY)
IEN(STBY)
VEN(OP)
ΔIHYS(OP)
SS
BIAS switchover voltage
VIN = 24 V
7.25
8.75
V
Standby threshold
EN/UVLO rising
VEN/UVLO = 1.1 V
EN/UVLO rising
VEN/UVLO = 2.4 V
0.55
1
0.79
2
0.97
3
V
µA
V
Standby source current
Operating threshold
1.17
1.5
1.23
3.5
1.29
5.5
Operating hysteresis current
µA
ISS
Soft-start pull up current
SS clamp voltage
FB to SS offset
VSS = 0 V
SS open
VSS = 0 V
4.30
5.65
1.27
-15
7.25
µA
V
VSS(CL)
VFB - VSS
mV
EA (ERROR AMPLIFIER)
VREF
Feedback reference voltage
Error amplifier gm
FB = COMP
0.788
0.800
1.27
280
20
0.812
V
gmEA
mS
µA
ISINK/ISOURCE COMP sink/source current
VFB=VREF ± 300 mV
ROUT
Amplifier output resistance
Unity gain bandwidth
MΩ
MHz
nA
BW
2
IBIAS(FB)
FREQUENCY
fSW(1)
Feedback pin input bias current
FB in regulation
100
Switching Frequency 1
Switching Frequency 2
RT = 133 kΩ
RT = 47 kΩ
180
430
200
500
220
565
kHz
fSW(2)
(1) All minimum and maximum limits are specified by correlating the electrical characteristics to process and temperature variations and
applying statistical process control.
6
Copyright © 2015–2016, Texas Instruments Incorporated
LM5175
www.ti.com.cn
ZHCSDH1A –OCTOBER 2015–REVISED MAY 2016
Electrical Characteristics (continued)
Typical values correspond to TJ = 25°C. Minimum and maximum limits apply over the –40°C to 125°C junction temperature
range unless otherwise stated. VIN = 24 V unless otherwise stated.(1)
PARAMETER
TEST CONDITION
MIN
TYP
MAX
UNIT
DITHER
IDITHER
Dither source/sink current
Dither high threshold
Dither low threshold
10.5
1.27
1.16
µA
V
VDITHER
SYNC
VSYNC
Sync input high threshold
Sync input low threshold
Sync input pulse width
2.1
75
V
1.2
PWSYNC
500
ns
CURRENT LIMIT
VCS(BUCK)
Buck current limit threshold (Valley)
VIN = VVISNS = 24 V, VVOSNS = 12 V,
VSLOPE = 0 V, TJ = 25°C
53.2
119
76
98
mV
µA
VCS(BOOST)
Boost current limit threshold (Peak)
VIN = VVISNS = 12 V, VVOSNS = 18 V,
VSLOPE = 0 V, TJ = 25°C
170
-75
221
IBIAS(CS/CSG)
CS/CSG pin bias current
VCS = VCSG = 0 V
VCS = VCSG = 0 V
IOFFSET(CS/CS CSG pin bias current
G)
14
57
CONSTANT CURRENT LOOP
VSNS
Average current loop regulation target
VISNS(-) = 24 V, sweep ISNS(+), VSS
0.8 V
=
43
50
7
mV
µA
ISNS
Gm
ISNS(+)/ISNS(–) pin bias currents
gm of soft-start pull down amplifier
VISNS(+) = VISNS(–) = VIN = 24 V
VISNS(+)–VISNS(–) = 55 mV, VSS = 0.5
V
1
mS
SLOPE
ISLOPE
Buck adaptive slope current
Boost adaptive slope current
Slope compensation amplifier gm
VIN = VVINSNS = 24 V, VVOSNS = 12 V,
VSLOPE = 0 V
24
13
30
35
21
µA
VIN = VVINSNS = 12 V, VVOSNS = 18 V,
VSLOPE = 0 V
17
2
gmSLOPE
MODE
µS
µA
V
IMODE
Source current out of MODE pin
DCM with hiccup threshold
CCM with hiccup threshold
CCM no hiccup threshold
17
0.60
1.18
2.22
20
0.7
23
0.76
1.38
2.6
VDCM_HIC
VCCM_HIC
VCCM
1.28
2.4
Copyright © 2015–2016, Texas Instruments Incorporated
7
LM5175
ZHCSDH1A –OCTOBER 2015–REVISED MAY 2016
www.ti.com.cn
Electrical Characteristics (continued)
Typical values correspond to TJ = 25°C. Minimum and maximum limits apply over the –40°C to 125°C junction temperature
range unless otherwise stated. VIN = 24 V unless otherwise stated.(1)
PARAMETER
TEST CONDITION
MIN
TYP
MAX
UNIT
PGOOD
VPGD
PGOOD trip threshold for falling FB
PGOOD trip threshold for rising FB
Hysteresis
Measured with respect to VREF
Measured with respect to VREF
–9
10
%
%
1.6
%
ILEAK(PGD)
ISINK(PGD)
OUTPUT OVP
VOVP
PGOOD leakage current
PGOOD sink current
100
6.5
nA
mA
VPGOOD = 0.4 V
At the FB pin
2
4.2
Output overvoltage threshold
Hysteresis
0.86
21
V
mV
NMOS DRIVERS
IHDRV1,2
Driver peak source current
VBOOT - VSW = 7 V
VBOOT - VSW = 7 V
1.8
2.2
Driver peak sink current
A
ILDRV1,2
Driver peak source current
Driver peak sink current
1.8
2.2
RHDRV1,2
Driver pull up resistance
VBOOT - VSW = 7 V
VBOOT - VSW = 7 V
HDRV1,2 shut off
1.9
Ω
Driver pull down resistance
BOOT1,2 to SW1,2 UVLO threshold
BOOT1,2 to SW1,2 UVLO hysteresis
1.3
VUV(BOOT1,2)
2.73
280
V
HDRV1,2 start switching
mV
BOOT1,2 to SW1,2 threshold for refresh
pulse
4.45
V
RLDRV1,2
Driver pull up resistance
IDRV1,2 = 0.1 A
IDRV1,2 = 0.1 A
2
1.5
55
Ω
Driver pull down resistance
tDT1
tDT2
Dead time HDRV1,2 off to LDRV1,2 on
Dead time LDRV1,2 off to HDRV1,2 on
ns
°C
55
THERMAL SHUTDOWN
TSD
Thermal shutdown temperature
Thermal shutdown hysteresis
165
15
TSD(HYS)
8
Copyright © 2015–2016, Texas Instruments Incorporated
LM5175
www.ti.com.cn
ZHCSDH1A –OCTOBER 2015–REVISED MAY 2016
7.6 Typical Characteristics
At TA = 25°C, unless otherwise stated.
100
95
90
85
80
99
98
97
96
95
94
93
VIN=6V
VIN=12V
VIN=24V
5
10
15
20
25
30
35
40
45
0
1
2
3
4
5
6
VIN (V)
LOAD CURRENT (A)
D009
D008
VOUT=12 V
IOUT=3 A
Fsw=300 kHz
L1=4.7 μH
VOUT =12 V
Fsw=300 kHz
L1=4.7 μH
Figure 1. Efficiency vs VIN
Figure 2. Efficiency vs Load
600
8
6
4
2
0
500
400
300
200
100
0
2
4
6
8
10
12
14
16
18
0
50
100
150
RT (kW)
200
250
300
VIN (V)
D002
D004
Figure 4. VCC vs VIN
Figure 3. Oscillator Frequency
1
0.8
0.6
0.4
0.2
0
2.4
2.2
2
1.8
1.6
1.4
BIAS = 12V
BIAS = 0V
BIAS = 12V
BIAS = 0V
0
5
10
15
20
25
30
35
40
45
0
5
10
15
20
25
30
35
40
45
VIN (V)
VIN (V)
D006
D007
Figure 5. IIN Standby
Figure 6. IIN Operating vs VIN
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Typical Characteristics (continued)
At TA = 25°C, unless otherwise stated.
4
1.30
1.26
1.22
1.18
1.14
1.10
3.2
2.4
1.6
0.8
0
-40 °C
25 °C
125 °C
0
5
10
15
20
25
30
35
40
45
-40
-20
0
20
40
60
80
100 120 140
VIN (V)
TEMPERATURE (°C)
D010
D013
Figure 7. IIN Shutdown vs VIN
Figure 8. ENABLE/UVLO Rising Threshold vs Temperature
110
100
90
200
190
180
170
160
150
140
80
70
60
50
-40
-20
0
20
40
60
80
100 120 140
-40
-20
0
20
40
60
80
100 120 140
TEMPERATURE (èC)
TEMPERATURE (°C)
D012
D011
Figure 9. Buck Current Limit vs Temperature
Figure 10. Boost Current Limit vs Temperature
0.805
{í1 (20ë/div)
0.803
0.801
0.799
0.797
0.795
{í2 (10ë/div)
ëhÜÇ (200më/div ac)
L[ (5!/div)
5 µs/div
-40
-20
0
20
40
60
80
100 120 140
VOUT=12 V
VIN=24 V
TEMPERATURE (°C)
D014
Figure 12. Forced CCM Operation (Buck)
Figure 11. VREF vs Temperature
10
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Typical Characteristics (continued)
At TA = 25°C, unless otherwise stated.
{í1 (20ë/div)
{í2 (10ë/div)
{í1 (20ë/div)
{í2 (10ë/div)
ëhÜÇ (200më/div ac)
L[ (5!/div)
ëhÜÇ (200më/div ac)
L[ (5!/div)
5 µs/div
500 µs/div
500 µs/div
5 µs/div
VOUT=12 V
VIN=6 V
VOUT=12 V
VIN=12 V
Figure 13. Forced CCM Operation (Boost)
Figure 14. Forced CCM Operation (Buck-Boost)
ëhÜÇ (500më/div)
ëhÜÇ (500 më/div ac)
L[ (5!/div)
L[ (5!/div)
500 µs/div
VIN=6 V
VOUT=12 V
Load 2A to 4A
VIN=24 V
VOUT=12 V
Load 2A to 4A
Figure 16. Load Step (Boost)
Figure 15. Load Step (Buck)
ëhÜÇ (500më/div)
L[ (5!/div)
ëhÜÇ (1ë/div)
ꢀhat (1ë/div)
ëLb (10ë/div)
L[ (5!/div)
5ms/div
VIN=12 V
VOUT=12 V
Load 2A to 4A
VIN=8 V to 24 V
VOUT=12 V
IOUT=1A
Figure 17. Load Step (Buck-Boost)
Figure 18. Line Transient
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Typical Characteristics (continued)
At TA = 25°C, unless otherwise stated.
ëhÜÇ (5ë/div)
welease
hverload
Iiccup
L[ (5!/div)
20ms/div
VIN=24 V
VOUT=12 V
Hiccup Enabled
Figure 19. Hiccup Mode Current Limit
8 Detailed Description
8.1 Overview
The LM5175 is a wide input voltage four-switch buck-boost controller IC with integrated drivers for N-channel
MOSFETs. It operates in the buck mode when VIN is greater than VOUT and in the boost mode when VIN is less
than VOUT. When VIN is close to VOUT, the device operates in a proprietary transition buck or boost mode. The
control scheme provides smooth operation for any input/output combination within the specified operating range.
The buck or boost transition control scheme provides a low ripple output voltage when VIN equals VOUT without
compromising the efficiency.
The LM5175 integrates four N-Channel MOSFET drivers including two low-side drivers and two high-side drivers,
eliminating the need for external drivers or floating bias supplies. The internal VCC regulator supplies internal
bias rails as well as the MOSFET gate drivers. The VCC regulator is powered either from the input voltage
through the VIN pin or from the output or an external supply through the BIAS pin for improved efficiency.
The PWM control scheme is based on valley current mode control for buck operation and peak current mode
control for boost operation. The inductor current is sensed through a single sense resistor in series with the low-
side MOSFETs. The sensed current is also monitored for cycle-by-cycle current limit. The behavior of the
LM5175 during an overload condition is dependent on the MODE pin programming (see MODE Pin
Configuration). If hiccup mode fault protection is selected, the controller turns off after a fixed number of
switching cycles in cycle-by-cycle current limit and restarts after another fixed number of clock cycles. The hiccup
mode reduces the heating in the power components in a sustained overload condition. If hiccup mode is disabled
through the MODE pin, the controller remains in a cycle-by-cycle current limit condition until the overload is
removed. The MODE pin also selects continuous conduction mode (CCM) for noise sensitive applications or
discontinuous conduction mode (DCM) for higher light load efficiency.
In addition to the cycle-by-cycle current limiting, the LM5175 also provides an optional average current regulation
loop that can be configured for either input or output current limiting. This is useful for battery charging or other
applications where a constant current behavior may be required.
The soft-start time of LM5175 is programmed by a capacitor connected to the SS pin to minimize the inrush
current and overshoot during startup.
The precision EN/UVLO pin supports programmable input undervoltage lockout (UVLO) with hysteresis. The
output overvoltage protection (OVP) feature turns off the high-side drivers when the voltage at the FB pin is 7.5%
above the nominal 0.8-V VREF. The PGOOD output indicates when the FB voltage is inside a ±10% regulation
window centered at VREF
.
12
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8.2 Functional Block Diagram
VIN
BIAS
3.5 µA
+
-
EN/UVLO
VCC
1.23 V
OPERATING
STANDBY
EN & BIAS
LOGIC
1.5 µA
0.7 V
THERMAL
SHUTDOWN
+
-
45 mV
1.2 V
PGOOD
-
5 µA
SS
0.88 V
OV
-
+
-
+
0.86 V
ISNS(+)
ISNS(-)
+
-
FB
0.72 V
+
-
+
1 mA/V
CONSTANT
CURRENT LOOP
BOOT1
HDRV1
3.3 V
GM ERROR
AMPLIFIER
PWM
COMPARATOR
1.6 V
0.8 V
+
+
SS
FB
+
-
SW1
-
VCC
LDRV1
COMP
CS
AMPLIFIER
CLK
BUCK-BOOST CONTROLLER
LOGIC
BOOT2
HDRV2
CS
+
A=5
ꢀ
ILIMIT
COMPARATOR
CSG
-
SW2
+
-
VCC
LDRV2
VISNS
VOSNS
SLOPE
V
ILIM
SLOPE
COMP
CCM/DCM
&
MODE
HICCUP CURRENT
LIMIT
RT/SYNC
DITH
OSC/SYNC
CLK
PGND
AGND
Copyright © 2016, Texas Instruments Incorporated
8.3 Feature Description
8.3.1 Fixed Frequency Valley/Peak Current Mode Control with Slope Compensation
The LM5175 implements a fixed frequency current mode control of both the buck and boost switches. The output
voltage, scaled down by the feedback resistor divider, appears at the FB pin and is compared to the internal
reference (VREF) by an internal error amplifier. The error amplifier produces an error voltage by driving the COMP
pin. An adaptive slope compensation signal based on VIN, VOUT, and the capacitor at the SLOPE pin is added to
the current sense signal measured across the CS and CSG pins. The result is compared to the COMP error
voltage by the PWM comparator.
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Feature Description (continued)
The LM5175 regulates the output using valley current mode control in buck mode and peak current mode control
in boost mode. For valley current mode control, the high-side buck MOSFET controlled by HDRV1 is turned on
by the PWM comparator at the valley of the inductor ripple current and turned off by the oscillator clock signal.
Valley current mode control is advantageous for buck converters where the PWM controller must resolve very
short on-times. For peak current mode control in the boost mode, the low-side boost MOSFET controlled by
LDRV2 is turned on by the clock signal in each switching cycle and turned off by the PWM comparator at the
peak of the inductor ripple current.
The low-side gate drive LDRV1, complementary to the HDRV1 drive signal, controls the synchronous rectification
MOSFET of the buck stage. The high-side gate drive HDRV2, complementary to the low-side gate drive LDRV2,
controls the high-side synchronous rectifier of the boost stage. For operation with VIN close to VOUT, the LM5175
uses a proprietary buck or boost transition scheme to achieve smooth, low ripple transition zone behavior.
Peak and valley current mode controllers require slope compensation for stable current loop operation at duty
cycle greater than 50% in peak current mode control and less than 50% in valley current mode control. The
LM5175 provides a SLOPE pin to program optimum slope for any VIN and VOUT combination using an external
capacitor.
8.3.2 VCC Regulator and Optional BIAS Input
The VCC regulator provides a regulated 7.5-V bias supply to the gate drivers. When EN/UVLO is above the 0.7-
V (typical) standby threshold, the VCC regulator is turned on. For VIN less than 7.5 V, the VCC voltage tracks VIN
with a small voltage drop as shown in Figure 4. If the EN/UVLO input is above the 1.23 V operating threshold
and VCC exceeds the 3.3 V (typical) VCC UV threshold, the controller is enabled and switching begins.
The VCC regulator draws power from VIN when there is no supply voltage connected to the BIAS pin. If the BIAS
pin is connected to an external voltage source that exceeds VCC by one diode drop, the VCC regulator draws
power from the BIAS input instead of VIN. Connecting the BIAS pin to VOUT in applications with VOUT greater than
8.5 V improves the efficiency of the regulator in the buck mode. The BIAS pin voltage should not exceed 36 V.
For low VIN operation, ensure that the VCC voltage is sufficient to fully enhance the MOSFETs. Use an external
bias supply if VIN dips below the voltage required to sustain the VCC voltage. For these conditions, use a series
blocking diode between the input supply and the VIN pin (Figure 20). This prevents VCC from back-feeding into
VIN through the body diode of the VCC regulator.
A 1-µF capacitor to PGND is required to supply the VCC regulator load transients.
Series Blocking
Diode
VIN
VIN
CVIN
LM5175
Optional
Bias Supply/
VOUT
BIAS
CBIAS
VCC
CVCC
Copyright © 2016, Texas Instruments Incorporated
Figure 20. VCC Regulator
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Feature Description (continued)
8.3.3 Enable/UVLO
The LM5175 has a dual function enable and undervoltage lockout (UVLO) circuit. The EN/UVLO pin has three
distinct voltage ranges: shutdown, standby, and operating (see Shutdown, Standby, and Operating Modes).
When the EN/UVLO pin is below the standby threshold (0.7 V typical), the converter is held in a low power
shutdown mode. When EN/UVLO voltage is greater than the standby threshold but less than the 1.23 V
operating threshold, the internal bias rails and the VCC regulator are enabled but the soft-start (SS) pin is held
low and the PWM controller is disabled. A 1.5 µA pull-up current is sourced out of the EN/UVLO pin in standby
mode to provide hysteresis between the shutdown mode and the standby mode. When EN/UVLO is greater than
the 1.23 V operating threshold, the controller commences operation if VCC is above VCC UV threshold (3.3 V). A
hysteresis current of 3.5 µA is sourced into the EN/UVLO pin when the EN/UVLO input exceeds the 1.23 V
operation threshold to provide hysteresis that prevents on/off chattering in the presence of noise with a slowly
changing input voltage.
The VIN undervoltage lockout turn-on threshold is typically set by a resistor divider from the VIN pin to AGND with
the mid-point of the divider connected to EN/UVLO. The turn-on threshold VINUV is calculated using Equation 1
where RUV2 is the upper resistor and RUV1 is the lower resistor in the EN/UVLO resistor divider:
≈
’
÷
◊
RUV2
RUV1
V
= 1.23 V ì 1+
-RUV2 ì1.5 mA
∆
IN(UV)
«
(1)
The hysteresis between the UVLO turn-on threshold and turn-off threshold is set by the upper resistor in the
EN/UVLO resistor divider and is given by:
DVHYS(UV) = 3.5 mA ìRUV2
(2)
VIN
LM5175
RUV2
EN/UVLO
RUV1
Copyright © 2016, Texas Instruments Incorporated
Figure 21. UVLO Threshold Programming
8.3.4 Soft-Start
The LM5175 soft-start time is programmed using a soft-start capacitor from the SS pin to AGND. When the
converter is enabled, an internal 5-µA current source charges the soft-start capacitor. When the SS pin voltage is
below the 0.8-V feedback reference voltage VREF, the soft-start pin controls the regulated FB voltage. Once SS
exceeds VREF, the soft-start interval is complete and the error amplifier is referenced to VREF. The soft-start time
is given by Equation 3:
CSS ì 0.8 V
tss
=
5 mA
(3)
The soft-start capacitor is internally discharged when the converter is disabled because of EN/UVLO falling
below the operation threshold or VCC falling below the VCC UV threshold. The soft-start pin is also discharged
when the converter is in hiccup mode current limiting or in thermal shutdown. When average input or output
current limiting is active, the soft-start capacitor is discharged by the constant current loop transconductance
(gm) amplifier to limit either input or output current.
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Feature Description (continued)
8.3.5 Overcurrent Protection
The LM5175 provides cycle-by-cycle current limit to protect against overcurrent and short circuit conditions. In
buck operation, the sensed valley voltage across the CSG and CS pins is limited to 76 mV. The high-side buck
switch skips a cycle if the sensed voltage does not fall below this threshold during the buck switch off time. In
boost operation, the maximum peak voltage across CS and CSG is limited to 170mV. If the peak current in the
low-side boost switch causes the CS pin to exceed this threshold voltage, the boost switch is turned off for the
remainder of the clock cycle.
Applying the appropriate voltage to the MODE pin of the LM5175 enables hiccup mode fault protection (see
MODE Pin Configuration). In the hiccup mode, the controller shuts down after detecting cycle-by-cycle current
limiting for 128 consecutive cycles and the soft-start capacitor is discharged. The soft-start capacitor is
automatically released after 4000 oscillator clock cycles and the controller restarts. If hiccup mode protection is
not enabled through the MODE pin, the LM5175 will operate in cycle-by-cycle current limiting as long as the
overload condition persists.
8.3.6 Average Input/Output Current Limiting
The LM5175 provides optional average current limiting capability to limit either the input or the output current of
the DC/DC converter. The average current limiting circuit uses an additional current sense resistor connected in
series with the input supply or output voltage of the converter. A current sense gm amplifier with inputs at the
ISNS(+) and ISNS(-) pins monitors the voltage across the sense resistor and compares it with an internal 50 mV
reference. If the drop across the sense resistor is greater than 50 mV, the gm amplifier gradually discharges the
soft-start capacitor. When the soft-start capacitor discharges below the 0.8-V feedback reference voltage VREF
,
the output voltage of the converter decreases to limit the input or output current. The average current limiting
feature can be used in applications requiring a regulated current from the input supply or into the load. The target
constant current is given by Equation 4:
50 mV
ICL(AVG)
=
RSNS
(4)
The average current loop can be disabled by shorting the ISNS(+) and ISNS(-) pins together.
8.3.7 CCM/DCM Operation
The LM5175 allows selection of continuous conduction mode (CCM) or discontinuous conduction mode (DCM)
operation using the MODE pin (see MODE Pin Configuration). In CCM operation the inductor current can flow in
either direction and the controller switches at a fixed frequency regardless of the load current. This mode is
useful for noise-sensitive applications where a fixed switching eases filter design. In DCM operation the
synchronous rectifier MOSFETs emulate diodes as LDRV1 or HDRV2 turn-off for the remainder of the PWM
cycle when the inductor current reaches zero. The DCM mode results in reduced frequency operation at light
loads, which lowers switching losses and increases light load efficiency of the converter.
8.3.8 Frequency and Synchronization (RT/SYNC)
The LM5175 switching frequency can be programmed between 100 kHz and 600 kHz using a resistor from the
RT/SYNC pin to AGND. The RT resistor is related to the nominal switching frequency (Fsw) by the following
equation:
≈
∆
«
’
÷
1
- 200 ns
F
sw ◊
RT
=
37 pF
(5)
Figure 3 in the Typical Characteristics shows the relationship between the programmed switching frequency (Fsw)
and the RT resistor.
The RT/SYNC pin can also be used for synchronizing the internal oscillator to an external clock signal. The
external synchronization pulse is ac coupled using a capacitor to the RT/SYNC pin. The voltage at the RT/SYNC
pin must not exceed 3.3 V peak. The external synchronization pulse frequency should be higher than the
internally set oscillator frequency and the pulse width should be between 75 ns and 500 ns.
16
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Feature Description (continued)
LM5175
RT/SYNC
external SYNC
CSYNC
RT
Copyright © 2016, Texas Instruments Incorporated
Figure 22. Using External SYNC
8.3.9 Frequency Dithering
The LM5175 provides an optional frequency dithering function that is enabled by connecting a capacitor from
DITH to AGND. Figure 23 illustrates the dithering circuit. A triangular waveform centered at 1.22 V is generated
across the CDITH capacitor. This triangular waveform modulates the oscillator frequency by ±5% of the nominal
frequency set by the RT resistor. The CDITH capacitance value sets the rate of the low frequency modulation. A
lower CDITH capacitance will modulate the oscillator frequency at a faster rate than a higher capacitance. For the
dithering circuit to effectively reduce peak EMI, the modulation rate must be much less than the oscillator
frequency (Fsw). Equation 6 calculates the DITH pin capacitance required to set the modulation frequency, FMOD
.
Connecting the DITH pin directly to AGND disables frequency dithering, and the internal oscillator operates at a
fixed frequency set by the RT resistor. Dither is disabled when external SYNC is used.
10 mA
FMOD ì0.24 V
CDITH
=
(6)
1.22 V + 5%
1.22 V
LM5175
1.22 V - 5 %
DITH
CDITH
Copyright © 2016, Texas Instruments Incorporated
Figure 23. Dither Operation
8.3.10 Output Overvoltage Protection (OVP)
The LM5175 provides an output overvoltage protection (OVP) circuit that turns off the gate drives when the
feedback voltage is 7.5% above the 0.8 V feedback reference voltage VREF. Switching resumes once the output
falls within 5% of VREF
.
8.3.11 Power Good (PGOOD)
PGOOD is an open drain output that is pulled low when the voltage at the FB pin is outside -9% / +10% of the
nominal 0.8-V reference voltage. The PGOOD internal N-Channel MOSFET pull-down strength is typically 4.2
mA. This pin can be connected to a voltage supply of up to 8 V through a pull-up resistor.
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Feature Description (continued)
8.3.12 Gm Error Amplifier
The LM5175 has a gm error amplifier for loop compensation. The gm amplifier output (COMP) range is 0.3 V to
3 V. Connect an Rc1-Cc1 compensation network between COMP and ground for type II (PI) compensation (see
Figure 24). Another pole is usually added using Cc2 to suppress higher frequency noise.
The COMP output voltage (VCOMP) range limits the possible VIN and IOUT range for a given design. In buck mode,
the maximum VIN for which the converter can regulate the output at no load is when VCOMP reaches 0.3 V.
Equation 7 gives VCOMP as a function of VIN at no load in CCM buck mode:
2 mS∂ V - V
+ 6 mA
VOUT
(
)
sw
IN
OUT
VCOMP(BUCK) = 1.6 V - ACS ∂RSENSE
∂
∂ 1-D
(
-
∂ 1-D
(
BUCK
)
)
BUCK
2∂L1∂F
CSLOPE ∂F
sw
(7)
(8)
Where DBUCK in the equation Equation 7 is the buck duty cycle given by:
VOUT
DBUCK
=
V
IN
A larger L1, lower slope ripple (higher CSLOPE), smaller sense resistor (RSENSE), and higher frequency can
increase the maximum VIN range for buck operation.
For boost mode, the minimum VIN for which the converter can regulate the output at full load is when VCOMP
reaches 3 V. Equation 9 gives VCOMP as a function of VIN in boost mode:
2mS∂ V
- V + 5mA
IN
≈
’
÷
◊
VOUT
V
(
)
OUT
IN
VCOMP(BOOST) = 1.6V + ACS ∂RSENSE ∂ I
∂
+
∂DBOOST
+
∂DBOOST
∆
OUT
V
2∂L1∂F
CSLOPE ∂F
sw
«
IN
sw
(9)
Where DBOOST in the Equation 9 is the boost duty cycle given by:
V
IN
DBOOST = 1-
VOUT
(10)
A larger L1, lower slope ripple (higher CSLOPE), smaller sense resistor (RSENSE), and higher frequency can extend
the minimum VIN range for boost operation.
8.3.13 Integrated Gate Drivers
The LM5175 provides four N-channel MOSFET gate drivers: two floating high-side gate drivers at the HDRV1
and HDRV2 pins, and two ground referenced low-side drivers at the LDRV1 and LDRV2 pins. Each driver is
capable of sourcing 1.5 A and sinking 2 A peak current. In buck operation, LDRV1 and HDRV1 are switched by
the PWM controller while HDRV2 remains continuously on. In boost operation, LDRV2 and HDRV2 are switched
while HDRV1 remains continuously on.
In DCM buck operation, LDRV1 and HDRV2 turn off when the inductor current drops to zero (diode emulation).
In a DCM boost operation, HDRV2 turns off when inductor current drops to zero.
The gate drive output HDRV2 remains off during soft-start to prevent reverse current flow from a pre-biased
output.
The low-side gate drivers are powered from VCC and the high-side gate drivers HDRV1 and HDRV2 are
powered from bootstrap capacitors CBOOT1 (between BOOT1 and SW1) and CBOOT2 (between BOOT2 and SW2)
respectively. The CBOOT1 and CBOOT2 capacitors are charged through external Schottky diodes connected to the
VCC pin as shown in Figure 24.
8.3.14 Thermal Shutdown
The LM5175 is protected by a thermal shutdown circuit that shuts down the device when the internal junction
temperature exceeds 165°C (typical). The soft-start capacitor is discharged when thermal shutdown is triggered
and the gate drivers are disabled. The converter automatically restarts when the junction temperature drops by
the thermal shutdown hysteresis of 15°C below the thermal shutdown threshold.
18
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ZHCSDH1A –OCTOBER 2015–REVISED MAY 2016
8.4 Device Functional Modes
Please refer to Enable/UVLO section for the description of EN/UVLO pin function. Shutdown, Standby, and
Operating Modes section lists the shutdown, standby, and operating modes for LM5175 as a function of
EN/UVLO and VCC voltages.
8.4.1 Shutdown, Standby, and Operating Modes
EN/UVLO
VCC
DEVICE MODE
EN/UVLO < 0.7 V
0.7 V < EN/UVLO < 1.23 V
EN/UVLO > 1.23 V
EN/UVLO > 1.23 V
—
Shutdown: VCC off, No switching
Standby: VCC on, No switching
Standby: VCC on, No switching
Operating: VCC on, Switching enabled
—
VCC < 3.3 V
VCC > 3.3 V
8.4.2 MODE Pin Configuration
The MODE pin is used to select CCM/DCM operation and hiccup mode current limit. Mode is latched at startup.
MODE PIN CONNECTION
Connect to VCC
LIGHT LOAD MODE
HICCUP FAULT PROTECTION
No Hiccup
CCM
CCM
DCM
DCM
RMODE to AGND = 93.1 kΩ
RMODE to AGND = 49.9 kΩ
Connect to AGND
Hiccup Enabled
Hiccup Enabled
No Hiccup
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9 Application and Implementation
NOTE
Information in the following applications sections is not part of the TI component
specification, and TI does not warrant its accuracy or completeness. TI’s customers are
responsible for determining suitability of components for their purposes. Customers should
validate and test their design implementation to confirm system functionality.
9.1 Application Information
The LM5175 is a four-switch buck-boost controller. A quick-start tool on the LM5175 product webpage can be
used to design a buck-boost converter using the LM5175. Alternatively, Webench®software can create a
complete buck-boost design using the LM5175 and generate bill of materials, estimate efficiency, solution size,
and cost of the complete solution. The following sections describe a detailed step-by-step design procedure for a
typical application circuit.
9.2 Typical Application
A typical application example is a buck-boost converter operating from a wide input voltage range of 6 V to 36 V
and providing a stable 12 V output voltage with current capability of 6 A.
RSNS
0 Ω
VIN
VOUT
0.1 µF
CVIN
CIN
CIN
4.7 µF
x5
COUT
10 µF
x5
COUT
180 µF
x2
RUV2
249 kΩ
68 µF
10 Ω
100 Ω
1 µF
100 Ω
RUV1
59.0 kΩ
QH1
QH2
QL2
EN/UVLO VINSNS
VIN
ISNS(-) ISNS(+)
HDRV1
BOOT1
L1
4.7 µH
QL1
10 kΩ
VCC
VCC
PGOOD
CBOOT1
0.1 µF
RMODE
SW1
MODE
93.1 kΩ
LDRV1
100 Ω
RT/SYNC
CS
CSYNC
1 nF
RSENSE
8 mΩ
47 pF
RT
CSG
84.5 kΩ
LM5175
100 Ω
SS
CSS
0.1 µF
LDRV2
BOOT2
VOUT
BIAS
VCC
CBIAS
CBOOT2
0.1 µF
0.1 µF
SW2
AGND
PGND
HDRV2
VOSNS
VCC
DITH
COMP
SLOPE
FB
CVCC
1 µF
CSLOPE
100 pF
Cc1
22 nF
RRB2
RRB1
20 kΩ
280 kΩ
Cc2
Rc1
10 kΩ
100 pF
Copyright © 2016, Texas Instruments Incorporated
Figure 24. LM5175 Four-Switch Buck Boost Application Schematic
20
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LM5175
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ZHCSDH1A –OCTOBER 2015–REVISED MAY 2016
Typical Application (continued)
9.2.1 Design Requirements
For this design example, the following are used as the input parameters.
DESIGN PARAMETER
Input Voltage Range
Output
EXAMPLE VALUE
6 V to 36 V
12 V
Load Current
6 A
Switching Frequency
Mode
300 kHz
CCM, Hiccup
9.2.2 Detailed Design Procedure
9.2.2.1 Frequency
The switching frequency of LM5175 is set by an RT resistor connected from RT/SYNC pin to AGND. The RT
resistor required to set the desired frequency is calculated using Equation 5 or Figure 3 . A 1% standard resistor
of 84.5 kΩ is selected for Fsw = 300 kHz.
9.2.2.2 VOUT
The output voltage is set using a resistor divider to the FB pin. The internal reference voltage is 0.8 V. Normally
the bottom resistor in the resistor divider is selected to be in the 1 kΩ to 100 kΩ range. Select
RFB1 = 20 kW
(11)
The top resistor in the feedback resistor divider is selected using Equation 12:
VOUT - 0.8 V
RFB2
=
ìRFB1 = 280 kW
0.8 V
(12)
9.2.2.3 Inductor Selection
The inductor selection is based on consideration of both buck and boost modes of operation. For the buck mode,
inductor selection is based on limiting the peak to peak current ripple ΔIL to ~40% of the maximum inductor
current at the maximum input voltage. The target inductance for the buck mode is:
(V
- VOUT )ì VOUT
IN(MAX)
LBUCK
=
= 11.1mH
0.4ìIOUT(MAX) ìF ì V
sw
IN(MAX)
(13)
For the boost mode, the inductor selection is based on limiting the peak to peak current ripple ΔIL to ~40% of the
maximum inductor current at the minimum input voltage. The target inductance for the boost mode is:
VI2N(MIN) ì(VOUT - V
)
IN(MIN)
LBOOST
=
= 2.1mH
0.4ìIOUT(MAX) ìF ì VO2UT
sw
(14)
In this particular application, the buck inductance is larger. Choosing a larger inductance reduces the ripple
current but also increases the size of the inductor. A larger inductor also reduces the achievable bandwidth of the
converter by moving the right half plane zero to lower frequencies. Therefore a judicious compromise should be
made based on the application requirements. For this design a 4.7-µH inductor is selected. With this inductor
selection, the inductor current ripple is 5.7 A, 4.3 A, and 2.1 A, at VIN of 36 V, 24 V, and 6 V respectively.
The maximum average inductor current occurs at the minimum input voltage and maximum load current:
VOUT ìIOUT(MAX)
IL(MAX)
=
= 13.3 A
0.9ì V
IN(MIN)
(15)
where a 90% efficiency is assumed. The peak inductor current occurs at minimum input voltage and is given by:
IN(MIN) ì(VOUT - V
V
)
IN(MIN)
IL(PEAK) = IL(MAX)
+
= 14.4 A
2ìL1ìF ì VOUT
sw
(16)
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LM5175
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www.ti.com.cn
To ensure sufficient output current, the current limit threshold must be set to allow the maximum load current in
boost operation. To ensure that the inductor does not saturate in current limit, the peak saturation current of the
inductor should be higher than the maximum current limit. Adjusting for a ±20% current limit threshold tolerance,
the peak inductor current limit is:
1.2ìIL(PEAK)
IL(SAT)
=
= 21.6 A
0.8
(17)
Therefore, the inductor saturation current should be greater than 21.6 A. If hiccup mode protection is not
enabled, the RMS current rating of the inductor should be sufficient to tolerate continuous operation in cycle-by-
cycle current limiting.
9.2.2.4 Output Capacitor
In the boost mode, the output capacitor conducts high ripple current. The output capacitor RMS ripple current is
given by Equation 18 where the minimum VIN corresponds to the maximum capacitor current.
VOUT
ICOUT(RMS) = IOUT
ì
-1
V
IN
(18)
In this example the maximum output ripple RMS current is ICOUT(RMS) = 6 A. A 5-mΩ output capacitor ESR
causes an output ripple voltage of 60 mV as given by:
IOUT ì VOUT
DVRIPPLE(ESR)
=
ìESR
V
IN(MIN)
(19)
A 400 µF output capacitor causes a capacitive ripple voltage of 25 mV as given by:
V
≈
’
÷
◊
IN(MIN)
IOUT ì 1-
∆
VOUT
«
DVRIPPLE(COUT)
=
COUT ìF
sw
(20)
Typically a combination of ceramic and bulk capacitors is needed to provide low ESR and high ripple current
capacity. The complete schematic in Figure 24 at the end of this section shows a good starting point for COUT for
typical applications.
9.2.2.5 Input Capacitor
In the buck mode, the input capacitor supplies high ripple current. The RMS current in the input capacitor is given
by:
ICIN(RMS) = IOUT Dì(1-D)
(21)
The maximum RMS current occurs at D = 0.5, which gives ICIN(RMS) = IOUT/2 = 3 A. A combination of ceramic and
bulk capacitors should be used to provide short path for high di/dt current and to reduce the output voltage ripple.
The complete schematic in Figure 24 is a good starting point for CIN for typical applications.
9.2.2.6 Sense Resistor (RSENSE
)
The current sense resistor between the CS and CSG pins should be selected to ensure that current limit is set
high enough for both buck and boost modes of operation. For the buck operation, the current limit resistor is
given by:
76 mV ì70%
IOUT(MAX)
RSENSE(BUCK)
=
= 8.8 mW
(22)
For the boost mode of operation, the current limit resistor is given by:
170 mV ì70%
RSENSE(BOOST)
=
= 8.2 mW
IL(PEAK)
(23)
The closest standard value of RSENSE = 8 mΩ is selected based on the boost mode operation.
22
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The maximum power dissipation in RSENSE happens at VIN(MIN)
:
2
V
≈
’
≈
∆
«
’
÷
170mV
IN(MIN)
PRSENSE(MAX)
=
∂RSENSE ∂ 1-
= 1.8W
∆
÷
÷
∆
RSENSE ◊
VOUT
«
◊
(24)
Based on this, select the current sense resistor with power rating of 2 W or higher.
For some application circuits, it may be required to add a filter network to attenuate noise in the CS and CSG
sense lines. Please see Figure 24 for typical values. The filter resistance should not exceed 100 Ω.
9.2.2.7 Slope Compensation
For stable current loop operation and to avoid sub-harmonic oscillations, the slope capacitor should be selected
based on Equation 25:
L1
4.7 mH
8 mWì5
CSLOPE = gmSLOPE
ì
= 2 mSì
= 235 pF
RSENSE ì ACS
(25)
This slope compensation results in “dead-beat” operation, in which the current loop disturbances die out in one
switching cycle. Theoretically a current mode loop is stable with half the “dead-beat” slope (twice the calculated
slope capacitor value in Equation 25). A smaller slope capacitor results in larger slope signal which is better for
noise immunity in the transition region (VIN~VOUT). A larger slope signal, however, restricts the achievable input
voltage range for a given output voltage, switching frequency, and inductor. For this design CSLOPE = 100 pF is
selected for better transition region behavior while still providing the required VIN range. This selection of slope
capacitor, inductor, switching frequency, and inductor satisfies the COMP range limitation explained in Gm Error
Amplifier section.
9.2.2.8 UVLO
The UVLO resistor divider must be designed for turn-on below 6V. Selecting a RUV2 = 249 kΩ gives a UVLO
hysteresis of 0.8 V. The lower UVLO resistor is the selected using Equation 26:
RUV2 ì1.23 V
+1.5 mA ìRUV2 -1.23 V
RUV1
=
= 59.5 kW
V
IN
UV
(
)
(26)
A standard value of 59.0 kΩ is selected for RUV1
.
When programming the UVLO threshold for lower input voltage operation, it is important to choose MOSFETs
with gate (Miller) plateau voltage lower than the minimum VIN.
9.2.2.9 Soft-Start Capacitor
The soft-start time is programmed using the soft-start capacitor. The relationship between CSS and the soft-start
time is given by:
0.8 V ìCSS
tss
=
5 mA
(27)
CSS = 0.1 µF gives a soft-start time of 16 ms.
9.2.2.10 Dither Capacitor
The dither capacitor sets the modulation frequency of the frequency dithering around the nominal switching
frequency. A larger CDITH results in lower modulation frequency. For proper operation the modulation frequency
(FMOD) must be much lower than the switching frequency. Use Equation 28 to select CDITH for the target
modulation frequency.
10 mA
FMOD ì0.24 V
CDITH
=
(28)
For the current design dithering is not being implemented. Therefore a 0 Ω resistor from the DITH pin to AGND
disables this feature.
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9.2.2.11 MOSFETs QH1 and QL1
The input side MOSFETs QH1 and QL1 need to withstand the maximum input voltage of 36 V. In addition they
must withstand the transient spikes at SW1 during switching. Therefore QH1 and QL1 should be rated for 60 V.
The gate plateau voltages of the MOSFETs should be smaller than the minimum input voltage of the converter,
otherwise the MOSFETs may not fully enhance during startup or overload conditions.
The power loss in QH1 in the boost mode of operation is approximated by:
2
≈
’
÷
VOUT
V
PCOND(QH1) = I
∂
∂RDSON(QH1)
∆
OUT
«
IN ◊
(29)
The power loss in QH1 in the buck mode of operation consists of both conduction and switching loss
components given by Equation 30 and Equation 31 respectively:
≈
∆
«
’
÷
VOUT
V
PCOND(QH1)
=
∂I
2 ∂RDSON(QH1)
OUT
IN ◊
(30)
(31)
1
2
PSW(QH1)
=
∂ VIN ∂IOUT ∂ t + t ∂F
r f sw
(
)
The rise (tr) and the fall (tf) times are based on the MOSFET datasheet information or measured in the lab.
Typically a MOSFET with smaller RDSON (smaller conduction loss) will have longer rise and fall times (larger
switching loss).
The power loss in QL1 in the buck mode of operation is given by the following equation:
≈
’
÷
VOUT
V
PCOND(QL1) = 1-
∂I
2 ∂RDSON(QL1)
OUT
∆
«
IN ◊
(32)
9.2.2.12 MOSFETs QH2 and QL2
The output side MOSFETs QH2 and QL2 see the output voltage of 12 V and additional transient spikes at SW2
during switching. Therefore QH2 and QL2 should be rated for 20 V or more. The gate plateau voltages of the
MOSFETs should be smaller than the minimum input voltage of the converter, otherwise the MOSFETs may not
fully enhance during startup or overload conditions.
The power loss in QH2 in the buck mode of operation is approximated by:
PCOND(QH2) = IOUT2 ∂RDSON(QH2)
(33)
The power loss in QL2 in the boost mode of operation consists of both conduction and switching loss
components given by Equation 34 and Equation 35 respectively:
2
≈
’ ≈
’
÷
V
VOUT
IN
PCOND(QL2) = 1-
∂ I
÷ ∆ OUT
∂
∂RDSON(QL2)
∆
VOUT ◊ «
V
«
IN ◊
(34)
(35)
≈
’
÷
VOUT
V
1
PSW(QL2)
=
∂ VOUT ∂ I
∂
∂ t + t ∂F
r f sw
(
)
∆
«
OUT
2
IN ◊
The rise (tr) and the fall (tf) times can be based on the MOSFET datasheet information or measured in the lab.
Typically a MOSFET with smaller RDSON (lower conduction loss) has longer rise and fall times (larger switching
loss).
The power loss in QH2 in the boost mode of operation is given by the following equation:
2
≈
’
÷
V
VOUT
IN
PCOND(QH2)
=
∂ I
∂
∂RDSON(QH2)
∆
OUT
VOUT «
V
IN ◊
(36)
24
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ZHCSDH1A –OCTOBER 2015–REVISED MAY 2016
9.2.2.13 Frequency Compensation
This section presents the control loop compensation design procedure for the LM5175 buck-boost controller. The
LM5175 operates mainly in buck or boost modes, separated by a transition region, and therefore the control loop
design is done for both buck and boost operating modes. Then a final selection of compensation is made based
on the mode that is more restrictive from a loop stability point of view. Typically for a converter designed to go
deep into both buck and boost operating regions, the boost compensation design is more restrictive due to the
presence of a right half plane zero (RHPZ) in the boost mode.
The boost power stage output pole location is given by:
≈
∆
’
÷
1
2
ƒp1(boost)
=
= 398 Hz
2p ROUT ìCOUT ◊
«
(37)
where ROUT = 2 Ω corresponds to the maximum load of 6 A.
The boost power stage ESR zero location is given by:
≈
∆
’
÷
1
1
ƒz1
=
= 79.6 kHz
2p RESR ìCOUT ◊
«
(38)
(39)
The boost power stage RHP zero location is given by:
2
≈
’
ROUT ì(1-DMAX
)
1
ƒRHP
=
= 16.9 kHz
∆
∆
«
÷
÷
◊
2p
L1
where DMAX is the maximum duty cycle at the minimum VIN.
The buck power stage output pole location is given by:
≈
∆
’
÷
1
1
ƒp1(buck)
=
= 199 Hz
2p ROUT ìCOUT ◊
«
(40)
The buck power stage ESR zero location is the same as the boost power stage ESR zero.
It is clear from Equation 39 that RHP zero is the main factor limiting the achievable bandwidth. For a robust
design the crossover frequency should be less than 1/3 of the RHP zero frequency. Given the position of the
RHP zero, a reasonable target bandwidth in boost operation is around 4 kHz:
ƒbw = 4 kHz
(41)
For some power stages, the boost RHP zero might not be as restrictive. This happens when the boost maximum
duty cycle (DMAX) is small, or when a really small inductor is used. In those cases, compare the limits posed by
the RHP zero (fRHP/3) with 1/20 of the switching frequency and use the smaller of the two values as the
achievable bandwidth.
The compensation zero can be placed at 1.5 times the boost output pole frequency. Keep in mind that this
locates the zero at 3 times the buck output pole frequency which results in approximately 30 degrees of phase
loss before crossover of the buck loop and 15 degrees of phase loss at intermediate frequencies for the boost
loop:
ƒzc = 600 Hz
(42)
If the crossover frequency is well below the RHP zero and the compensation zero is placed well below the
crossover, the compensation gain resistor Rc1 is calculated using the approximation:
2pì ƒbw RFB1 +RFB2 ACS ìRSENSE ìCOUT
Rc1
=
ì
ì
= 9.49 kW
gmEA
RFB1
1-DMAX
(43)
where DMAX is the maximum duty cycle at the minimum VIN in boost mode and ACS is the current sense amplifier
gain. The compensation capacitor Cc1 is then calculated from:
1
Cc1
=
= 27.9 nF
2ì pì ƒzc ìRc1
(44)
The standard values of compensation components are selected to be Rc1 = 10 kΩ and Cc1 = 22 nF.
Copyright © 2015–2016, Texas Instruments Incorporated
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LM5175
ZHCSDH1A –OCTOBER 2015–REVISED MAY 2016
www.ti.com.cn
A high frequency pole is added to suppress switching noise using a 100 pF capacitor (Cc2) in parallel with Rc1
and Cc1. These values provide a good starting point for the compensation design. Each design should be tuned
in the lab to achieve the desired balance between stability margin across the operating range and transient
response time.
9.2.3 Application Curves
100
95
90
85
VIN=6V
VIN=12V
VIN=24V
80
0
1
2
3
4
5
6
LOAD CURRENT (A)
Figure 26. Output Voltage Ripple
D008
Figure 25. Efficiency vs Load
Figure 27. Load Transient Response
Figure 28. Line Transient Response (8 V - 24 V, IOUT = 2 A)
26
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LM5175
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ZHCSDH1A –OCTOBER 2015–REVISED MAY 2016
10 Power Supply Recommendations
The LM5175 is a power management device. The power supply for the device is any dc voltage source within the
specified input range. The supply should also be capable of supplying sufficient current based on the maximum
inductor current in boost mode operation. The input supply should be bypassed with additional electrolytic
capacitor at the input of the application board to avoid ringing due to parasitic impedance of the connecting
cables.
11 Layout
11.1 Layout Guidelines
The basic PCB board layout requires separation of sensitive signal and power paths. The following checklist
should be followed to get good performance for a well designed board.
•
•
•
Place the power components including the input filter capacitor CIN, the power MOSFETs QL1 and QH1, and
the sense resistor RSENSE close together to minimize the loop area for input switching current in buck
operation.
Place the power components including the output filter capacitor COUT, the power MOSFETs QL2 and QH2,
and the sense resistor RSENSE close together to minimize the loop area for output switching current in boost
operation.
Use a combination of bulk capacitors and smaller ceramic capacitors with low series impedance for the input
and output capacitors. Place the smaller capacitors closer to the IC to provide a low impedance path for high
di/dt switching currents.
•
•
Minimize the SW1 and SW2 loop areas as these are high dv/dt nodes.
Layout the gate drive traces and return paths as directly as possible. Layout the forward and return traces
close together, either running side by side or on top of each other on adjacent layers to minimize the
inductance of the gate drive path.
•
Use Kelvin connections to RSENSE for the current sense signals CS and CSG and run lines in parallel from the
RSENSE terminals to the IC pins. Avoid crossing noisy areas such as SW1 and SW2 nodes or high-side gate
drive traces. Place the filter capacitor for the current sense signal as close to the IC pins as possible.
•
•
•
Place the CIN, COUT, and RSENSE ground pins as close as possible with thick ground trace and/or planes on
multiple layers.
Place the VCC bypass capacitor close to the controller IC, between the VCC and PGND pins. A 1-µF ceramic
capacitor is typically used.
Place the BIAS bypass capacitor close to the controller IC, between the BIAS and PGND pins. A 0.1-µF
ceramic capacitor is typically used.
•
•
•
Place the BOOT1 bootstrap capacitor close to the IC and connect directly to the BOOT1 to SW1 pins.
Place the BOOT2 bootstrap capacitor close to the IC and connect directly to the BOOT2 to SW2 pins.
Bypass the VIN pin to AGND with a low ESR ceramic capacitor located close to the controller IC. A 0.1 µF
ceramic capacitor is typically used. When using external BIAS, use a diode between input rails and VIN pins to
prevent reverse conduction when VIN < VCC.
•
•
Connect the feedback resistor divider between the COUT positive terminal and AGND pin of the IC. Place the
components close to the FB pin.
Use care to separate the power and signal paths so that no power or switching current flows through the
AGND connections which can either corrupt the COMP, SLOPE, or SYNC signals, or cause dc offset in the
FB sense signal. The PGND and AGND traces can be connected near the PGND pin, near the VCC
capacitor PGND connection, or near the PGND connection of the CS, CSG pin current sense resistor.
•
When using the average current loop, divide the overall capacitor (CIN or COUT) between the two sides of the
sense resistor to ensure small cycle-by-cycle ripple. Place the average current loop filter capacitor close to
the IC between the ISNS(+) and ISNS(-) pins.
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LM5175
ZHCSDH1A –OCTOBER 2015–REVISED MAY 2016
www.ti.com.cn
11.2 Layout Example
L1
SW1
SW2
VOUT
VIN
QL1
QL2
QH1
QH2
RISNS
COUT
CIN
CIN
RSENSE
COUT
LM5175
GND
GND
Figure 29. LM5175 Power Stage Layout
28
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LM5175
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ZHCSDH1A –OCTOBER 2015–REVISED MAY 2016
12 器件和文档支持
12.1 文档支持
12.1.1 相关文档ꢀ
请访问德州仪器 (TI) 主页以获取最新技术文档,包括应用笔记、用户指南和参考设计。
应用报告《IC 封装热指标》,SPRA953.
12.2 社区资源
The following links connect to TI community resources. Linked contents are provided "AS IS" by the respective
contributors. They do not constitute TI specifications and do not necessarily reflect TI's views; see TI's Terms of
Use.
TI E2E™ Online Community TI's Engineer-to-Engineer (E2E) Community. Created to foster collaboration
among engineers. At e2e.ti.com, you can ask questions, share knowledge, explore ideas and help
solve problems with fellow engineers.
Design Support TI's Design Support Quickly find helpful E2E forums along with design support tools and
contact information for technical support.
12.3 商标
PowerPAD, E2E are trademarks of Texas Instruments.
Webench is a registered trademark of Texas Instruments.
All other trademarks are the property of their respective owners.
12.4 静电放电警告
这些装置包含有限的内置 ESD 保护。 存储或装卸时,应将导线一起截短或将装置放置于导电泡棉中,以防止 MOS 门极遭受静电损
伤。
12.5 Glossary
SLYZ022 — TI Glossary.
This glossary lists and explains terms, acronyms, and definitions.
13 机械、封装和可订购信息
以下页中包括机械、封装和可订购信息。这些信息是针对指定器件可提供的最新数据。这些数据会在无通知且不对
本文档进行修订的情况下发生改变。欲获得该数据表的浏览器版本,请查阅左侧的导航栏
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PACKAGE OPTION ADDENDUM
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PACKAGING INFORMATION
Orderable Device
Status Package Type Package Pins Package
Eco Plan
Lead finish/
Ball material
MSL Peak Temp
Op Temp (°C)
Device Marking
Samples
Drawing
Qty
(1)
(2)
(3)
(4/5)
(6)
LM5175PWPR
LM5175PWPT
LM5175RHFR
LM5175RHFT
ACTIVE
ACTIVE
ACTIVE
ACTIVE
HTSSOP
HTSSOP
VQFN
PWP
PWP
RHF
RHF
28
28
28
28
2000 RoHS & Green
250 RoHS & Green
3000 RoHS & Green
250 RoHS & Green
NIPDAU
Level-3-260C-168 HR
Level-3-260C-168 HR
Level-2-260C-1 YEAR
Level-2-260C-1 YEAR
-40 to 125
-40 to 125
-40 to 125
-40 to 125
LM5175
NIPDAU
NIPDAU
NIPDAU
LM5175
LM5175
LM5175
VQFN
(1) The marketing status values are defined as follows:
ACTIVE: Product device recommended for new designs.
LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect.
NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design.
PREVIEW: Device has been announced but is not in production. Samples may or may not be available.
OBSOLETE: TI has discontinued the production of the device.
(2) RoHS: TI defines "RoHS" to mean semiconductor products that are compliant with the current EU RoHS requirements for all 10 RoHS substances, including the requirement that RoHS substance
do not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, "RoHS" products are suitable for use in specified lead-free processes. TI may
reference these types of products as "Pb-Free".
RoHS Exempt: TI defines "RoHS Exempt" to mean products that contain lead but are compliant with EU RoHS pursuant to a specific EU RoHS exemption.
Green: TI defines "Green" to mean the content of Chlorine (Cl) and Bromine (Br) based flame retardants meet JS709B low halogen requirements of <=1000ppm threshold. Antimony trioxide based
flame retardants must also meet the <=1000ppm threshold requirement.
(3) MSL, Peak Temp. - The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature.
(4) There may be additional marking, which relates to the logo, the lot trace code information, or the environmental category on the device.
(5) Multiple Device Markings will be inside parentheses. Only one Device Marking contained in parentheses and separated by a "~" will appear on a device. If a line is indented then it is a continuation
of the previous line and the two combined represent the entire Device Marking for that device.
(6)
Lead finish/Ball material - Orderable Devices may have multiple material finish options. Finish options are separated by a vertical ruled line. Lead finish/Ball material values may wrap to two
lines if the finish value exceeds the maximum column width.
Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided. TI bases its knowledge and belief on information
provided by third parties, and makes no representation or warranty as to the accuracy of such information. Efforts are underway to better integrate information from third parties. TI has taken and
Addendum-Page 1
PACKAGE OPTION ADDENDUM
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10-Dec-2020
continues to take reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on incoming materials and chemicals.
TI and TI suppliers consider certain information to be proprietary, and thus CAS numbers and other limited information may not be available for release.
In no event shall TI's liability arising out of such information exceed the total purchase price of the TI part(s) at issue in this document sold by TI to Customer on an annual basis.
Addendum-Page 2
PACKAGE MATERIALS INFORMATION
www.ti.com
20-Apr-2023
TAPE AND REEL INFORMATION
REEL DIMENSIONS
TAPE DIMENSIONS
K0
P1
W
B0
Reel
Diameter
Cavity
A0
A0 Dimension designed to accommodate the component width
B0 Dimension designed to accommodate the component length
K0 Dimension designed to accommodate the component thickness
Overall width of the carrier tape
W
P1 Pitch between successive cavity centers
Reel Width (W1)
QUADRANT ASSIGNMENTS FOR PIN 1 ORIENTATION IN TAPE
Sprocket Holes
Q1 Q2
Q3 Q4
Q1 Q2
Q3 Q4
User Direction of Feed
Pocket Quadrants
*All dimensions are nominal
Device
Package Package Pins
Type Drawing
SPQ
Reel
Reel
A0
B0
K0
P1
W
Pin1
Diameter Width (mm) (mm) (mm) (mm) (mm) Quadrant
(mm) W1 (mm)
LM5175PWPR
LM5175RHFR
LM5175RHFT
HTSSOP PWP
28
28
28
2000
3000
250
330.0
330.0
180.0
16.4
12.4
12.4
6.9
4.3
4.3
10.2
5.3
1.8
1.3
1.3
12.0
8.0
16.0
12.0
12.0
Q1
Q1
Q1
VQFN
VQFN
RHF
RHF
5.3
8.0
Pack Materials-Page 1
PACKAGE MATERIALS INFORMATION
www.ti.com
20-Apr-2023
TAPE AND REEL BOX DIMENSIONS
Width (mm)
H
W
L
*All dimensions are nominal
Device
Package Type Package Drawing Pins
SPQ
Length (mm) Width (mm) Height (mm)
LM5175PWPR
LM5175RHFR
LM5175RHFT
HTSSOP
VQFN
PWP
RHF
RHF
28
28
28
2000
3000
250
350.0
346.0
210.0
350.0
346.0
185.0
43.0
33.0
35.0
VQFN
Pack Materials-Page 2
PACKAGE OUTLINE
RHF0028A
VQFN - 1.0 mm max height
S
C
A
L
E
3
.
0
0
0
PLASTIC QUAD FLATPACK - NO LEAD
4.1
3.9
B
A
PIN 1 INDEX AREA
0.5
0.3
5.1
4.9
0.30
0.18
DETAIL
OPTIONAL TERMINAL
TYPICAL
C
1 MAX
SEATING PLANE
0.08 C
0.05
0.00
2.55 0.1
2X 2.5
(0.2) TYP
9
EXPOSED
14
THERMAL PAD
24X 0.5
15
8
3.55 0.1
2X
29
SYMM
3.5
SEE TERMINAL
DETAIL
1
22
0.30
0.18
28X
0.1
C A B
PIN 1 ID
(OPTIONAL)
28
23
SYMM
0.05
0.5
0.3
28X
4220383/A 11/2016
NOTES:
1. All linear dimensions are in millimeters. Any dimensions in parenthesis are for reference only. Dimensioning and tolerancing
per ASME Y14.5M.
2. This drawing is subject to change without notice.
3. The package thermal pad must be soldered to the printed circuit board for thermal and mechanical performance.
www.ti.com
EXAMPLE BOARD LAYOUT
RHF0028A
VQFN - 1.0 mm max height
PLASTIC QUAD FLATPACK - NO LEAD
(2.55)
SYMM
28
23
28X (0.6)
22
1
28X (0.24)
(3.55)
(1.525)
24X (0.5)
29
SYMM
(4.8)
(
0.2) TYP
VIA
8
15
(R0.05)
TYP
9
14
(1.025)
(3.8)
LAND PATTERN EXAMPLE
SCALE:18X
0.07 MIN
ALL AROUND
0.07 MAX
ALL AROUND
SOLDER MASK
OPENING
METAL
SOLDER MASK
OPENING
METAL UNDER
SOLDER MASK
NON SOLDER MASK
DEFINED
SOLDER MASK
DEFINED
(PREFERRED)
SOLDER MASK DETAILS
4220383/A 11/2016
NOTES: (continued)
4. This package is designed to be soldered to a thermal pad on the board. For more information, see Texas Instruments literature
number SLUA271 (www.ti.com/lit/slua271).
5. Vias are optional depending on application, refer to device data sheet. If any vias are implemented, refer to their locations shown
on this view. It is recommended that vias under paste be filled, plugged or tented.
www.ti.com
EXAMPLE STENCIL DESIGN
RHF0028A
VQFN - 1.0 mm max height
PLASTIC QUAD FLATPACK - NO LEAD
4X (1.13)
(0.665) TYP
23
28
28X (0.6)
1
22
28X (0.24)
(0.865)
TYP
24X (0.5)
SYMM
(4.8)
29
4X (1.53)
(R0.05) TYP
8
15
METAL
TYP
14
9
SYMM
(3.8)
SOLDER PASTE EXAMPLE
BASED ON 0.125 mm THICK STENCIL
EXPOSED PAD 29
76% PRINTED SOLDER COVERAGE BY AREA UNDER PACKAGE
SCALE:20X
4220383/A 11/2016
NOTES: (continued)
6. Laser cutting apertures with trapezoidal walls and rounded corners may offer better paste release. IPC-7525 may have alternate
design recommendations.
www.ti.com
PACKAGE OUTLINE
PWP0028C
PowerPADTM TSSOP - 1.2 mm max height
S
C
A
L
E
2
.
0
0
0
SMALL OUTLINE PACKAGE
C
6.6
6.2
TYP
A
0.1 C
PIN 1 INDEX
AREA
SEATING
PLANE
26X 0.65
28
1
2X
9.8
9.6
8.45
NOTE 3
14
15
0.30
0.19
28X
4.5
4.3
B
0.1
C A B
SEE DETAIL A
(0.15) TYP
2X 0.95 MAX
NOTE 5
14
15
2X 0.2 MAX
NOTE 5
0.25
GAGE PLANE
1.2 MAX
5.18
4.48
THERMAL
PAD
0.15
0.05
0.75
0.50
0 -8
A
20
DETAIL A
TYPICAL
1
28
3.1
2.4
4223582/A 03/2017
PowerPAD is a trademark of Texas Instruments.
NOTES:
1. All linear dimensions are in millimeters. Any dimensions in parenthesis are for reference only. Dimensioning and tolerancing
per ASME Y14.5M.
2. This drawing is subject to change without notice.
3. This dimension does not include mold flash, protrusions, or gate burrs. Mold flash, protrusions, or gate burrs shall not
exceed 0.15 mm per side.
4. Reference JEDEC registration MO-153.
5. Features may differ or may not be present.
www.ti.com
EXAMPLE BOARD LAYOUT
PWP0028C
PowerPADTM TSSOP - 1.2 mm max height
SMALL OUTLINE PACKAGE
(3.4)
NOTE 9
(3.1)
METAL COVERED
BY SOLDER MASK
SYMM
28X (1.5)
1
28X (0.45)
28
SEE DETAILS
(R0.05) TYP
(5.18)
(0.6)
26X (0.65)
SYMM
(9.7)
NOTE 9
SOLDER MASK
DEFINED PAD
(1.2) TYP
(
0.2) TYP
VIA
14
15
(1.2) TYP
(5.8)
LAND PATTERN EXAMPLE
EXPOSED METAL SHOWN
SCALE: 8X
SOLDER MASK
OPENING
METAL UNDER
SOLDER MASK
SOLDER MASK
OPENING
METAL
EXPOSED METAL
EXPOSED METAL
0.05 MAX
ALL AROUND
0.05 MIN
ALL AROUND
NON-SOLDER MASK
DEFINED
SOLDER MASK
DEFINED
15.000
(PREFERRED)
SOLDER MASK DETAILS
4223582/A 03/2017
NOTES: (continued)
6. Publication IPC-7351 may have alternate designs.
7. Solder mask tolerances between and around signal pads can vary based on board fabrication site.
8. This package is designed to be soldered to a thermal pad on the board. For more information, see Texas Instruments literature
numbers SLMA002 (www.ti.com/lit/slma002) and SLMA004 (www.ti.com/lit/slma004).
9. Size of metal pad may vary due to creepage requirement.
10. Vias are optional depending on application, refer to device data sheet. It is recommended that vias under paste be filled, plugged
or tented.
www.ti.com
EXAMPLE STENCIL DESIGN
PWP0028C
PowerPADTM TSSOP - 1.2 mm max height
SMALL OUTLINE PACKAGE
(3.1)
BASED ON
0.125 THICK
STENCIL
28X (1.5)
METAL COVERED
BY SOLDER MASK
1
28X (0.45)
28
(R0.05) TYP
26X (0.65)
SYMM
(5.18)
BASED ON
0.125 THICK
STENCIL
15
14
SYMM
(5.8)
SEE TABLE FOR
DIFFERENT OPENINGS
FOR OTHER STENCIL
THICKNESSES
SOLDER PASTE EXAMPLE
BASED ON 0.125 mm THICK STENCIL
SCALE: 8X
STENCIL
THICKNESS
SOLDER STENCIL
OPENING
0.1
3.47 X 5.79
3.10 X 5.18 (SHOWN)
2.83 X 4.73
0.125
0.15
0.175
2.62 X 4.38
4223582/A 03/2017
NOTES: (continued)
11. Laser cutting apertures with trapezoidal walls and rounded corners may offer better paste release. IPC-7525 may have alternate
design recommendations.
12. Board assembly site may have different recommendations for stencil design.
www.ti.com
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