LTC4080XEMSE#TRPBF [Linear]
LTC4080X - 500mA Standalone Li-Ion Charger with Integrated 300mA Synchronous Buck; Package: MSOP; Pins: 10; Temperature Range: -40°C to 85°C;型号: | LTC4080XEMSE#TRPBF |
厂家: | Linear |
描述: | LTC4080X - 500mA Standalone Li-Ion Charger with Integrated 300mA Synchronous Buck; Package: MSOP; Pins: 10; Temperature Range: -40°C to 85°C 光电二极管 |
文件: | 总22页 (文件大小:1077K) |
中文: | 中文翻译 | 下载: | 下载PDF数据表文档文件 |
LTC4080X
500mA Standalone Li-Ion
Charger with Integrated 300mA
Synchronous Buck in 3mm × 3mm DFN
DescripTion
FeaTures
The LTC®4080X is a complete constant-current/constant-
voltage linear battery charger for a single-cell 4.2V
lithium-ion/polymer battery with an integrated 300mA
synchronousbuckconverter.A3mm× 3mmDFNpackage
and low external component count make the LTC4080X
especially suitable for portable applications. Furthermore,
the LTC4080X is specifically designed to work within USB
power specifications.
n
Complete Linear Battery Charger with Integrated
Buck Converter in 3mm x 3mm DFN Package
Battery Charger:
n
Constant-Current/Constant-Voltage Operation
with Thermal Feedback to Maximize Charge Rate
Without Risk of Overheating
Internal 4.5 Hour Safety Timer for Termination
Charge Current Programmable Up to 500mA with
n
n
5% Accuracy
The CHRG pin indicates when charge current has
dropped to ten percent of its programmed value (C/10).
An internal 4.5 hour timer terminates the charge cycle.
The full-featured LTC4080X battery charger also includes
automatic recharge and soft-start to limit inrush current.
If trickle charging is desired, please see the LTC4080
data sheet.
n
C/10 Charge Current Detection Output
n
5µA Supply Current in Shutdown Mode
Switching Regulator:
n
High Efficiency Synchronous Buck Converter
n
300mA Output Current (Constant-Frequency Mode)
n
2.7V to 4.5V Input Range (Powered from BAT Pin)
n
0.8V to V Output Range
BAT
n
The LTC4080X integrates a synchronous buck converter
thatispoweredfromtheBATpin.Ithasanadjustableoutput
voltage and can deliver up to 300mA of load current. The
buck converter also features low-current high-efficiency
BurstModeoperationthatcanbeselectedbytheMODEpin.
MODE Pin Selects Fixed (2.25MHz) Constant-Fre-
quency PWM Mode or Low I (23µA) Burst Mode®
CC
Operation
n
2µA BAT Current in Shutdown Mode
applicaTions
TheLTC4080Xisavailablein10-lead,lowprofile(0.75mm)
3mm × 3mm DFN and 10-lead MSE packages.
n
Wireless Headsets
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and
Burst Mode is a trademark of Linear Technology Corporation. All other trademarks are the
property of their respective owners. Protected by U.S. Patents, including 6522118.
n
Bluetooth Applications
Portable MP3 Players
n
n
Multifunction Wristwatches
Buck Efficiency vs Load Current
(VOUT = 1.8V)
Typical applicaTion
100
80
60
40
20
0
1000
100
10
Li-Ion Battery Charger with 1.8V Buck Regulator
500mA
EFFICIENCY
(Burst)
V
CC
V
BAT
EN_BUCK
SW
CC
4.2V
EFFICIENCY
(PWM)
(3.75V
to 5.5V)
+
Li-Ion/
POWER
LOSS
4.7µF
POLYMER
BATTERY
1OµH
(PWM)
LTC4080X
10pF
1M
4.7µF
1
V
OUT
POWER LOSS
EN_CHRG
FB
(1.8V/300mA)
(Burst)
MODE GND PROG
V
V
= 3.8V
= 1.8V
BAT
OUT
C
OUT
4.7µF
0.1
0.01
806Ω
806k
L = 10µH
C = 4.7µF
4080X TA01a
0.01
0.1
1
10
100
1000
LOAD CURRENT (mA)
4080X TA01b
4080Xfa
1
For more information www.linear.com/LTC4080X
LTC4080X
absoluTe maximum raTings
(Note 1)
BAT Short-Circuit Duration ...........................Continuous
BAT Pin Current .................................................. 800mA
PROG Pin Current ....................................................2mA
Junction Temperature ............................................125°C
Operating Temperature Range (Note 2)... – 40°C to 85°C
Storage Temperature Range ................. – 65°C to 125°C
V , t < 1ms and Duty Cycle < 1%.............. – 0.3V to 7V
CC
V
CC
Steady State......................................... – 0.3V to 6V
BAT, CHRG.................................................. – 0.3V to 6V
EN_CHRG, PROG, ACPR .................– 0.3V to V + 0.3V
CC
BAT
MODE, EN_BUCK.......................... – 0.3V to V
+ 0.3V
FB ............................................................... – 0.3V to 2V
pin conFiguraTion
TOP VIEW
TOP VIEW
BAT
1
2
3
4
5
10 SW
BAT
CC
EN_CHRG
1
2
3
4
5
10 SW
V
CC
9
8
7
6
EN_BUCK
V
9
8
7
6
EN_BUCK
11
11
MODE
FB
CHRG
EN_CHRG
PROG
MODE
FB
PROG
ACPR
ACPR
CHRG
MSE PACKAGE
10-LEAD PLASTIC MSOP
DD PACKAGE
10-LEAD (3mm × 3mm) PLASTIC DFN
T
= 125°C, θ = 40°C/W
JA
JMAX
EXPOSED PAD (PIN 11) I GND, MUST BE SOLDERED TO PCB
S
T
= 110°C, θ = 43°C/W (NOTE 3)
JA
EXPOSED PAD (PIN 11) I GND, MUST BE SOLDERED TO PCB
JMAX
S
orDer inFormaTion
LEAD FREE FINISH
TAPE AND REEL
PART MARKING
PACKAGE DESCRIPTION
TEMPERATURE RANGE
LTC4080XEDD#PBF
LTC4080XEMSE#PBF
LTC4080XEDD#TRPBF
LTC4080XEMSE#TRPBF LTCVW
LCVV
0°C to 70°C
0°C to 70°C
10-Lead (3mm × 3mm) DFN
10-Lead Plastic MSE
Consult LTC Marketing for parts specified with wider operating temperature ranges.
Consult LTC Marketing for information on non-standard lead based finish parts.
For more information on lead free part marking, go to: http://www.linear.com/leadfree/
For more information on tape and reel specifications, go to: http://www.linear.com/tapeandreel/
4080Xfa
2
For more information www.linear.com/LTC4080X
LTC4080X
elecTrical characTerisTics The ldenotes the specifications which apply over the full operating tempera-
ture range, otherwise specifications are at TA = 25°C. VCC = 5V, VBAT = 3.8V, VEN_CHRG = 0V, VEN_BUCK = VBAT, VMODE = 0V. (Note 2)
SYMBOL
PARAMETER
CONDITIONS
(Note 4)
MIN
TYP
MAX
5.5
UNITS
l
l
V
Battery Charger Supply Voltage
3.75
5
V
V
CC
V
BAT
Input Voltage for the Switching
Regulator
(Note 5)
2.7
3.8
4.5
300
10
l
l
I
I
Quiescent Supply Current (Charger On,
Switching Regulator Off)
V
V
= 4.5V (Forces I and I = 0),
PROG
EN_BUCK
110
µA
CC
BAT
BAT
= 0
Supply Current in Shutdown (Both
Battery Charger and Switching
Regulator Off)
V
V
V
= 5V, V
= 4V, V
= 0, V > V
BAT
5
2
µA
µA
CC_SD
EN_CHRG
EN_CHRG
BAT
EN_BUCK
EN_BUCK
CC
= 0, V (3.5V) <
CC
(4V)
l
I
Battery Current in Shutdown (Both
Battery Charger and Switching
Regulator Off)
V
V
V
= 5V, V
= 4V, V
= 0, V > V
BAT
0.6
2
5
µA
µA
BAT_SD
EN_CHRG
EN_CHRG
BAT
EN_BUCK
EN_BUCK
CC
= 0, V (3.5V) <
CC
(4V)
Battery Charger
V
V
Regulated Output Voltage
I
I
= 2mA
4.179
4.158
4.2
4.2
4.221
4.242
V
V
FLOAT
BAT
BAT
BAT
l
= 2mA, 4.3V < V < 5.5V
CC
l
l
I
Current Mode Charge Current
Undervoltage Lockout Voltage
R
R
= 4k; Current Mode; V
= 0
EN_BUCK
90
100
500
110
525
mA
mA
BAT
PROG
PROG
EN_BUCK
= 0.8k; Current Mode; V
= 0
475
l
l
V
V
V
V
Rising
Falling
3.5
2.8
3.6
3.0
3.7
3.2
V
V
UVLO_CHRG
CC
CC
CC
l
V
V
PROG Pin Servo Voltage
0.8k ≤ R
≤ 4k
0.98
1.0
1.02
V
PROG
PROG
Automatic Shutdown Threshold Voltage (V – V ), V Low to High
60
15
82
32
100
45
mV
mV
ASD
CC
BAT
BAT
CC
CC
(V – V ), V High to Low
CC
t
Battery Charger Soft-Start Time
Bad Battery Threshold Voltage
Recharge Battery Threshold Voltage
(V – V ) Undervoltage Current
Limit Threshold Voltage
Charge Termination Timer
Recharge Time
180
2.9
µs
V
SS_CHRG
V
BADBAT
V
I
– V , 0°C < T < 85°C
70
100
130
mV
DV
FLOAT
BAT
A
RECHRG
= 0.9 I
= 0.1 I
180
90
300
130
mV
mV
DV
DV
CC
BAT
BAT
BAT
CHG
CHG
UVCL1,
UVCL2
I
l
l
l
l
t
3
4.5
2.25
1.125
0.1
6
3
hrs
hrs
TIMER
1.5
Low-Battery Charge Time
End of Charge Indication Current Level
V
= 2.5V
0.75
0.085
1.5
0.115
hrs
BAT
I
R
= 2k (Note 6)
PROG
mA/mA
°C
C/10
T
Junction Temperature in Constant-
Temperature Mode
115
LIM
R
Power FET On-Resistance (Between
CC
I
= 350mA, V = 4V
750
2
mW
Hz
ON_CHRG
BADBAT
BAT
CC
V
and BAT)
f
Defective Battery Detection CHRG Pulse V = 2V
Frequency
BAT
D
Defective Battery Detection CHRG Pulse V = 2V
75
%
BADBAT
BAT
Frequency Duty Ratio
Buck Converter
l
l
V
FB Servo Voltage
0.78
–50
1.8
0.80
0.82
50
V
nA
FB
I
f
I
FB Pin Input Current
Switching Frequency
V = 0.85V
FB
FB
2.25
1.9
2.75
MHz
mA
OSC
No-Load Battery Current (Continuous
Frequency Mode)
No-Load for Regulator, V
L = 10µH, C = 4.7µF
= 5V,
EN_CHRG
BAT_NL_CF
4080Xfa
3
For more information www.linear.com/LTC4080X
LTC4080X
elecTrical characTerisTics The ldenotes the specifications which apply over the full operating tempera-
ture range, otherwise specifications are at TA = 25°C. VCC = 5V, VBAT = 3.8V, VEN_CHRG = 0V, VEN_BUCK = VBAT, VMODE = 0V. (Note 2)
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
23
MAX
UNITS
I
No-Load Battery Current (Burst Mode
Operation)
No-Load for Regulator, V
= 5V,
µA
µA
BAT_NL_BM
EN_CHRG
MODE = V , L = 10µH, C = 4.7µF
BAT
l
I
Battery Current in SLEEP Mode
V
V
= 5V, MODE = V
,
10
15
20
BAT_SLP
EN_CHRG
BAT
> Regulation Voltage
OUT
l
l
V
Buck Undervoltage Lockout Voltage
V
BAT
V
BAT
Rising
Falling
2.6
2.4
2.7
2.5
2.8
2.6
V
V
UVLO_BUCK
R
R
PMOS Switch On-Resistance
NMOS Switch On-Resistance
PMOS Switch Current Limit
NMOS Switch Current Limit
NMOS Zero Current in Normal Mode
0.95
0.85
520
700
15
W
W
ON_P
ON_N
I
I
I
I
I
t
375
700
mA
mA
mA
mA
mA
µs
LIM_P
LIM_N
ZERO_CF
PEAK
Peak Current in Burst Mode Operation MODE = V
50
20
100
35
150
50
BAT
Zero Current in Burst Mode Operation
Buck Soft-Start Time
MODE = V
ZERO_BM
SS_BUCK
BAT
From the Rising Edge of EN_BUCK to 90%
of Buck Regulated Output
400
Logic
l
l
l
l
l
V
V
V
Input High Voltage
EN_CHRG, EN_BUCK, MODE Pin Low to High
EN_CHRG, EN_BUCK, MODE Pin High to Low
1.2
V
V
IH
IL
Input Low Voltage
0.4
Output Low Voltage (CHRG, ACPR)
Input Current High
I
= 5mA
60
105
1
mV
µA
µA
MW
µA
µA
OL
SINK
I
IH
I
IL
EN_BUCK, MODE Pins at 5.5V, V = 5V
–1
–1
1
BAT
Input Current Low
EN_CHRG, EN_BUCK, MODE Pins at GND
1
R
EN_CHRG Pin Input Resistance
CHRG Pin Leakage Current
ACPR Pin Leakage Current
V
V
V
= 5V
EN_CHRG
1.45
3.3
1
EN_CHRG
CHRG
l
l
I
I
= 4.5V, V
= 5V
BAT
CHRG
= 3V, V = 5V
CHRG
1
ACPR
CC
Note 4: Although the LTC4080X charger functions properly at 3.75V, full
charge current requires an input voltage greater than the desired final
Note 1: Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
battery voltage per ∆V
specification.
UVCL1
Note 5: The 2.8V maximum buck undervoltage lockout (V ) exit
UVLO_BUCK
threshold must first be exceeded before the minimum V specification
applies.
Note 2: The LTC4080X is guaranteed to meet performance specifications
from 0°C to 85°C. Specifications over the –40°C to 85°C operating
temperature range are assured by design, characterization and correlation
with statistical process controls.
BAT
Note 6: I
is expressed as a fraction of measured full charge current
C/10
with indicated PROG resistor.
Note 3: Failure to solder the exposed backside of the package to the PC
board ground plane will result in a thermal resistance much higher than
43°C/W.
4080Xfa
4
For more information www.linear.com/LTC4080X
LTC4080X
Typical perFormance characTerisTics (TA = 25°C, VCC = 5V, VBAT = 3.8V, unless otherwise
specified)
Battery Regulation (Float) Voltage
vs Charge Current
Battery Regulation (Float) Voltage
vs Temperature
Battery Regulation (Float) Voltage
vs VCC Supply Voltage
4.21
4.20
4.19
4.18
4.17
4.16
4.15
4.14
4.13
4.210
4.205
4.200
4.195
4.190
4.185
4.180
4.175
4.170
4.165
4.160
4.25
R
PROG
= 2k
4.20
4.15
4.10
4.05
4.00
3.95
3.90
3.85
200
CHARGE CURRENT (mA)
250
–30 –10
30
50
70
90
4.5
5
6
0
50
100
150
–50
10
4
5.5
TEMPERATURE (°C)
V
SUPPLY VOLTAGE (V)
CC
4080X G01
4080X G03
4080X G02
Charge Current vs Temperature
with Thermal Regulation
(Constant-Current Mode)
Charger FET On-Resistance
vs Temperature
PROG Pin Voltage
vs Charge Current
250
200
150
100
50
1.0
0.8
0.6
0.4
0.2
0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
V
V
= 6V
CC
V
BAT
= 4V
= 350mA
R
= 2k
CC
PROG
= 3V
BAT
I
R
= 2k
PROG
THERMAL CONTROL
LOOP IN OPERATION
0
–25
0
25
50
75
25 50
125 150
–30 –10
30
50
70
90
–50
100 125
0
75 100
175 200
–50
10
TEMPERATURE (°C)
CHARGE CURRENT (mA)
TEMPERATURE (°C)
4080X G04
4080X G06
4080X G05
EN_CHRG, EN_BUCK and
MODE Pin Threshold Voltage
vs Temperature
EN_CHRG Pin Pull-down
Resistance vs Temperature
1.7
0.95
0.90
0.85
0.80
0.75
0.70
0.65
0.60
0.55
1.6
1.5
1.4
1.3
1.2
1.1
1.0
RISING
FALLING
0.50
–50 –30 –10 10
TEMPERATURE (°C)
90
30
50
70
–50 –30 –10 10
TEMPERATURE (°C)
90
30
50
70
4080X G07
4080X G08
4080Xfa
5
For more information www.linear.com/LTC4080X
LTC4080X
Typical perFormance characTerisTics (TA = 25°C, VCC = 5V, VBAT = 3.8V, unless otherwise
specified)
CHRG and ACPR Pin Output
Low Voltage vs Temperature
Normalized Charge Termination
Time vs Temperature
Buck Oscillator Frequency
vs Battery Voltage
80
1.05
1.00
0.95
0.90
0.85
0.80
2.28
2.27
2.26
2.25
2.24
I
, I
= 5mA
CHRG ACPR
70
60
50
40
30
20
10
2.23
2.22
0
–50 –30 –10 10
TEMPERATURE (°C)
90
30
50
70
3.0
3.5
4.5
–50 –30 –10 10
90
2.5
4.0
30
50
70
TEMPERATURE (°C)
BATTERY VOLTAGE (V)
4080X G09
4080X G10
4080X G11
Buck Oscillator Frequency
vs Temperature
Buck Efficiency vs Load Current
(VOUT = 1.8V)
Buck Efficiency vs Load Current
(VOUT = 1.5V)
100
80
60
40
20
0
1000
100
10
100
80
60
40
20
0
1000
2.4
2.3
2.2
2.1
2.0
1.9
1.8
V
= 3.8V
BAT
EFFICIENCY
(Burst)
V
= 4.5V
EFFICIENCY
(Burst)
BAT
100
10
EFFICIENCY
(PWM)
EFFICIENCY
(PWM)
POWER
POWER
LOSS
LOSS
V
= 2.7V
BAT
(PWM)
(PWM)
1
1
POWER LOSS
(Burst)
POWER LOSS
(Burst)
V
V
= 3.8V
= 1.5V
V
= 3.8V
= 1.8V
BAT
OUT
BAT
OUT
L = 10µH
0.1
0.01
0.1
0.01
V
L = 10µH
C = 4.7µF
C = 4.7µF
40 60
–60 –40 –20
0
20
80 100
0.01
0.1
1
10
100
1000
0.01
0.1
1
10
100
1000
TEMPERATURE (°C)
LOAD CURRENT (mA)
LOAD CURRENT (mA)
4080X G13a
4080X G12
4080X G13
No-Load Buck Input Current
(Burst Mode Operation)
vs Battery Voltage
Buck Output Voltage
vs Battery Voltage
Buck Output Voltage
vs Temperature
1.810
1.805
1.810
35
30
25
I
= 1mA
OUT
I
= 1mA
OUT
Burst Mode
OPERATION
OUT
OUT
I
= 1mA
= 1.8V
Burst Mode
OUT
OUT
V
SET FOR 1.8V
V
SET FOR 1.8V
V
OPERATION
1.805
1.800
1.795
L = 10µH
PWM MODE
PWM MODE
1.800
1.795
20
15
10
5
1.790
1.785
1.780
1.790
1.785
1.780
0
30
–50 –30 –10 10
TEMPERATURE (°C)
70
90
2.5
3.0
3.5
4.0
4.5
50
3.5
BATTERY VOLTAGE (V)
2.5
3.0
4.0
4.5
BATTERY VOLTAGE (V)
4080X G14
4080X G15
4080X G17
4080Xfa
6
For more information www.linear.com/LTC4080X
LTC4080X
Typical perFormance characTerisTics (TA = 25°C, VCC = 5V, VBAT = 3.8V, unless otherwise
specified)
No-Load Buck Input Current
(Burst Mode Operation)
vs Temperature
Buck Main Switch (PMOS)
On-Resistance vs Battery Voltage
Buck Main Switch (PMOS)
On-Resistance vs Temperature
35
30
1.2
1.0
0.8
0.6
0.4
0.2
0
1.2
1.0
0.8
0.6
0.4
0.2
0
L = 10mH
C = 4.7µF
OUT
V
= 4.2V
= 3.8V
BAT
V
= 1.8V
V
BAT
25
20
15
10
5
V
= 2.7V
BAT
0
30
TEMPERATURE (°C)
70
90
–50 –30 –10 10
50
30
TEMPERATURE (°C)
70
90
–50 –30 –10 10
50
3.5
BATTERY VOLTAGE (V)
2.5
3.0
4.0
4.5
5.0
4080X G18
4080X G20
4080X G19
Buck Synchronous Switch (NMOS)
On-Resistance vs Battery Voltage
Buck Synchronous Switch (NMOS)
On-Resistance vs Temperature
1.2
1.0
0.8
0.6
0.4
1.2
1.0
0.8
0.6
0.4
0.2
0
0.2
0
3.5
BATTERY VOLTAGE (V)
2.5
3.0
4.0
4.5
5.0
30
TEMPERATURE (°C)
70
90
–50 –30 –10 10
50
4080X G21
4080X G22
Maximum Output Current
(PWM Mode) vs Battery Voltage
Maximum Output Current (Burst
Mode Operation) vs Battery Voltage
500
400
300
200
100
80
70
60
50
40
30
20
10
0
L = 10µH
L = 10µH
V
SET FOR 1.8V
OUT
V
SET FOR 1.8V
OUT
2.7
3
3.3
3.6
3.9
4.2
4.5
2.7
3
3.3
3.6
3.9
4.2
4.5
BATTERY VOLTAGE (V)
BATTERY VOLTAGE (V)
4080X G24
4080X G23
4080Xfa
7
For more information www.linear.com/LTC4080X
LTC4080X
Typical perFormance characTerisTics (TA = 25°C, VCC = 5V, VBAT = 3.8V, unless otherwise
specified)
Output Voltage Waveform
when Switching Between Burst
and PWM Mode (ILOAD = 10mA)
Output Voltage Transient
Step Response (PWM Mode)
Output Voltage Transient
Step Response (Burst Mode)
V
V
V
OUT
OUT
OUT
50mV/DIV
20mV/DIV
20mV/DIV
AC COUPLED
AC COUPLED
AC COUPLED
I
I
V
LOAD
LOAD
MODE
50mA/DIV
I = 0
250mA/DIV
5V/DIV
I = 0
0V
4080X G26
4080X G25
4080X G27
50µs/DIV
50µs/DIV
50µs/DIV
Buck VOUT Soft-Start
(ILOAD = 50mA)
Charger VPROG Soft-Start
V
OUT
1V/DIV
0V
V
PROG
200mV/DIV
V
_
EN BUCK
V = 0
5V/DIV
0V
4080X G28
4080X G29
50µs/DIV
200µs/DIV
4080Xfa
8
For more information www.linear.com/LTC4080X
LTC4080X
pin FuncTions
BAT (Pin 1): Charge Current Output and Buck Regulator
Input. Provides charge current to the battery and regu-
lates the final float voltage to 4.2V. An internal precision
resistor divider from this pin sets the float voltage and is
disconnected in charger shutdown mode. This pin must
be decoupled with a low ESR capacitor for low-noise buck
operation.
old(3.6V)andgreaterthanV +82mV, theACPRpinwill
BAT
be pulled to ground; otherwise the pin is high impedance.
CHRG (Pin 6): Open-Drain Charge Status Output. The
charge status indicator pin has three states: pull-down,
high impedance state, and pulsing at 2Hz. This output can
be used as a logic interface or as an LED driver. When the
battery is being charged, the CHRG pin is pulled low by
an internal N-channel MOSFET. When the charge current
drops to 10% of the full-scale current, the CHRG pin is
forced to a high impedance state. When the battery volt-
age remains below 2.9V for one quarter of the full charge
time, the battery is considered defective, and the CHRG
pin pulses at a frequency of 2Hz with 75% duty cycle.
V (Pin2):PositiveInputSupplyVoltage.Thispinprovides
CC
power to the battery charger. V can range from 3.75V
CC
to 5.5V. This pin should be bypassed with at least a 1µF
capacitor. When V is less than 32mV above the BAT
CC
pin voltage, the battery charger enters shutdown mode.
EN_CHRG(Pin3):EnableInputPinfortheBatteryCharger.
Pullingthispinabovethemanualshutdownthreshold(V )
FB(Pin7):FeedbackPinfortheBuckRegulator. Aresistor
divider from the regulator’s output to the FB pin programs
the output voltage. Servo value for this pin is 0.8V.
IH
putstheLTC4080Xchargerinshutdownmode, thusstop-
ping the charge cycle. In battery charger shutdown mode,
the LTC4080X has less than 10µA supply current and less
than 5µA battery drain current provided the regulator is
not running. Enable is the default state, but the pin should
be tied to GND if unused.
MODE (Pin 8): Burst Mode Enable Pin. Tie this pin high to
force the LTC4080X regulator into Burst Mode operation
for all load conditions. Tie this pin low to force constant-
frequency mode operation for all load conditions. Do not
float this pin.
PROG (Pin 4): Charge Current Program and Charge Cur-
rent Monitor Pin. Connecting a 1% resistor, R
ground programs the charge current. When charging in
constant-currentmode,thispinservosto1V.Inallmodes,
the voltage on this pin can be used to measure the charge
current using the following formula:
, to
PROG
EN_BUCK(Pin9):EnableInputPinfortheBuckRegulator.
Pull this pin high to enable the regulator, pull low to shut
down. Do not float this pin.
SW (Pin 10): Switch Pin for the Buck Regulator. Minimize
the length of the metal trace connected to this pin. Place
the inductor as close to this pin as possible.
V
PROG
IBAT
=
• 400
RPROG
GND (Pin 11): Ground. This pin is the back of the Exposed
PadpackageandmustbesolderedtothePCBforelectrical
connection and rated thermal performance.
ACPR (Pin 5): Open-Drain Power Supply Status Output.
WhenV isgreaterthantheundervoltagelockoutthresh-
CC
4080Xfa
9
For more information www.linear.com/LTC4080X
LTC4080X
block Diagram
2
V
CC
+
3
CHARGER
SHUTDOWN
EN_CHRG
C3
MP3
X1
MP1
115°C
–
+
D3
–
0.82V
TA
X400
R
EN
T
DIE
D1
D2
PROG
0.1V
1
BAT
–
+
+
–
MA
C1
R1
R2
CA
VA
–
+
+
–
MP4
6
1.22V
1V
CHRG
CHARGER
ENABLE
PULSE
LOGIC
+
–
2.9V
BAT
C2
CHARGE
CONTROL
BADBAT
4
5
LOGIC
PROG
R
PROG
+
–
V
CC
C4
C5
CHARGER
OSCILLATOR
COUNTER
3.6V
ACPR
+
–
V
+ 82mV
BAT
LINEAR BATTERY CHARGER
MP2
+
–
SYNCHRONOUS BUCK CONVERTER
9
8
L1
PWM
V
C
OUT
EN_BUCK
ENABLE BUCK
C6
10
7
CONTROL
AND DRIVE
SW
MN1
0.82V
C
R7
R8
PL
–
+
–
OUT
2.25MHz
BUCK
OSCILLATOR
ERROR
MODE
FB
C7
AMP
+
0.8V
0.82V
11
4080X BD
GND
Figure 1. LTC4080X Block Diagram
4080Xfa
10
For more information www.linear.com/LTC4080X
LTC4080X
operaTion
The LTC4080X is a full-featured linear battery charger
with an integrated synchronous buck converter designed
primarily for handheld applications. The battery charger is
capable of charging single-cell 4.2V Li-Ion batteries. The
buck converter is powered from the BAT pin and has a
programmable output voltage providing a maximum load
current of 300mA. The converter and the battery charger
can run simultaneously or independently of each other.
thermal limit is that charge current can be set according
to typical, rather than worst-case, ambient temperatures
for a given application with the assurance that the battery
chargerwillautomaticallyreducethecurrentinworst-case
conditions.
An internal timer sets the total charge time, t
(typi-
TIMER
cally 4.5 hours). When this time elapses, the charge cycle
terminates and the CHRG pin assumes a high impedance
state even if C/10 has not yet been reached. To restart
the charge cycle, remove the input voltage and reapply
BATTERY CHARGER OPERATION
it or momentarily force the EN_CHRG pin above V . A
IH
Featuring an internal P-channel power MOSFET, MP1, the
battery charger uses a constant-current/constant-voltage
charge algorithm with programmable current. Charge
current can be programmed up to 500mA with a final
float voltage of 4.2V 0.5%. The CHRG open-drain status
outputindicateswhenC/10hasbeenreached. Noblocking
diodeorexternalsenseresistorisrequired;thus, thebasic
chargercircuitrequiresonlytwoexternalcomponents.The
ACPR open-drain output indicates if the V input voltage,
and the difference between V and BAT, are sufficient for
charging. An internal charge termination timer adheres to
battery manufacturer safety guidelines. Furthermore, the
LTC4080X battery charger is capable of operating from a
USB power source.
new charge cycle will automatically restart if the BAT pin
voltage falls below V
(typically 4.1V).
RECHRG
Constant-Current / Constant-Voltage /
Constant-Temperature
The LTC4080X battery charger uses a unique architecture
tochargeabatteryinaconstant-current,constant-voltage
andconstant-temperaturefashion.Figure1showsaSimpli-
fied Block Diagram of the LTC4080X. Three of the ampli-
fier feedback loops shown control the constant-current,
CA, constant-voltage, VA, and constant-temperature, TA
modes. A fourth amplifier feedback loop, MA, is used to
increase the output impedance of the current source pair,
MP1 and MP3 (note that MP1 is the internal P-channel
power MOSFET). It ensures that the drain current of MP1
is exactly 400 times the drain current of MP3.
CC
CC
A charge cycle begins when the voltage at the V pin
CC
rises above 3.6V and approximately 82mV above the BAT
pin voltage, a 1% program resistor is connected from the
PROGpintoground,andtheEN_CHRGpinispulledbelow
Amplifiers CA and VA are used in separate feedback loops
to force the charger into constant-current or constant-
voltage mode, respectively. Diodes D1 and D2 provide
priority to either the constant-current or constant-voltage
loop, whichever is trying to reduce the charge current
the most. The output of the other amplifier saturates low
which effectively removes its loop from the system. When
in constant-current mode, CA servos the voltage at the
PROG pin to be precisely 1V. VA servos its non-inverting
input to 1.22V when in constant-voltage mode and the
internal resistor divider made up of R1 and R2 ensures
that the battery voltage is maintained at 4.2V. The PROG
pin voltage gives an indication of the charge current any-
time in the charge cycle, as discussed in “Programming
Charge Current” in the Applications Information section.
the shutdown threshold (V ).
IL
When the BAT pin approaches the final float voltage of
4.2V, the battery charger enters constant-voltage mode
and the charge current begins to decrease. When the
current drops to 10% of the full-scale charge current, an
internal comparator turns off the N-channel MOSFET driv-
ing the CHRG pin, and the pin becomes high impedance.
An internal thermal limit reduces the programmed charge
current if the die temperature attempts to rise above a
presetvalueofapproximately115°C. Thisfeatureprotects
the LTC4080X from excessive temperature and allows the
user to push the limits of the power handling capability
of a given circuit board without the risk of damaging the
LTC4080Xorexternalcomponents. Anotherbenefitofthe
4080Xfa
11
For more information www.linear.com/LTC4080X
LTC4080X
operaTion
If the die temperature starts to creep up above 115°C
due to internal power dissipation, the transconductance
amplifier, TA, limits the die temperature to approximately
115°C by reducing the charge current. Diode D3 ensures
that TA does not affect the charge current when the die
temperature is below 115°C. In thermal regulation, the
PROG pin voltage continues to give an indication of the
charge current.
the battery voltage rises above 2.9V, the charge cycle will
be restarted. To restart the charge cycle (i.e., when the
dead battery is replaced with a discharged battery less
than 2.9V), the charger must be reset by removing the
input voltage and reapplying it or temporarily pulling the
EN_CHRG pin above the shutdown threshold.
Battery Charger Shutdown Mode
TheLTC4080X’sbatterychargercanbedisabledbypulling
In typical operation, the charge cycle begins in constant-
currentmodewiththecurrentdeliveredtothebatteryequal
the EN_CHRG pin above the shutdown threshold (V ).
IH
In shutdown mode, the battery drain current is reduced
to 400V/R
. If the power dissipation of the LTC4080X
PROG
to about 2µA and the V supply current to about 5µA
resultsinthejunctiontemperatureapproaching115°C,the
amplifier (TA) will begin decreasing the charge current to
limit the die temperature to approximately 115°C. As the
battery voltage rises, the LTC4080X either returns to full
constant-current mode or enters constant-voltage mode
straight from constant-temperature mode.
CC
provided the regulator is off. When the input voltage is
not present, the battery charger is in shutdown and the
battery drain current is less than 5µA.
Power Supply Status Indicator (ACPR)
The power supply status output has two states: pull-down
and high impedance. The pull-down state indicates that
CC
least 82mV above the BAT voltage (see Undervoltage
Lockout). When these conditions are not met, the ACPR
pin is high impedance indicating that the LTC4080X is
unable to charge the battery.
Battery Charger Undervoltage Lockout (UVLO)
V
is above the undervoltage lockout threshold and at
An internal undervoltage lockout circuit monitors the V
input voltage and keeps the battery charger off until V
CC
CC
rises above 3.6V and approximately 82mV above the BAT
pinvoltage. The3.6VUVLOcircuithasabuilt-inhysteresis
ofapproximately0.6V,andthe82mVautomaticshutdown
thresholdhasabuilt-inhysteresisofapproximately50mV.
Duringundervoltagelockoutconditions,maximumbattery
draincurrentis5µAandmaximumsupplycurrentis10µA.
CHRG Status Output Pin
Thechargestatusindicatorpinhasthreestates:pull-down,
pulsing at 2Hz (see Defective Battery Detection) and high
impedance. The pull-down state indicates that the bat-
tery charger is in a charge cycle. A high impedance state
indicates that the charge current has dropped below 10%
of the full-scale current or the battery charger is disabled.
When the timer runs out (4.5 hrs), the CHRG pin is also
forced to the high impedance state. If the battery charger
is not in constant-voltage mode when the charge current
is forced to drop below 10% of the full-scale current by
UVCL, CHRG will stay in the strong pull-down state.
Undervoltage Charge Current Limiting (UVCL)
ThebatterychargerintheLTC4080Xincludesundervoltage
charge current limiting that prevents full charge current
untiltheinputsupplyvoltagereachesapproximately300mV
abovethebatteryvoltage(DVUVCL1).Thisfeatureispartic-
ularlyusefuliftheLTC4080Xispoweredfromasupplywith
long leads (or any relatively high output impedance). See
Applications Information section for further details.
Defective Battery Detection
Charge Current Soft-Start
At the beginning of a charge cycle, if the battery voltage
is below 2.9V for one quarter of the total charge time
(1.125 hr), the battery is assumed to be defective, the
charge cycle terminates and the CHRG output pulses at a
frequency of 2Hz with a 75% duty cycle. If, for any reason,
TheLTC4080X’sbatterychargerincludesasoft-startcircuit
to minimize the inrush current at the start of a charge
cycle. When a charge cycle is initiated, the charge current
ramps from zero to full-scale current over a period of
4080Xfa
12
For more information www.linear.com/LTC4080X
LTC4080X
operaTion
approximately180µs.Thishastheeffectofminimizingthe
transientcurrentloadonthepowersupplyduringstart-up.
is less than the 0.8V reference voltage. The current into
the inductor (and the load) increases until it reaches the
peak current demanded by the error amp. At this point,
the main switch turns off and the synchronous switch
MN1 (N-channel MOSFET) turns on allowing the inductor
current to flow from ground to the load until either the
next clock cycle begins or the current reduces to the zero
Timer and Recharge
The LTC4080X’s battery charger has an internal charge
termination timer that starts when the input voltage is
greater than the undervoltage lockout threshold and at
least 82mV above BAT, and the battery charger is leaving
shutdown.
current (I
) level.
ZERO
Oscillator: In constant-frequency mode, the switching
regulator uses a dedicated oscillator which runs at a
fixed frequency of 2.25MHz. This frequency is chosen to
minimize possible interference with the AM radio band.
At power-up or when exiting shutdown, the charge time
is set to 4.5 hours. Once the charge cycle terminates, the
batterychargercontinuouslymonitorstheBATpinvoltage
using a comparator with a 2ms filter time. When the aver-
age battery voltage falls below 4.1V (which corresponds
to 80%-90% battery capacity), a new charge cycle is initi-
ated and a 2.25 hour timer begins. This ensures that the
battery is kept at, or near, a fully charged condition and
eliminates the need for periodic charge cycle initiations.
The CHRG output assumes a strong pull-down state dur-
ing recharge cycles until C/10 is reached or the recharge
cycle terminates.
Error Amplifier: The error amplifier is an internally com-
pensated transconductance (g ) amplifier with a g of
m
m
65µmhos. The internal 0.8V reference voltage is com-
pared to the voltage at the FB pin to generate a current
signal at the output of the error amplifier. This current
signal represents the peak inductor current required to
achieve regulation.
PWM Comparator: Lossless current sensing converts
the PMOS switch current signal to a voltage which is
summed with the internal slope compensation signal.
The PWM comparator compares this summed signal to
determine when to turn off the main switch. The switch
current sensing is blanked for ~12ns at the beginning of
each clock cycle to prevent false switch turn-off.
SWITCHING REGULATOR OPERATION:
The switching buck regulator in the LTC4080X can be
turnedonbypullingtheEN_BUCKpinaboveV .Ithastwo
IH
user-selectable modes of operation: constant-frequency
(PWM) mode and Burst Mode Operation. The constant-
frequency mode operation offers low noise at the expense
of efficiency whereas the Burst Mode operation offers
higher efficiency at light loads at the cost of increased
noise, higher output voltage ripple, and less output cur-
rent. A detailed description of different operating modes
and different aspects of operation follow. Operations can
best be understood by referring to the Block Diagram.
Burst Mode Operation
Burst Mode operation can be selected by pulling the
MODE pin above V . In this mode, the internal oscil-
IH
lator is disabled, the error amplifier is converted into a
comparator monitoring the FB voltage, and the inductor
current swings between a fixed I
(~100mA) and I
ZERO
PEAK
(35mA) irrespective of the load current as long as the FB
pin voltage is less than or equal to the reference voltage
Constant-Frequency (PWM) Mode Operation
of 0.8V. Once V is greater than 0.8V, the control logic
FB
shuts off both switches along with most of the circuitry
and the regulator is said to enter into SLEEP mode. In
SLEEP mode, the regulator only draws about 20µA from
the BAT pin provided that the battery charger is turned
off. When the output voltage droops about 1% from its
nominal value, the regulator wakes up and the inductor
The switching regulator operates in constant-frequency
(PWM) mode when the MODE pin is pulled below V . In
IL
this mode, it uses a current mode architecture including
an oscillator, an error amplifier, and a PWM comparator
for excellent line and load regulation. The main switch
MP2 (P-channel MOSFET) turns on to charge the inductor
at the beginning of each clock cycle if the FB pin voltage
current resumes swinging between I
and I
. The
PEAK
ZERO
4080Xfa
13
For more information www.linear.com/LTC4080X
LTC4080X
operaTion
output capacitor recharges and causes the regulator to
re-enter the SLEEP state if the output load remains light
enough. Thefrequencyofthisintermittentburstoperation
depends on the load current. That is, as the load current
drops further, the regulator turns on less frequently. Thus
Burst Mode operation increases the efficiency at light
loads by minimizing the switching and quiescent losses.
However, the output voltage ripple increases to about 2%.
However, in Burst Mode operation, I
is set to positive
ZERO
35mA meaning that the synchronous switch is turned off
as soon as the current through the inductor to the output
decreases to 35mA in the discharge cycle. This preserves
thechargeontheoutputcapacitorandincreasestheoverall
efficiency at light loads.
Soft-Start
The LTC4080X switching regulator provides soft-start in
both modes of operation by slowly charging an internal
capacitor. The voltage on this capacitor, in turn, slowly
ramps the current limits of both switches from a low value
to their respective maximum values over a period of about
400µs. The soft-start capacitor is discharged completely
whenever the regulator is disabled.
To minimize ripple in the output voltage, the current limits
for both switches in Burst Mode operation are reduced
to about 20% of their values in the constant-frequency
mode. Also the zero current of the synchronous switch
is changed to about 35mA thereby preventing reverse
conductionthroughtheinductor.Consequently,theregula-
tor can only deliver approximately 67mA of load current
while in Burst Mode operation. Any attempt to draw more
load current will cause the output voltage to drop out of
regulation.
Short-Circuit Protection
In the event of a short circuit at the output or during
start-up, V
will be near zero volts. Since the downward
OUT
Current Limit
slope of the inductor current is ~V /L, the inductor
OUT
current may not get a chance to discharge enough to
avoid a runaway situation. Because the current sensing
is blanked for ~12ns at the beginning of each clock cycle,
inductor current can build up to a dangerously high level
over a number of cycles even if there is a hard current
limit on the main PMOS switch. This is why the switching
regulator in the LTC4080X also monitors current through
the synchronous NMOS switch and imposes a hard limit
on it. If the inductor current through the NMOS switch at
the end of a discharge cycle is not below this limit, the
regulator skips the next charging cycle thereby preventing
inductor current runaway.
To prevent inductor current runaway, there are absolute
current limits (I ) on both the PMOS main switch and
LIM
the NMOS synchronous switch. These limits are internally
set at 520mA and 700mA respectively for PWM mode. If
the peak inductor current demanded by the error amplifier
ever exceeds the PMOS I , the error amplifier will be
LIM
ignored and the inductor current will be limited to PMOS
I
. In Burst Mode operation, the PMOS current limit
LIM
is reduced to 100mA to minimize output voltage ripple.
Zero Current Comparator
Thezeroorreversecurrentcomparatormonitorstheinduc-
tor current to the output and shuts off the synchronous
rectifier when this current reduces to a predetermined
Switching Regulator Undervoltage Lockout
Whenever V
is less than 2.7V, an undervoltage lock-
value (I
). In fixed frequency mode, this is set to nega-
ZERO
BAT
out circuit keeps the regulator off, preventing unreliable
operation. However, if the regulator is already running
and the battery voltage is dropping, the undervoltage
tive 15mA meaning that the regulator allows the inductor
current to flow in the reverse direction (from the output to
ground through the synchronous rectifier) to a maximum
value of 15mA. This is done to ensure that the regulator
is able to regulate at very light loads without skipping any
cyclestherebykeepingoutputvoltagerippleandnoiselow
at the cost of efficiency.
comparator does not shut down the regulator until V
BAT
drops below 2.5V.
4080Xfa
14
For more information www.linear.com/LTC4080X
LTC4080X
operaTion
Dropout Operation
Global Thermal Shutdown
When the BAT pin voltage approaches V , the duty cycle
The LTC4080X includes a global thermal shutdown which
shuts off the entire device (battery charger and switch-
ing regulator) if the die temperature exceeds 160°C. The
LTC4080Xresumesnormaloperationoncethetemperature
drops approximately 14°C.
OUT
of the switching regulator approaches 100%. When V
BAT
is approximately equal to V , the regulator is said to be
OUT
in dropout. In dropout, the main switch (MP2) stays on
continuously with the output voltage being equal to the
battery voltage minus the voltage drops across the main
switch and the inductor.
applicaTions inFormaTion
BATTERY CHARGER
the additional pole created by PROG pin capacitance,
capacitance on this pin must be kept to a minimum. With
no additional capacitance on the PROG pin, the battery
charger is stable with program resistor values as high
as 25k. However, additional capacitance on this node
reduces the maximum allowed program resistor. The pole
frequency at the PROG pin should be kept above 100kHz.
Therefore, if the PROG pin is loaded with a capacitance,
Programming Charge Current
The battery charge current is programmed using a single
resistor from the PROG pin to ground. The charge current
is400timesthecurrentoutofthePROGpin. Theprogram
resistor and the charge current are calculated using the
following equations:
C
, the following equation should be used to calculate
PROG
1V
IBAT
1V
RPROG
the maximum resistance value for R
:
RPROG = 400 •
, IBAT = 400 •
PROG
1
RPROG
≤
The charge current out of the BAT pin can be determined
at any time by monitoring the PROG pin voltage and using
the following equation:
2π •100kHz •CPROG
Average,ratherthaninstantaneous,batterycurrentmaybe
of interest to the user. For example, when the switching
regulator operating in low-current mode is connected in
parallel with the battery, the average current being pulled
out of the BAT pin is typically of more interest than the
instantaneous current pulses. In such a case, a simple RC
filter can be used on the PROG pin to measure the average
battery current as shown in Figure 2. A 10k resistor has
been added between the PROG pin and the filter capacitor
to ensure stability.
V
PROG
IBAT
=
• 400
RPROG
Stability Considerations
TheLTC4080Xbatterychargercontainstwocontrolloops:
constant-voltage and constant-current. The constant-
voltage loop is stable without any compensation when a
battery is connected with low impedance leads. Excessive
lead length, however, may add enough series inductance
LTC4080X
CHARGE
to require a bypass capacitor of at least 1µF from BAT to
10k
CURRENT
PROG
GND. Furthermore, a 4.7µF capacitor with a 0.2W to 1W
series resistor from BAT to GND is required to keep ripple
voltage low when the battery is disconnected.
MONITOR
GND
CIRCUITRY
R
C
FILTER
PROG
4080X F02
In constant-current mode, the PROG pin voltage is in
the feedback loop, not the battery voltage. Because of
Figure 2. Isolating Capacitive Load
on PROG Pin and Filtering
4080Xfa
15
For more information www.linear.com/LTC4080X
LTC4080X
applicaTions inFormaTion
Undervoltage Charge Current Limiting (UVCL)
times improvement over the non-current limited supply
power dissipation.
USB powered systems tend to have highly variable source
impedances (due primarily to cable quality and length). A
transient load combined with such impedance can easily
triptheUVLOthresholdandturnthebatterychargeroffun-
less undervoltage charge current limiting is implemented.
USB and Wall Adapter Power
Although the LTC4080X allows charging from a USB port,
a wall adapter can also be used to charge Li-Ion batter-
ies. Figure 3 shows an example of how to combine wall
adapter and USB power inputs. A P-channel MOSFET,
MP1, is used to prevent back conducting into the USB
port when a wall adapter is present and Schottky diode,
D1, is used to prevent USB power loss through the 1k
pull-down resistor.
ConsiderasituationwheretheLTC4080Xisoperatingunder
normal conditions and the input supply voltage begins to
sag (e.g. an external load drags the input supply down).
If the input voltage reaches V
(approximately 300mV
), undervoltage charge
UVCL
above the battery voltage, DV
UVCL
current limiting will begin to reduce the charge current in
an attempt to maintain DV between V and BAT. The
Typically a wall adapter can supply significantly more
current than the current-limited USB port. Therefore, an
N-channel MOSFET, MN1, and an extra program resistor
can be used to increase the charge current when the wall
adapter is present.
UVCL
CC
LTC4080X will continue to operate at the reduced charge
current until the input supply voltage is increased or volt-
age mode reduces the charge current further.
Operation from Current Limited Wall Adapter
I
5V WALL
ADAPTER
(300mA)
CHG
1
SYSTEM
LOAD
BAT
LTC4080X
D1
2
By using a current limited wall adapter as the input sup-
ply, the LTC4080X can dissipate significantly less power
when programmed for a current higher than the limit of
the wall adapter.
USB
POWER
(200mA)
V
CC
4
+
Li-Ion
BATTERY
MP1
PROG
1.33k
MN1
2k
Considerasituationwhereanapplicationrequiresa200mA
charge current for a discharged 800mAh Li-Ion battery.
If a typical 5V (non-current limited) input supply is avail-
able then the peak power dissipation inside the part can
exceed 300mW.
1k
4080X F03
Figure 3. Combining Wall Adapter and USB Power
Power Dissipation
Now consider the same scenario, but with a 5V input
supply with a 200mA current limit. To take advantage
of the supply, it is necessary to program the LTC4080X
to charge at a current greater than 200mA. Assume that
the LTC4080X charger is programmed for 300mA (i.e.,
The conditions that cause the LTC4080X battery charger
to reduce charge current through thermal feedback can be
approximated by considering the total power dissipated
in the IC. For high charge currents, the LTC4080X power
dissipation is approximately:
R
= 1.33kW) to ensure that part tolerances maintain
PROG
a programmed current higher than 200mA. Since the
battery charger will demand a charge current higher than
the current limit of the input supply, the supply voltage
will collapse to the battery voltage plus 200mA times the
on-resistance of the internal PFET. The on-resistance of
the battery charger power device is approximately 0.75W
with a 5V supply. The actual on-resistance will be slightly
higher due to the fact that the input supply will have col-
lapsed to less than 5V. The power dissipated during this
phase of charging is approximately 30mW. That is a ten
P = V – V
•I + P
BAT
D_BUCK
D
BAT
CC
Where P is the total power dissipated within the IC, V
D
CC
BAT
istheinputsupplyvoltage, V isthebatteryvoltage, I
BAT
D_BUCK
is the charge current and P
due to the regulator. P
is the power dissipation
can be calculated as:
D_BUCK
1
h
P
= VOUT •IOUT
– 1
D_BUCK
4080Xfa
16
For more information www.linear.com/LTC4080X
LTC4080X
applicaTions inFormaTion
Where V
is the regulated output of the switching
OUT
V
Bypass Capacitor
CC
OUT
regulator, I
is the regulator load and h is the regulator
Many types of capacitors can be used for input bypassing;
however, caution must be exercised when using multi-layer
ceramic capacitors. Because of the self-resonant and high
Q characteristics of some types of ceramic capacitors, high
voltage transients can be generated under some start-up
conditions, such as connecting the battery charger input to
a live power source. Adding a 1
with an X5R ceramic capacitor will minimize start-up voltage
transients. For more information, refer to Application Note 88.
efficiency at that particular load.
It is not necessary to perform worst-case power dissipa-
tion scenarios because the LTC4080X will automatically
reduce the charge current to maintain the die temperature
at approximately 115°C. However, the approximate ambi-
ent temperature at which the thermal feedback begins to
protect the IC is:
W series resistor in series
T = 115°C – PDθJA
A
T = 115°C – (V – V ) • I
• θJA if the regulator
A
CC
BAT
BAT
SWITCHING REGULATOR
is off.
Example: Consider the extreme case when an LTC4080X
is operating from a 6V supply providing 250mA to a 3V
Li-Ion battery and the regulator is off. The ambient tem-
perature above which the LTC4080X will begin to reduce
the 250mA charge current is approximately:
Setting the Buck Converter Output Voltage
TheLTC4080XregulatorcomparestheFBpinvoltagewith
aninternal0.8Vreferencetogenerateanerrorsignalatthe
output of the error amplifier. A voltage divider from V
to ground (as shown in the Block Diagram) programs the
output voltage via FB using the formula:
OUT
T = 115°C – (6V – 3V) • (250mA) • 43°C/W
A
T = 115°C – 0.75W • 43°C/W = 115°C – 32.25°C
A
R7
R8
VOUT = 0.8V • 1+
T = 82.75°C
A
If there is more power dissipation due to the regulator,
the thermal regulation will begin at a somewhat lower
temperature. In the above circumstances, the LTC4080X
can be used above 82.75°C, but the charge current will be
reduced from 250mA. The approximate current at a given
ambient temperature can be calculated:
Keeping the current low (<5µA) in these resistors maxi-
mizes efficiency, but making them too low may allow stray
capacitancetocausenoiseproblemsandreducethephase
margin of the error amp loop. To improve the frequency
response, a phase-lead capacitor (C ) of approximately
PL
10pF can be used. Great care should be taken to route the
FB line away from noise sources, such as the inductor or
the SW line.
115°C – TA
IBAT
=
V – V
• θ
(
)
BAT
JA
CC
Usingthepreviousexamplewithanambienttemperatureof
85°C, thechargecurrentwillbereducedtoapproximately:
Inductor Selection
The value of the inductor primarily determines the cur-
rent ripple in the inductor. The inductor ripple cur-
115°C – 85°C
30°C
IBAT
=
=
= 232.6mA
6V – 3V • 43°C / W 129°C / A
(
)
rent DI decreases with higher inductance and
L
increases with higher V or V
:
IN
OUT
Furthermore, the voltage at the PROG pin will change
proportionally with the charge current as discussed in
the Programming Charge Current section.
VOUT
f0 •L
VOUT
∆IL =
• 1–
V
IN
Accepting larger values of DI allows the use of low
L
inductances, but results in higher output voltage ripple,
greater core losses, and lower output current capability.
4080Xfa
17
For more information www.linear.com/LTC4080X
LTC4080X
Typical applicaTions
A reasonable starting point for setting ripple current is
To prevent large V
voltage steps during transient
OUT
DI = 0.3 • I , where I is the peak switch current
load conditions, it is also recommended that a ceramic
L
LIM
LIM
limit. The largest ripple current occurs at the maximum
input voltage. To guarantee that the ripple current stays
below a specified maximum, the inductor value should be
chosen according to the following equation:
capacitor be used to bypass V . A typical value for this
OUT
capacitor is 4.7µF.
Multilayer Ceramic Chip Capacitors (MLCC) typically have
exceptional ESR performance. MLCCs combined with a
carefully laid out board with an unbroken ground plane
will yield very good performance and low EMI emissions.
VOUT
f0 • ∆IL
VOUT
L ≥
• 1–
V
IN(MAX)
Thereareseveraltypesofceramiccapacitorswithconsider-
ablydifferentcharacteristics.Y5Vceramiccapacitorshave
apparently higher packing density but poor performance
over their rated voltage or temperature ranges. Under
given voltage and temperature conditions, X5R and X7R
ceramic capacitors should be compared directly by case
size rather than specified value for a desired minimum
capacitance. Some manufacturers provide excellent data
on their websites about achievable capacitance. Table 2
shows a list of several ceramic capacitor manufacturers.
For applications with V
suggests that an inductor of at least 6.8µH should be used
for proper operation.
= 1.8V, the above equation
OUT
Many different sizes and shapes of inductors are
available from numerous manufacturers. To maximize
efficiency, choose an inductor with a low DC resistance.
Keep in mind that most inductors that are very thin or
have a very small volume typically have much higher
core and DCR losses and will not give the best efficiency.
Also choose an inductor with a DC current rating at least
1.5 times larger than the peak inductor current limit to
ensure that the inductor does not saturate during nor-
mal operation. To minimize radiated noise, use a toroid,
or shielded pot core inductors in ferrite or permalloy
materials. Table 1 shows a list of several inductor manu-
facturers.
Table 2. Recommended Ceramic Capacitor Manufacturers
Taiyo Yuden
AVX
www.t-yuden.com
www.avxcorp.com
www.murata.com
www.tdk.com
Murata
TDK
Board Layout Considerations
Table 1. Recommended Surface Mount Inductor Manufacturers
Coilcraft
Sumida
Murata
Toko
www.coilcraft.com
www.sumida.com
www.murata.com
www.tokoam.com
To be able to deliver maximum charge current under all
conditions, it is critical that the exposed metal pad on the
backside of the LTC4080X’s package has a good thermal
contact to the PC board ground. Correctly soldered to a
2
2500mm double-sided1oz.copperboard,theLTC4080X
Input and Output Capacitor Selection
hasathermalresistanceofapproximately43°C/W. Failure
to make thermal contact between the exposed pad on the
backside of the package and the copper board will result
in thermal resistances far greater than 43°C/W.
Since the input current waveform to a buck converter is a
squarewave,itcontainsveryhighfrequencycomponents.
It is strongly recommended that a low equivalent series
resistance (ESR) multilayer ceramic capacitor be used to
bypass the BAT pin which is the input for the converter.
Tantalum and aluminum capacitors are not recommended
because of their high ESR. The value of the capacitor on
BATdirectlycontrolstheamountofinputvoltageripplefor
a given load current. Increasing the size of this capacitor
will reduce the input ripple.
Furthermore due to its high frequency switching circuitry,
it is imperative that the input capacitor, BAT pin capaci-
tor, inductor, and the output capacitor be as close to the
LTC4080Xaspossibleandthatthereisanunbrokenground
plane under the LTC4080X and all of its high frequency
components.
4080Xfa
18
For more information www.linear.com/LTC4080X
LTC4080X
package DescripTion
Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings.
DD Package
10-Lead Plastic DFN (3mm × 3mm)
(Reference LTC DWG # 05-08-1699 Rev C)
0.70 ±0.05
3.55 ±0.05
2.15 ±0.05 (2 SIDES)
1.65 ±0.05
PACKAGE
OUTLINE
0.25 ±0.05
0.50
BSC
2.38 ±0.05
(2 SIDES)
RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS
R = 0.125
0.40 ±0.10
TYP
6
10
3.00 ±0.10
(4 SIDES)
1.65 ±0.10
(2 SIDES)
PIN 1 NOTCH
R = 0.20 OR
PIN 1
TOP MARK
(SEE NOTE 6)
0.35 × 45°
CHAMFER
(DD) DFN REV C 0310
5
1
0.25 ±0.05
0.50 BSC
0.75 ±0.05
0.200 REF
2.38 ±0.10
(2 SIDES)
0.00 – 0.05
BOTTOM VIEW—EXPOSED PAD
NOTE:
1. DRAWING TO BE MADE A JEDEC PACKAGE OUTLINE M0-229 VARIATION OF (WEED-2).
CHECK THE LTC WEBSITE DATA SHEET FOR CURRENT STATUS OF VARIATION ASSIGNMENT
2. DRAWING NOT TO SCALE
3. ALL DIMENSIONS ARE IN MILLIMETERS
4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE
MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.15mm ON ANY SIDE
5. EXPOSED PAD SHALL BE SOLDER PLATED
6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION ON THE
TOP AND BOTTOM OF PACKAGE
4080Xfa
19
For more information www.linear.com/LTC4080X
LTC4080X
package DescripTion
Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings.
MSE Package
10-Lead Plastic MSOP, Exposed Die Pad
(Reference LTC DWG # 05-08-1664 Rev I)
BOTTOM VIEW OF
EXPOSED PAD OPTION
1.88
(.074)
1.88 ±0.102
(.074 ±.004)
0.889 ±0.127
(.035 ±.005)
1
0.29
REF
1.68
(.066)
0.05 REF
5.10
(.201)
MIN
1.68 ±0.102
3.20 – 3.45
DETAIL “B”
(.066 ±.004) (.126 – .136)
CORNER TAIL IS PART OF
THE LEADFRAME FEATURE.
FOR REFERENCE ONLY
DETAIL “B”
10
NO MEASUREMENT PURPOSE
0.50
(.0197)
BSC
0.305 ± 0.038
(.0120 ±.0015)
TYP
3.00 ±0.102
(.118 ±.004)
(NOTE 3)
0.497 ±0.076
(.0196 ±.003)
10 9
8
7 6
RECOMMENDED SOLDER PAD LAYOUT
REF
3.00 ±0.102
(.118 ±.004)
(NOTE 4)
4.90 ±0.152
(.193 ±.006)
DETAIL “A”
0.254
(.010)
0° – 6° TYP
1
2
3
4 5
GAUGE PLANE
0.53 ±0.152
(.021 ±.006)
0.86
(.034)
REF
1.10
(.043)
MAX
DETAIL “A”
0.18
(.007)
SEATING
PLANE
0.17 – 0.27
(.007 – .011)
TYP
0.1016 ±0.0508
(.004 ±.002)
0.50
(.0197)
BSC
MSOP (MSE) 0213 REV I
NOTE:
1. DIMENSIONS IN MILLIMETER/(INCH)
2. DRAWING NOT TO SCALE
3. DIMENSION DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS.
MOLD FLASH, PROTRUSIONS OR GATE BURRS SHALL NOT EXCEED 0.152mm (.006") PER SIDE
4. DIMENSION DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSIONS.
INTERLEAD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.152mm (.006") PER SIDE
5. LEAD COPLANARITY (BOTTOM OF LEADS AFTER FORMING) SHALL BE 0.102mm (.004") MAX
6. EXPOSED PAD DIMENSION DOES INCLUDE MOLD FLASH. MOLD FLASH ON E-PAD
SHALL NOT EXCEED 0.254mm (.010") PER SIDE.
4080Xfa
20
For more information www.linear.com/LTC4080X
LTC4080X
revision hisTory
REV
DATE
DESCRIPTION
PAGE NUMBER
A
07/15 Modified Typical Application diagrams
1, 22
4080Xfa
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no representa-
tion that the interconnection of its circuits as described herein will not infringe on existing patent rights.
21
LTC4080X
Typical applicaTion
Li-Ion Battery Charger with 1.5V Buck Regulator
Buck Efficiency vs Load Current
(VOUT = 1.5V)
500mA
100
80
60
40
20
0
1000
V
CC
V
BAT
EN_BUCK
SW
CC
4.2V
(3.75V
to 5.5V)
+
C
BAT
R4, 510Ω
R3, 510Ω
Li-Ion
EFFICIENCY
(Burst)
100
10
4.7µF
ACPR
BATTERY
L1, 1OµH*
EFFICIENCY
(PWM)
POWER
LOSS
LTC4080X
C
R1
PL
CHRG
(PWM)
10pF
715k
EN_CHRG
MODE
FB
V
OUT
1
POWER LOSS
(Burst)
(1.5V/300mA)
C
IN
GND
PROG
4.7µF
R
R2
806k
C
OUT
4.7µF
V
V
= 3.8V
= 1.5V
PROG
BAT
OUT
0.1
0.01
806Ω
L = 10µH
4080X TA02
C = 4.7mF
*COILCRAFT LPO1704-103M
0.01
0.1
1
10
100
1000
LOAD CURRENT (mA)
4080X G13
relaTeD parTs
PART NUMBER
Battery Chargers
LTC3550
DESCRIPTION
COMMENTS
Dual Input USB/AC Adapter Li-Ion Battery Charger Synchronous Buck Converter, Efficiency: 93%, Adjustable Output: 600mA,
with Adjustable Output 600mA Buck Converter
Charge Current: 950mA Programmable, USB Compatible, Automatic Input Power
Detection and Selection
LTC3550-1
Dual Input USB/AC Adapter Li-Ion Battery Charger Synchronous Buck Converter, Efficiency: 93%, Output: 1.875V at 600mA,
with 600mA Buck Converter
Charge Current: 950mA Programmable, USB Compatible, Automatic Input Power
Detection and Selection
LTC4054
Standalone Linear Li-Ion Battery Charger with
Integrated Pass Transistor in ThinSOTTM
Thermal Regulation Prevents Overheating, C/10 Termination
LTC4061
Standalone Li-Ion Charger with Thermistor
Interface
4.2V, 0.35% Float Voltage, Up to 1A Charge Current, 3mm × 3mm
DFN Package
LTC4061-4.4
LTC4062
Standalone Li-Ion Charger with Thermistor
Interface
4.4V (Max), 0.4% Float Voltage, Up to 1A Charge Current, 3mm × 3mm
DFN Package
Standalone Linear Li-Ion Battery Charger with
Micropower Comparator
Up to 1A Charge Current, Charges from USB Port, Thermal Regulation
3mm × 3mm DFN Package
LTC4063
LTC4080
Li-Ion Charger with Linear Regulator
Up to 1A Charge Current, 100mA, 125mV LDO, 3mm × 3mm DFN Package
Standalone 500mA Charger with 300mA
Synchronous Buck
For 1-Cell Li-Ion/Polymer Batteries; Trickle Charge; Timer Termination +C/10;
Thermal Regulation, Buck Output: 0.8V to V , Buck Input: 2.7V to 5.5V, 3mm ×
BAT
3mm DFN-10 Package
Power Management
LTC3405/
LTC3405A
300mA (I ), 1.5MHz, Synchronous Step-Down 95% Efficiency, V : 2.7V to 6V, V
= 0.8V, I = 20µA, I < 1µA,
OUT Q SD
OUT
IN
DC/DC Converter
ThinSOT Package
LTC3406/
LTC3406A
600mA (I ), 1.5MHz, Synchronous Step-Down 95% Efficiency, V : 2.5V to 5.5V, V
= 0.6V, I = 20µA, I < 1µA,
Q SD
OUT
IN
OUT
OUT
OUT
DC/DC Converter
ThinSOT Package
LTC3411
1.25A (I ), 4MHz, Synchronous Step-Down
95% Efficiency, V : 2.5V to 5.5V, V
= 0.8V, I = 60µA, I < 1µA,
Q SD
OUT
IN
DC/DC Converter
MS Package
LTC3440
600mA (I ), 2MHz, Synchronous Buck-Boost 95% Efficiency, V : 2.5V to 5.5V, V
= 2.5V, I = 25µA, I < 1µA,
Q SD
OUT
IN
DC/DC Converter
MS Package
LTC4411/LTC4412 Low Loss PowerPathTM Controller in ThinSOT
Automatic Switching Between DC Sources, Load Sharing, Replaces ORing Diodes
LTC4413
Dual Ideal Diode in DFN
2-Channel Ideal Diode ORing, Low Forward On-Resistance, Low Regulated
Forward Voltage, 2.5V ≤ V ≤ 5.5V
IN
ThinSOT and PowerPath are trademarks of Linear Technology Corporation.
4080Xfa
LT 0715 REV A • PRINTED IN USA
LinearTechnology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
22
●
●
LINEAR TECHNOLOGY CORPORATION 2007
(408)432-1900 FAX: (408) 434-0507 www.linear.com/LTC4080X
相关型号:
LTC4080XEMSE-PBF
500mA Standalone Li-Ion Charger with Integrated 300mA Synchronous Buck in 3mm × 3mm DFN
Linear
LTC4080XEMSE-TRPBF
500mA Standalone Li-Ion Charger with Integrated 300mA Synchronous Buck in 3mm × 3mm DFN
Linear
LTC4081EDD#PBF
LTC4081 - 500mA Li-Ion Charger with NTC Input and 300mA Synchronous Buck; Package: DFN; Pins: 10; Temperature Range: -40°C to 85°C
Linear
LTC4081EDD#TRPBF
LTC4081 - 500mA Li-Ion Charger with NTC Input and 300mA Synchronous Buck; Package: DFN; Pins: 10; Temperature Range: -40°C to 85°C
Linear
©2020 ICPDF网 联系我们和版权申明