ZXLD1370QESTTC [DIODES]
AUTOMOTIVE COMPLIANT 60V HIGH ACCURACY BUCK/;
| 型号： | ZXLD1370QESTTC |
| 厂家： | 
DIODES INCORPORATED |
| 描述： | AUTOMOTIVE COMPLIANT 60V HIGH ACCURACY BUCK/ |
| 文件： | 总39页 (文件大小：1372K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
ZXLD1370Q
AUTOMOTIVE COMPLIANT 60V HIGH ACCURACY BUCK/
BOOST/BUCK-BOOST LED DRIVER-CONTROLLER
Description
Pin Assignments
The ZXLD1370Q is an LED driver controller IC for driving external
MOSFETs to drive high-current LEDs. It is a multi-topology controller
that efficiently controls the current through series connected LEDs.
The multi-topology enables it to operate in buck, boost and buck-
boost configurations.
(Top View)
The 60V capability coupled with its multi-topology capability enables it
to be used in a wide range of applications and drive in excess of
15 LEDs in series.
The ZXLD1370Q is a modified hysteretic controller using a patent
pending control scheme providing high output current accuracy in all
three modes of operation. High accuracy dimming is achieved
through DC control and high frequency PWM control.
TSSOP-16EP
The ZXLD1370Q uses two pins for fault diagnosis. A flag output
highlights a fault, while the multilevel status pin gives further
information on the exact fault.
Features
0.5% Typical Output Current Accuracy
6V to 60V Operating Voltage Range
LED Driver Supports Buck, Boost and Buck-Boost Configurations
Wide Dynamic Range Dimming
20:1 DC Dimming
1000:1 Dimming Range at 500Hz
The ZXLD1370Q is qualified to AEC-Q100 Grade 1 and is automotive
compliant supporting PPAP documents.
Up to 1MHz Switching
High Temperature Control of LED Current Using TADJ
Available in Thermally Enhanced TSSOP-16EP Package with
Green Molding Compound
Totally Lead-Free & Fully RoHS Compliant (Notes 1 & 2)
Halogen and Antimony Free. “Green” Device (Note 3)
Automotive Compliant
Qualified to AEC-Q100 Grade 1 and TS16949 Certification
PPAP Capable (Note 4)
Notes:
1. No purposely added lead. Fully EU Directive 2002/95/EC (RoHS), 2011/65/EU (RoHS 2) & 2015/863/EU (RoHS 3) compliant.
2. See https://www.diodes.com/quality/lead-free/ for more information about Diodes Incorporated’s definitions of Halogen- and Antimony-free, "Green" and
Lead-free.
3. Halogen- and Antimony-free "Green” products are defined as those which contain <900ppm bromine, <900ppm chlorine (<1500ppm total Br + Cl) and
<1000ppm antimony compounds.
4. Automotive products are AEC-Q101 qualified and are PPAP capable. Refer to https://www.diodes.com/quality/.
Typical Applications Circuit
VIN 8V
to 18V
I LED = 1A
R1
0R1
LED 1
to 4
L1
33mH
VAUX
VIN
ISM
C1
PWM
GI
4.7µF
SD1
PSD3100
COUT
ADJ
REF
TADJ
GATE
4.7µF
Q1
DMN6068LK3
RGI2
62k
FLAG
R4
2k
STATUS
SGND PGND
RGI1
51k
SHP
U1
ZXLD1370Q
C2
100pF
TH1
10k
GND
Thermally connected
Buck-Boost Diagram Utilizing Thermistor and TADJ
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© Diodes Incorporated
ZXLD1370Q
Document number: DS37117 Rev. 4 - 2
ZXLD1370Q
Pin Descriptions
Type
Pin Name
Pin
Function
(Note 5)
Adjust Input (for DC Output Current Control)
Connect to REF to set 100% output current.
ADJ
1
I
Drive with DC voltage (125mV<VADJ< 2.5V) to adjust output current from 10% to 200% of set value.
The ADJ pin has an internal clamp that limits the internal node to less than 3V. This provides some
failsafe should they get overdriven.
REF
2
3
O
I
Internal 1.25V Reference Voltage Output
Temperature Adjust Input for LED Thermal Current Control
Connect thermistor/resistor network to this pin to reduce output current above a preset temperature
threshold.
TADJ
Connect to REF to disable thermal compensation function (see section on Thermal Control).
Shaping Capacitor for Feedback Control Loop
Connect 100pF 20% capacitor from this pin to ground to provide loop compensation.
SHP
4
5
I/O
O
Operation Status Output (Analog Output)
Pin is at 4.5V (nominal) during normal operation.
Pin switches to a lower voltage to indicate specific operation warnings or fault conditions.(see section
on STATUS output).
STATUS
Status pin voltage is low during shutdown mode.
SGND
PGND
6
7
P
P
Signal Ground - Connect to 0V
Power Ground - Connect to 0V and pin 8 to maximize copper area.
Not Connected Internally – recommend connection to pin 7 (PGND), to maximize PCB copper for
thermal dissipation.
N/C
8
—
Not Connected Internally – recommend connection pin 10 (GATE) to permit wide copper trace to gate
of MOSFET.
N/C
9
—
GATE
10
O
Gate drive output to external NMOS transistor – connect to pin 9
Auxiliary Positive Supply to Internal Switch Gate Driver
Connect to VIN, or auxiliary supply from 6V to 15V supply to reduce internal power dissipation (refer to
Application Section for more details).
VAUX
11
P
Decouple to ground with capacitor close to device (refer to Applications section).
Input Supply to Device (6V to 60V)
VIN
ISM
12
13
P
I
Decouple to ground with capacitor close to device (refer to Applications section).
Current Monitor Input
Connect current sense resistor between this pin and VIN.
The nominal voltage across the resistor is 225mV.
Flag Open Drain Output
FLAG
PWM
14
15
O
I
Pin is high impedance during normal operation.
Pin switches low to indicate a fault, or warning condition.
Digital PWM Output Current Control
Pin is driven either by open drain or push-pull, 3.3V or 5V logic levels.
Drive with frequency higher than 100Hz to gate output ‘on’ and ‘off’ during dimming control.
The device enters standby mode when PWM pin is driven with logic low level for more than 15ms
nominal (refer to Application Section for more details).
Gain Setting Input
Used to set the device in Buck, Boost or Buck-Boost modes.
Connect to ADJ in Buck mode operation.
GI
16
I
For Boost and Buck-Boost modes, connect to resistive divider from ADJ to SGND. This defines the ratio
of switch current to LED current (see Application Section). The GI pin has an internal clamp that limits
the internal node to less than 3V. This provides some failsafe should they get overdriven.
EP
PAD
P
Exposed Paddle - Connect to 0V plane for electrical and thermal management.
Note:
5. Type refers to whether or not pin is an Input, Output, Input/Output or power supply pin.
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© Diodes Incorporated
ZXLD1370Q
Document number: DS37117 Rev. 4 - 2
ZXLD1370Q
Functional Block Diagram
D
L
LOAD
RS
VIN
VAUX
VIN
ISM
FLAG
STATUS
TADJ
Error
report
Fast
current
monitor
Accurate
current
monitor
Error amp
-
REF
Reference
Demand
current
source
R1
GI
Frequency &
hysteresis
control
R2
VAUX
ADJ
+
-
COMPIN
Gate
driver
PWM
SGND
PGND
Absolute Maximum Ratings (Note 6) (Voltages to GND, unless otherwise specified.)
Symbol
VIN
Parameter
Rating
Unit
V
Input Supply Voltage Relative to GND
Auxiliary Supply Voltage Relative to GND
Current Monitor Input Relative to GND
Current Monitor Sense Voltage (VIN-VISM
Gate Driver Output Voltage
-0.3 to +65
-0.3 to +65
-0.3 to +65
-0.3 to +5
-0.3 to +20
18
V
VAUX
V
VISM
V
VSENSE
VGATE
IGATE
VFLAG
)
V
Gate Driver Continuous Output Current
Flag Output Voltage
mA
V
-0.3 to 40
VPWM, VADJ
,
Other Input Pins
-0.3 to +5.5
V
VTADJ, VGI
Maximum Junction Temperature
Storage Temperature
+150
° C
° C
TJ
-55 to +150
TST
Note:
6. For correct operation, SGND and PGND should always be connected together.
Caution:
Stresses greater than the 'Absolute Maximum Ratings' specified above, may cause permanent damage to the device. These are stress ratings only;
functional operation of the device at conditions between maximum recommended operating conditions and absolute maximum ratings is not implied.
Device reliability may be affected by exposure to absolute maximum rating conditions for extended periods of time.
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ZXLD1370Q
Document number: DS37117 Rev. 4 - 2
ZXLD1370Q
ESD Susceptibility
ESD Susceptibility
Human Body Model
Charged Device Model
Rating
1,500
1,000
Unit
V
HBM
CDM
V
Caution:
Semiconductor devices are ESD sensitive and may be damaged by exposure to ESD events. Suitable ESD precautions should be taken when handling
and transporting these devices.
Package Thermal Data
Thermal Resistance
Package
Typical
50
Unit
°C/W
°C/W
TSSOP-16EP
TSSOP-16EP
Junction-to-Ambient, JA (Note 7)
Junction-to-Case, JC
23
Note: 7. Measured on High Effective Thermal Conductivity Test Board" according JESD51.
Recommended Operating Conditions
Symbol
Parameter
Performance/Comment
Normal Operation
Min
Max
Unit
8
Input Supply Voltage Range
60
V
V
VIN
Reduced Performance Operation
(Note 8)
6.3
8
Normal Operation
Auxiliary Supply Voltage Range (Note 9)
60
VAUX
Reduced Performance Operation
(Note 8)
6.3
Current Sense Monitor Input Range
Differential Input Voltage
—
6.3
0
60
V
VISM
450
mV
VSENSE
VVIN-VISM, with 0 ≤ VADJ ≤ 2.5V
External DC Control Voltage Applied to ADJ Pin to
Adjust Output Current
DC Brightness Control Mode from
10% to 200%
0.125
—
2.5
1
V
VADJ
IREF
Reference External Load Current
REF Sourcing Current
mA
kHz
Recommended Switching Frequency Range
(Note 10)
—
300
1,000
fMAX
—
To Achieve 1000:1 Resolution
To Achieve 500:1 Resolution
PWM Input High or Low
—
0
100
100
0.002
2
V
Hz
Hz
ms
V
VTADJ
Temperature Adjustment (TADJ) Input Voltage Range
VREF
500
1,000
10
Recommended PWM Dimming Frequency Range
fPWM
PWM Pulse Width in Dimming Mode
PWM Pin High-Level Input Voltage
PWM Pin Low-Level Input Voltage
Junction Temperature Range
tPWMH/L
VPWMH
VPWML
TJ
5.5
—
0
0.4
V
—
—
-40
-40
0.20
+125
+125
0.50
° C
° C
—
Ambient Temperature Range
TA
GI
Gain Setting Ratio for Boost and Buck-Boost Modes
Ratio = VGI/VADJ
Notes:
8. Device starts up above 6V and as such the minimum applied supply voltage has to be above 6.5V (plus any noise margin). The ZXLD1370Q will,
however, continue to function when the input voltage is reduced from ≥ 8V down to 6.3V. When operating with input voltages below 8V, the output
current and device parameters may deviate from their normal values; and is dependent on power MOSFET switch, load and ambient temperature
conditions. To ensure best operation in Boost and Buck-Boost modes with input voltages, VIN, between 6.3 and 8V a suitable boot-strap network on
VAUX pin is recommended. Performance in Buck mode will be reduced at input voltages (VIN, VAUX) below 8V. – a boot-strap network cannot be
implemented in buck mode and so a suitable low VT MOSFET should be selected.
9. VAUX can be driven from a voltage higher than VIN to provide higher efficiency at low VIN voltages, but to avoid false operation; a voltage should not be
applied to VAUX in the absence of a voltage at VIN
.
10. The device contains circuitry to control the switching frequency to approximately 400kHz. The maximum and minimum operating frequency is not tested
in production.
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© Diodes Incorporated
ZXLD1370Q
Document number: DS37117 Rev. 4 - 2
ZXLD1370Q
Electrical Characteristics (VIN = VAUX =12V, TA = +25°C, unless otherwise specified.)
Symbol
Supply and Reference Parameters
Undervoltage Detection Threshold
Parameter
Conditions
Min
Typ
Max
Unit
5.2
5.5
5.6
6.0
6.3
6.5
V
V
VUV-
VIN or VAUX Falling
Normal Operation to Switch Disabled
Undervoltage Detection Threshold
Switch Disabled to Normal Operation
VUV+
VIN or VAUX Rising
—
—
—
—
1.5
150
90
3.0
300
150
10.0
mA
µ A
µ A
µ A
V
IQ-IN
IQ-AUX
ISB-IN
Quiescent Current into VIN
Quiescent Current into VAUX
Standby Current into VIN
Standby Current into VAUX
Internal Reference Voltage
PWM Pin Floating
Output not Switching
PWM Pin Grounded
for more than 15ms
0.7
ISB-AUX
VREF
No Load
1.237
-5
1.250
—
1.263
—
Sourcing 1mA
Change in Reference Voltage with Output
Current
mV
VREF
Sinking 100µ A
—
—
5
—
Reference Voltage Line Regulation
Reference Temperature Coefficient
-60
—
-90
dB
VREF_LINE
VREF-TC
VIN = VAUX, 6.5V < VIN = < 60V
—
—
+/-50
ppm/° C
DC-DC Converter Parameters
DC Brightness Control Mode
10% to 200%
External DC Control Voltage Applied to ADJ Pin
0.125
—
1.25
—
2.50
V
VADJ
IADJ
VGI
IGI
to Adjust Output Current (Note 11)
ADJ Input Current (Note 11)
VADJ ≤ 2.5V
100
5
nA
µ A
VADJ = 5.0V
GI Voltage Threshold for Boost and Buck-boost
Modes Selection (Note 11)
—
—
0.8
V
VADJ = 1.25V
VGI ≤ 2.5V
100
5
nA
µ A
GI Input Current (Note 11)
—
—
VGI = 5.0V
PWM Input Current
—
36
15
100
25
µA
ms
IPWM
VPWM = 5.5V
PWM Pulse Width (to enter shutdown state)
PWM Input Low
10
tPWMOFF
Thermal Shutdown Upper Threshold
(GATE Output Forced Low)
Temperature Rising
Temperature Falling
—
—
+150
+125
—
—
°C
°C
TSDH
TSDL
Thermal Shutdown Lower Threshold
(GATE Output Re-enabled)
High-Side Current Monitor (Pin ISM)
Input Current
—
—
11
20
µA
IISM
@ VISM = 12V
Buck
218
—
Current Measurement Sense Voltage
Boost (Note 12)
mV
VSENSE
VADJ = 1.25V
—
225
—
Buck-Boost (Note 12)
—
0.25
350
2
%
VSENSE_ACC Accuracy of Nominal VSENSE Threshold Voltage
VADJ = 1.25V
Overcurrent Sense Threshold Voltage
300
375
mV
VSENSE-OC
Notes: 11. The ADJ and GI pins have an internal clamp that limits the internal node to less than 3V. This provides some failsafe should those pins get overdriven.
12. Initial sense voltage in Boost and Buck-Boost modes at maximum duty cycle.
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ZXLD1370Q
Document number: DS37117 Rev. 4 - 2
ZXLD1370Q
Electrical Characteristics (Cont.) (VIN = VAUX =12V, TA = +25°C, unless otherwise specified.)
Symbol
Parameter
Conditions
Min
Typ
Max
Unit
Output Parameters
—
—
—
—
FLAG Pin Low Level Output Voltage
FLAG Pin Open Drain Leakage Current
Output Sinking 1mA
0.5
1
V
VFLAGL
µ A
IFLAGOFF
VFLAG = 40V
Normal Operation
4.2
4.5
4.8
Out of Regulation (VSHP out of range)
(Note 14)
3.3
3.6
3.9
3.3
3.3
1.5
3.6
3.6
1.8
3.9
3.9
2.1
VIN Undervoltage (VIN < 5.6V)
STATUS Flag No-Load Output Voltage
(Note 13)
V
VSTATUS
Switch Stalled (tON or tOFF > 100µs)
Overtemperature (TJ > +125°C)
Excess Sense Resistor Current
(VSENSE > 0.32V)
0.6
0.9
10
1.2
Output Impedance of STATUS Output
Normal Operation
—
—
kΩ
RSTATUS
Driver Output (PIN GATE)
No Load Sourcing 1mA
VIN = VAUX = 12V
(Note 15)
High Level Output Voltage
9.5
10.5
12
V
V
VGATEH
VGATEL
—
—
Low Level Output Voltage
Sinking 1mA (Note 16)
0.5
VIN = VAUX = VISM = 18V
IGATE = 1mA
High Level GATE CLAMP Voltage
—
12.8
15.0
V
VGATECL
Charging or discharging gate of external
switch with QG = 10nC and 400kHz
Dynamic Peak Current Available during Rise
or Fall of Output Voltage
—
—
300
100
—
mA
µ s
IGATE
Time to assert ‘STALL’ Flag and Warning on
STATUS Output (Note 17)
GATE Low or High
170
tSTALL
LED Thermal Control Circuit (TADJ) Parameters
Onset of Output Current Reduction
(VTADJ Falling)
Upper Threshold Voltage
560
625
690
mV
VTADJH
Output Current Reduced to <10% of Set
Value (VTADJ Falling)
Lower Threshold Voltage
TADJ Pin Input Current
380
440
500
1
mV
µA
VTADJL
ITADJ
—
—
VTADJ = 1.25V
Notes:
13. In the event of more than one fault/warning condition occurring, the higher priority condition will take precedence. E.g. ‘Excessive coil current’ and
‘Out of regulation’ occurring together will produce an output of 0.9V on the STATUS pin. The voltage levels on the STATUS output assume the
Internal regulator to be in regulation and V
minimum value of 6V.
<=V
ADJ
. A reduction of the voltage on the STATUS pin will occur when the voltage on V is near the
IN
REF
14. Flag is asserted if V
<2.5V or V
SHP
>3.5V.
SHP
15. GATE is switched to the supply voltage V
for low values of V
(i.e. between 6V and approximately 12V). For V
AUX
>12V, GATE is clamped
AUX
AUX
internally to prevent it exceeding 15V. Below 12V the minimum GATE pin voltage will be 2.5V below V
16. GATE is switched to PGND by an NMOS transistor.
.
AUX
17. If t
ON
exceeds tSTALL, the device will force GATE low to turn off the external switch and then initiate a restart cycle. During this phase, ADJ is
grounded internally and the SHP pin is switched to its nominal operating voltage, before operation is allowed to resume. Restart cycles will be
repeated automatically until the operating conditions are such that normal operation can be sustained. If tOFF exceeds tSTALL, the switch will remain off
until normal operation is possible.
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ZXLD1370Q
Document number: DS37117 Rev. 4 - 2
ZXLD1370Q
Typical Characteristics
3
1.252
1.2515
2.5
2
1.251
1.2505
1.25
1.5
1
1.2495
1.249
0.5
0
1.2485
1.248
6
12 18 24
SUPPLY VOLTAGE (V)
Figure 1 Supply Current vs. Supply Voltage
30 36 42 48 54 60
-40 -25 -10
5
20 35 50 65 80 95 110 125
JUNCTION TEMPERATURE
Figure 2 VREF vs. Temperature
(° C )
1500
1250
100%
80%
60%
40%
1000
750
500
250
20%
0%
0
0
0
250
500
750
1000
1250
10 20 30 40 50 60 70 80 90 100
PWM DUTY CYCLE (%)
TADJ PIN VOLTAGE (mV)
Figure 4 ILED vs. PWM Duty Cycle
Figure 3 LED Current vs. TADJ Voltage
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ZXLD1370Q
Document number: DS37117 Rev. 4 - 2
ZXLD1370Q
Typical Characteristics (Cont.)
900
750
1400
1200
1500
700
650
600
550
500
450
400
1250
1000
750
1000
800
600
450
I
LED
350
Switching
Frequency
600
300
250
200
500
300
150
0
400
T
A = 25° C
A
150
100
50
V
= V = 24V
IN
AUX
250
0
8LEDs
L = 33µH
GI = 0.23
200
R
= 300m
S
0
0
0
0.5
1
1.5
2
2.5
0
0.5
1.5
ADJ VOLTAGE (V)
2.5
1
2
(V)
ADJ VOLTAGE
Figure 5 Buck LED Current, Switching Frequency vs. VADJ
Figure 6 Buck-Boost LED Current, Switching Frequency vs. VADJ
700
100%
700
650
T
= 25C
A
90%
80%
70%
60%
50%
40%
30%
20%
L
=
3
3
µH
600
550
500
450
400
350
300
600
500
400
R
= 150m
S
Buck Mode
2 LEDS
I
LED
Switching
Frequency
300
200
100
0
250
200
150
100
TA
= 25° C
V
= V = 12V
IN
AUX
12 LEDs
L = 33µH
= 300m
10%
0%
R
S
50
0
6
12 18 24 30 36 42 48 54 60
INPUT VOLTAGE (V)
0
0.25 0.5 0.75
1
1.25 1.5 1.75 2 2.25 2.5
(V)
ADJ VOLTAGE
Figure 7 Boost LED Current, Switching Frequency vs. VADJ
Figure 8 Duty Cycle vs. Input Voltage
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ZXLD1370Q
Document number: DS37117 Rev. 4 - 2
ZXLD1370Q
Typical Characteristics (Cont.) Buck Mode – RS = 150mΩ, L = 33µH
1.500
7 LEDs
9 LEDs
5 LEDs
11 LEDs
13 LEDs
1 LED
3 LEDs
15 LEDs
1.490
1.480
1.470
T
= 25°C
A
V
= V
IN
AUX
1.460
1.450
1.440
1.430
6.5
11
15.5
20
24.5
29
33.5
38
42.5
47
51.5
56
60.5
INPUT VOLTAGE (V)
Figure 9 Load Current vs. Input Voltage & Number of LED
1000
1 LED
3 LEDs
5 LEDs
7 LEDs
9 LEDs
11 LEDs
13 LEDs
15 LEDs
900
800
TA = 25° C
V
= V
IN
AUX
700
600
500
400
300
200
100
0
6.5
11
15.5
20
24.5
29
INPUT VOLTAGE (V)
Figure 10 Frequency vs. Input Voltage & Number of LED
33.5
38
42.5
47
51.5
56
60.5
100
95
90
85
80
75
TAA = 25° C
V
= V
IN
AUX
70
65
60
6.5
11
15.5
20
24.5
29
33.5
38
42.5
47
51.5
56
60.5
INPUT VOLTAGE (V)
Figure 11 Efficiency vs. Input & Number of LED
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ZXLD1370Q
Document number: DS37117 Rev. 4 - 2
ZXLD1370Q
Typical Characteristics (Cont.) Buck Mode – RS = 300mΩ, L = 47µH
0.740
0.735
0.730
0.725
0.720
TA = 25° C
V
= V
IN
AUX
2 LEDs
3 LEDs
5 LEDs
7 LEDs
9 LEDs
11 LEDs
13 LEDs
15 LEDs
0.715
6.5
11
15.5
20
24.5
29
33.5
38
42.5
47
51.5
56
60.5
INPUT VOLTAGE (V)
Figure 12 ILED vs. Input & Number of LED
1000
900
800
700
600
500
400
300
200
2 LEDs
3 LEDs
5 LEDs
7 LEDs
9 LEDs
11 LEDs
13 LEDs
15 LEDs
TA = 25° C
V
= V
IN
AUX
100
0
6.5
11
15.5
20
24.5
29
33.5
38
42.5
47
51.5
56
60.5
INPUT VOLTAGE (V)
Figure 13 Frequency ZXLD1370Q – Buck Mode – L47µH
100
95
90
85
80
75
TA = 25° C
V
= V
IN
AUX
70
65
60
2 LEDs
3 LEDs
5 LEDs
7 LEDs
9 LEDs
11 LEDs
13 LEDs
15 LEDs
6.5
11
15.5
20
24.5
29
33.5
38
42.5
47
51.5
56 60.5
INPUT VOLTAGE (V)
Figure 14 Efficiency vs. Input Voltage & Number of LED
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Typical Characteristics (Cont.) Boost Mode – RS = 150mΩ, GIRATIO = 0.23, L = 33µH
0.400
0.350
0.300
TA = 25° C
A
V
= V
IN
AUX
0.250
0.200
0.150
0.100
0.050
3 LEDs
4 LEDs
6 LEDs
8 LEDs
10 LEDs
12 LEDs
14 LEDs
16 LEDs
0.000
6.5
10
13.5
17
20.5
24
27.5
31
34.5
38
41.5
45
48.5
INPUT VOLTAGE (V)
Figure 15 ILED vs. Input Voltage & Number of LED
500
450
3 LEDs
4 LEDs
6 LEDs
8 LEDs
10 LEDs
12 LEDs
14 LEDs
16 LEDs
TA = 25° C
400
V
= V
IN
AUX
350
300
250
200
150
100
50
Boosted voltage across
LEDs approaching VIN
6.5
10
13.5
20.5
24
INPUT VOLTAGE (V)
Figure 16 Frequency vs. Input Voltage & Number of LED
27.5
31
34.5
38
41.5
45 48.5
17
100
95
6 LEDs
8 LEDs
10 LEDs
4 LEDs
12 LEDs
14 LEDs
16 LEDs
3 LEDs
90
85
80
75
70
TA = 25° C
V
= V
IN
AUX
65
60
20.5
6.5
10
13.5
17
24
27.5
31
34.5
38
41.5
45
48.5
INPUT VOLTAGE (V)
Figure 17 Efficiency vs. Input Voltage & Number of LED
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Typical Characteristics (Cont.) Buck-Boost Mode – RS = 150mΩ, GIRATIO = 0.23, L = 47µH
0.370
3 LEDs
4 LEDs
5 LEDs
6 LEDs
7 LEDs
8 LEDs
0.365
0.360
0.355
0.350
0.345
0.340
0.335
0.330
6.5
8
9.5
11
12.5
14
15.5
17
INPUT VOLTAGE (V)
Figure 18 LED Current vs. Input Voltage & Number of LED
800
700
3 LEDs
4 LEDs
5 LEDs
6 LEDs
7 LEDs
8 LEDs
600
500
400
300
200
100
0
6.5
8
9.5
11
12.5
14
15.5
17
INPUT VOLTAGE (V)
Figure 19 Switching Frequency vs. Input Voltage & Number of LED
100
95
3 LEDs
4 LEDs
5 LEDs
6 LEDs
7 LEDs
8 LEDs
90
85
80
75
70
65
60
6.5
8
9.5
11
12.5
14
15.5
17
INPUT VOLTAGE (V)
Figure 20 Efficiency vs. Input Voltage & Number of LED
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Application Information
The ZXLD1370Q is a high-accuracy hysteretic inductive buck/boost/buck-boost controller designed to be used with an external NMOS switch for
current-driving single or multiple series-connected LEDs. The device can be configured to operate in buck, boost, or buck-boost modes by suitable
configuration of the external components as shown in the schematics shown in the device operation description.
Device Description
a) Buck Mode – the most simple buck circuit shown in Figure 21
Control of the LED current buck mode is achieved by sensing the coil
current in the sense resistor RS, connected between the two inputs of a
current monitor within the control loop block. An output from the control
loop drives the input of a comparator which drives the gate of the
external NMOS switch transistor Q1 via the internal Gate Driver. When
the switch is on, the drain voltage of Q1 is near zero. Current flows
from VIN, via RS, LED, coil and switch to ground. The current ramps up
until an upper threshold value is reached (see Figure 22). At this point,
GATE goes low, the switch is turned off and the drain voltage increases
to VIN plus the forward voltage, VF, of the Schottky diode D1. Current
ZXLD1370Q
flows via RS, LED, coil and D1 back to VIN. When the coil current has
ramped down to a lower threshold value, GATE goes high, the switch is
turned on again and the cycle of events repeats, resulting in continuous
oscillation. The feedback loop adjusts the NMOS switch duty cycle to
stabilize the LED current in response to changes in external conditions,
including input voltage and load voltage.
Figure 21 Buck Configuration
The average current in the sense resistor, LED and coil is equal to the
average of the maximum and minimum threshold currents. The ripple
current (hysteresis) is equal to the difference between the thresholds.
The control loop maintains the average LED current at the set level by
adjusting the switch duty cycle continuously to force the average sense
resistor current to the value demanded by the voltage on the ADJ pin.
This minimizes variation in output current with changes in operating
conditions.
The control loop also regulates the switching frequency by varying the
level of hysteresis. The hysteresis has a defined minimum (typ 5%) and
a maximum (typ 30%). The frequency may deviate from nominal in
some conditions. This depends upon the desired LED current, the coil
inductance and the voltages at the input and the load. Loop
compensation is achieved by a single external capacitor C2, connected
between SHP and SGND.
The control loop sets the duty cycle so that the sense voltage is:
VADJ
VREF
0.218
VSENSE
Therefore,
0.218
RS
VADJ
VREF
(Buck mode) Equation 1
ILED
If the ADJ pin connected to the REF pin, this simplifies to:
0.218
RS
VADJ
VREF
(Buck mode)
ILED
Figure 22 Operating Waveforms (Buck Mode)
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Application Information (Cont.)
b) Boost and Buck-Boost Modes – the most simple boost/buck-boost circuit shown in Figure 23
Connect cathode of LED(s) to VIN for buck-boost mode or GND for boost mode
Control in Boost and Buck-boost mode is achieved by sensing the coil
current in the series resistor RS, connected between the two inputs of a
current monitor within the control loop block. An output from the control loop
drives the input of a comparator which drives the gate of the external NMOS
switch transistor Q1 via the internal Gate Driver. When the switch is on, the
drain voltage of Q1 is near zero. Current flows from VIN, via RS, coil and
switch to ground. The current ramps up until an upper threshold value is
reached (see Figure 24). At this point, GATE goes low, the switch is turned
off and the drain voltage increases to either:
1) the load voltage VLEDS plus the forward voltage of D1 in Boost
ZXLD1370Q
configuration,
or
2) the load voltage VLEDS plus the forward voltage of D1 plus VIN in
Buck-boost configuration.
Current flows via RS, coil, D1 and LED back to VIN (Buck-boost mode), or
GND (Boost mode). When the coil current has ramped down to a lower
threshold value, GATE goes high, the switch is turned on again and the
cycle of events repeats, resulting in continuous oscillation. The feedback
loop adjusts the NMOS switch duty cycle to stabilize the LED current in
response to changes in external conditions, including input voltage and load
voltage. Loop compensation is achieved by a single external capacitor C2,
connected between SHP and SGND. Note that in reality, a load capacitor
COUT is used, so that the LED current waveform shown is smoothed.
Figure 23 Boost and Buck-Boost Configuration
The average current in the sense resistor and coil, IRS, is equal to the
average of the maximum and minimum threshold currents and the ripple
current (hysteresis) is equal to the difference between the thresholds.
The average current in the LED, ILED, is always less than IRS. The feedback
control loop adjusts the switch duty cycle, D, to achieve a set point at the
sense resistor. This controls IRS. During the interval tOFF, the coil current
flows through D1 and the LED load. During tON, the coil current flows
through Q1, not the LEDs. Therefore the set point is modified by D using a
gating function to control ILED indirectly. In order to compensate internally for
the effect of the gating function, a control factor, GI_ADJ is used. GI_ADJ is
set by a pair of external resistors, RGI1 and RGI2 (see Figure 23). This allows
the sense voltage to be adjusted to an optimum level for power efficiency
without significant error in the LED controlled current.
RGI1
GI_ ADJ
RGI1 RGI2
Equation 2 (Boost and Buck-Boost modes)
The control loop sets the duty cycle so that the sense resistor current is:
0.225 GI_ ADJ
VADJ
VREF
RS
1 D
RS
Equation 3 (Boost and Buck-Boost modes)
Figure 24 Operating Waveforms
(Boost and Buck-Boost modes)
IRS equals the coil current. The coil is connected only to the switch and the
Schottky diode. The Schottky diode passes the LED current.
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Application Information (Cont.)
Therefore the average LED current is the coil current multiplied by the Schottky diode duty cycle, 1-D.
0.225
RS
VADJ
VREF
ILED IRS
1D
GI_ ADJ
(Boost and Buck-boost)
Equation 4
This shows that the LED current depends on the ADJ pin voltage, the reference voltage and 3 resistor values (RS, RGI1 and RGI2). It is
independent of the input and output voltages.
If the ADJ pin is connected to the REF pin, this simplifies to
0.225
RS
GI_ ADJ
(Boost and Buck-boost)
ILED
Now ILED is dependent only on the 3 resistor values.
Considering power dissipation and accuracy, it is useful to know how the mean sense voltage varies with input voltage and other parameters.
GI_ ADJ
VADJ
VREF
VRS IRS
0.225
(Boost and Buck-boost)
Equation 5
1D
This shows that the sense voltage varies with duty cycle in Boost and Buck-Boost configurations.
Application Circuit Design
External component selection is driven by the characteristics of the load and the input supply, since this will determine the kind of topology being
used for the system. Component selection begins with the current setting procedure, the inductor/frequency setting and the MOSFET selection.
Finally, after selecting the freewheeling diode and the output capacitor (if needed), the application section will cover the PWM dimming and
thermal feedback. The full procedure is greatly accelerated by the web Calculator spreadsheet, which includes fully automated component
selection, and is available on the Diodes Incorporated web site. However, the full calculation is also given here.
Some components depend upon the switching frequency and the duty cycle. The switching frequency is regulated by the ZXLD1370Q to a large
extent, depending upon conditions. This is discussed in a later paragraph dealing with coil selection.
Duty Cycle Calculation and Topology Selection
The duty cycle is a function of the input and output voltages. Approximately, the MOSFET switching duty cycle is
VOUT
for Buck
DBUCK
VIN
VOUT VIN
for Boost
Equation 6
DBOOST
VOUT
VOUT
VOUT VIN
for Buck-Boost
DBB
Because D must always be a positive number less than 1, these equations show that:
VOUT < VIN
for Buck (voltage step-down)
VOUT > VIN
for Boost (voltage step-up)
VOUT > or = or < VIN
for Buck-Boost (voltage step-down or step-up)
This allows us to select the topology for the required voltage range.
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Application Information (Cont.)
More exact equations are used in the web Calculator. These are:
VOUT VF IOUT RS RCOIL
for Buck
DBUCK
VIN VF VDSON
VOUT VIN
IIN RS RCOIL VF
for Boost
Equation 7
DBOOST
VOUT VF VDSON
VOUT VF
I
IN
IOUT RS RCOIL
for Buck-Boost
DBB
VOUT VIN VF VDSON
Where
VF
VDSON
RCOIL
= Schottky diode forward voltage, estimated for the expected coil current, ICOIL
= MOSFET drain source voltage in the ON condition (dependent on RDSON and drain current = ICOIL
= DC winding resistance of L1
)
The additional terms are relatively small, so the exact equations will only make a significant difference at lower operating voltages at the input
and output, i.e. low input voltage or a small number of LEDs connected in series. The estimates of VF and VDSON depend on the coil current. The
mean coil current, ICOIL depends upon the topology and upon the mean terminal currents as follows:
ILED
for Buck
ICOIL
=
IIN
for Boost
Equation 8
IIN + ILED
for Buck-Boost
ILED is the target LED current and is already known. IIN will be calculated with some accuracy later, but can be estimated now from the electrical
power efficiency. If the expected efficiency is roughly 90%, the output power POUT is 90% of the input power, PIN, and the coil current is
estimated as follows.
POUT
ILED N VLED ≈ 0.9 IIN VIN
where N is the number of LEDs connected in series, and VLED is the forward voltage drop of a single LED at ILED
≈ 0.9 PIN
or
.
N
ILED VLED
0.9
So
IN
I
Equation 9
VIN
Equation 9 can now be used to find ICOIL in Equation 8, which can then be used to estimate the small terms in Equation 7. This completes the
calculation of Duty Cycle and the selection of Buck, Boost or Buck-Boost topology.
An initial estimate of duty cycle is required before we can choose a coil. In Equation 7, the following approximations are recommended:
VF
= 0.5V
= 0.5V
= 0.5V
= 0.1V
= 1.1V
IIN(RS+RCOIL
)
IOUT(RS+RCOIL
VDSON
)
(IIN+IOUT)(RS+RCOIL
)
Then Equation 7 becomes:
1
VOUT
for Buck
DBUCK
0.4
VIN
VOUT VIN
1
0.4
for Boost
Equation 7a
DBOOST
VOUT
1.6
VOUT
VOUT VIN
for Buck-Boost
DBB
0.4
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Application Information (Cont.)
Setting the LED current
The LED current requirement determines the choice of the sense resistor RS. This also depends on the voltage on the ADJ pin and the voltage on
the GI pin, according to the topology required.
The ADJ pin may be connected directly to the internal 1.25V reference (VREF) to define the nominal 100% LED current. The ADJ pin can also be
driven with an external DC voltage between 125mV and 2.5V to adjust the LED current proportionally between 10% and 200% of the nominal
value.
For a divider ratio GI_ADJ greater than 0.65V, the ZXLD1370Q operates in Buck mode when VADJ = 1.25V. If GI_ADJ is less than 0.65V (typical),
the device operates in Boost or Buck-Boost mode, according to the load connection. This 0.65V threshold varies in proportion to VADJ, i.e., the
Buck mode threshold voltage is 0.65 VADJ /1.25V.
ADJ and GI are high impedance inputs within their normal operating voltage ranges. An internal 2.6V clamp protects the device against excessive
input voltage and limits the maximum output current to approximately 4% above the maximum current set by VREF if the maximum input voltage is
exceeded.
Buck Topology
RS
In Buck mode, GI is connected to ADJ as in Figure 25. The LED current depends only
upon RS, VADJ and VREF. From Equation 1 above,
VIN
ISM
0.218
ILED
VADJ
VREF
REF
Equation 10
RSBUCK
ADJ
GI
If ADJ is directly connected to REF, this becomes:
0.218
ILED
RSBUCK
SGND
Figure 25 Setting LED Current in
Buck Configuration
Boost and Buck-Boost Topology
RS
For Boost and Buck-Boost topologies, the LED current depends upon the resistors, RS,
RGI1, and RGI2 as in Equations 4 and 2 above. There is more than one degree of freedom.
That is to say, there is not a unique solution. From Equation 4,
VIN
ISM
REF
0.225
ILED
VADJ
VREF
GI_ ADJ
Equation 11
RSBOOSTBB
ADJ
GI
If ADJ is connected to REF, this becomes:
RGI2
0.225
ILED
GI_ ADJ
RSBOOSTBB
RGI1
SGND
GI_ADJ is given by Equation 2, repeated here for convenience:
RGI1
GI_ ADJ
RGI1 RGI2
Figure 26 Setting LED Current in Boost
and Buck-Boost Configuration
Note that from considerations of ZXLD1370Q input bias current, the recommended limits for RGI1 are:
22kΩ < RGI1 < 100kΩ Equation 12
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Application Information (Cont.)
The additional degree of freedom allows us to select GI_ADJ within limits but this may affect overall performance a little. As mentioned above, the
working voltage range at the GI pin is restricted. The permitted range of GI_ADJ in Boost or Buck-Boost configuration is:
0.2 < GI_ADJ < 0.5
The mean voltage across the sense resistor is:
VRS = ICOIL RS
Equation 13
Equation 14
Note that if GI_ADJ is made larger, these equations show that RS is increased and VRS is increased. Therefore, for the same coil current, the
dissipation in RS is increased. So, in some cases, it is better to minimize GI_ADJ. However, consider Equation 5. If ADJ is connected to REF, this
becomes:
GI_ ADJ
0.225
VRS
1D
This shows that VRS becomes smaller than 225mV if GI_ADJ < 1 - D. If also D is small, VRS can become too small. For example if D = 0.2, and
GI_ADJ is the minimum value of 0.2, then VRS becomes 0.225* 0.2 / 0.8 = 56.25mV. This will increase the LED current error due to small offsets in
the system, such as mV drop in the copper printed wiring circuit, or offset uncertainty in the ZXLD1370Q. If now, GI_ADJ is increased to 0.4 or 0.5,
VRS is increased to a value greater than 100mV. This will give small enough ILED error for most practical purposes. Satisfactory operation will be
obtained if VRS is more than about 80mV. This means GI_ADJ should be greater than (1-DMIN) * 80/225 = (1- DMIN) * 0.355.
There is also a maximum limit on VRS which gives a maximum limit for GI_ADJ. If VRS exceeds approximately 300mV, or 133% of 225mV, the
STATUS output may indicate an overcurrent condition. This will happen for larger DMAX
Therefore, together with the requirement of Equation 13, the recommended range for GI_ADJ is:
0.355 ( 1-DMIN) < GI_ADJ < 1.33 ( 1-DMAX
.
)
Equation 15
Equation 16
An optimum compromise for GI_ADJ has been suggested, i.e.:
GI_ADJAUTO = 1 - DMAX
This value is used for the “Automatic” setting of the web Calculator. If 1-DMAX is less than 0.2, then GI_ADJ is set to 0.2. If 1- DMAX is greater than
0.5 then GI_ADJ is set to 0.5.
Once GI_ADJ has been selected, a value of RGI1 can be selected from Equation 12.
Then RGI2 is calculated as follows, rearranging Equation 2
1 GI_ ADJ
Equation 17
RGI2
R
GI1
GI_ ADJ
For example to drive 12 LEDS at a current of 350mA from a 12V supply requires Boost configuration. Each LED has a forward voltage of 3.2V at
350mA, so VOUT = 3.2*12 = 38.4V. From Equation 6, the duty cycle is approximately
VOUT
38.4 12
VIN
0.6875
38.4
VOUT
From Equation 16, we set GI_ADJ to 1 – D = 0.3125.
If RGI1 = 33kΩ, then from Equation 17,
1 0.3125
33x
72.6k
RGI2
0.3125
Let us choose the preferred value RGI2 = 75kΩ. Now GI_ADJ is adjusted to the new value, using Equation 2.
RGI1
33k
GI_ ADJ
0.305
RGI1RGI2
33k 75k
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Application Information (Cont.)
Now we calculate RS from Equation 11. Assume ADJ is connected to REF.
0.225
ILED
0.225
0.35
VADJ
VREF
xGI_ ADJx
x0.305 0.196
RSBOOSTBB
A preferred value of RSBOOSTBB = 0.2Ω will give the desired LED current with an error of 2% due to the preferred value selection.
Table 1 shows typical resistor values used to determine the GI_ADJ ratio with E24 series resistors.
Table 1
GI Ratio
0.2
RGI1
30kΩ
33kΩ
39kΩ
30kΩ
100kΩ
51kΩ
30kΩ
RG2
120kΩ
100kΩ
91kΩ
56kΩ
150kΩ
62kΩ
30kΩ
0.25
0.3
0.35
0.4
0.45
0.5
This completes the LED current setting.
Inductor Selection and Frequency Control
The selection of the inductor coil, L1, requires knowledge of the switching frequency and current ripple, and depends on the duty cycle to some
extent. In the hysteretic converter, the frequency depends upon the input and output voltages and the switching thresholds of the current monitor.
The peak-to-peak coil current is adjusted by the ZXLD1370Q to control the frequency to a fixed value. This is done by controlling the switching
thresholds within particular limits. This effectively much reduces the overall frequency range for a given input voltage range. Where the input
voltage range is not excessive, the frequency is regulated to approximately 330kHz in Buck configuration, and 300kHz in Boost and Buck-Boost
configurations. This is helpful in terms of EMC and other system requirements.
For larger input voltage variation, or when the choice of coil inductance is not optimum, the switching frequency may depart from the regulated
value, but the regulation of LED current remains successful. If desired, the frequency can to some extent be increased by using a smaller inductor,
or decreased using a larger inductor. The web Calculator will evaluate the frequency across the input voltage range and the effect of this upon
power efficiency and junction temperatures.
Determination of the input voltage range for which the frequency is regulated may be required. This calculation is very involved, and is not given
here. However, the performance in this respect can be evaluated within the web Calculator for the chosen inductance.
The inductance is given as follows in terms of peak-to-peak ripple current in the coil, ΔIL and the MOSFET on time, tON
.
tON
VIN VLED IOUT RDSON RCOIL RS
for Buck
IL
tON
L1 =
VIN
IIN RDSON RCOIL RS
for Boost
Equation 18
IL
tON
VIN
IOUT RDSON RCOIL RS
for Buck-Boost
I
IN
IL
Therefore In order to calculate L1, we need to find IIN, tON, and ΔIL. The effects of the resistances are small and will be estimated.
IIN is estimated from Equation 9.
tON is related to switching frequency, f, and duty cycle, D, as follows:
D
Equation 19
tON
f
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Application Information (Cont.)
As the regulated frequency is known, and we have already found D from Equation 7 or the approximation Equation 7a, this allows calculation of
tON
.
The ZXLD1370Q sets the ripple current, ΔIL is monitored by the ZXLD1370Q which sets this to be between nominally 10% and 30% of the mean
coil current, ICOIL, which is found from Equation 8. The device adjusts the ripple current within this range in order to regulate the switching
frequency. We therefore need to use a value of 20% of ICOIL to find an inductance which is optimized for the input voltage range. The range of
ripple current control is also modulated by other circuit parameters as follows.
1D
VADJ
VREF
0.03 0.12
ILMAX
ILMIN
ILMID
ICOIL
GI_ ADJ
1D
VADJ
VREF
Equation 20
0.01 0.04
ICOIL
GI_ ADJ
1D
VADJ
VREF
0.02 0.08
ICOIL
GI_ ADJ
If ADJ is connected to REF, this simplifies to:
1D
0.15
0.05
0.1
ILMAX
ILMIN
ILMID
ICOIL
GI_ ADJ
1D
Equation 20a
ICOIL
GI_ ADJ
1D
ICOIL
GI_ ADJ
Where ΔILMID is the value we must use in Equation 18. We have now established the inductance value.
The chosen coil should have a saturation current higher than the peak sensed current. This saturation current is the DC current for which the
inductance has decreased by 10% compared to the low current value.
Assuming 10% ripple current, we can find this peak current from Equation 8, adjusted for ripple current:
1.1 ILED
for Buck
ICOILPEAK
=
1.1 IINMAX
for Boost
Equation 21
1.1 IINMAX + ILED
for Buck-Boost
Where IINMAX is the value of IIN at minimum VIN.
The mean current rating is also a factor, but normally the saturation current is the limiting factor.
The following websites may be useful in finding suitable components:
www.coilcraft.com
www.niccomp.com
www.we-online.com/web/en/wuerth_elektronik/start.php
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Application Information (Cont.)
MOSFET Selection
The ZXLD1370Q requires an external NMOSFET as the main power switch with a voltage rating at least 15% higher than the maximum circuit
voltage to ensure safe operation during the overshoot and ringing of the switch node. The current rating is recommended to be at least 10% higher
than the average transistor current. The power rating is then verified by calculating the resistive and switching power losses.
P
PRESISTIVE PSWITCHING
Resistive Power Losses
The resistive power losses are calculated using the RMS transistor current and the MOSFET on-resistance.
Calculate the current for the different topologies as follows:
Buck Mode
IMOSFET MAX DMAX x ILED
When operating at low VIN in Buck mode a MOSFET with a suitably low VT must be chosen to ensure that the MOSFET is properly enhanced.
This is of most importance in Buck mode where a Bootstrap cannot be implemented.
Boost and Buck-Boost Mode
DMAX
iLED
IMOSFET MAX
1DMAX
When operating at low VIN in Boost or Buck-Boost modes a Bootstrap circuit (see Figure 37) to VAUX is recommended to fully enhance the external
MOSFET. If a Bootstrap circuit is not implemented, then a MOSFET with a suitably low VT must be chosen to ensure that the MOSFET is properly
enhanced.
The approximate RMS current in the MOSFET will be:
Buck Mode
IMOSFET RMS ILED
D
Boost and Buck-Boost Mode
D
IMOSFET RMS
x ILED
1D
The resistive power dissipation of the MOSFET is:
PRESISTIVE IMOSFET RMS 2 xRDSON
Switching Power Losses
Calculating the switching MOSFET's switching loss depends on many factors that influence both turn-on and turn-off. Using a first order rough
approximation, the switching power dissipation of the MOSFET is:
CRSS x V2 x fsw x ILOAD
IN
PSWITCHING
IGATE
Where:
CRSS is the MOSFET's reverse-transfer capacitance (a datasheet parameter),
fSW is the switching frequency,
IGATE is the MOSFET gate-driver's sink/source current at the MOSFET's turn-on threshold.
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ZXLD1370Q
Document number: DS37117 Rev. 4 - 2
ZXLD1370Q
Application Information (Cont.)
Matching the MOSFET with the controller is primarily based on the rise and fall time of the gate voltage. The best rise/fall time in the application is
based on many requirements, such as EMI (conducted and radiated), switching losses, lead/circuit inductance, switching frequency, etc. How fast
a MOSFET can be turned on and off is related to how fast the gate capacitance of the MOSFET can be charged and discharged. The relationship
between C (and the relative total gate charge QG), turn-on/turn-off time and the MOSFET driver current rating can be written as:
dV C Qg
dt
I
I
Where
dt = turn-on/turn-off time
dV = gate voltage
C = gate capacitance = QG/V
I = drive current – constant current source (for the given voltage value)
Here the constant current source “I” usually is approximated with the peak drive current at a given driver input voltage.
(Example 1)
Using the DMN6068 MOSFET (VDS(MAX) = 60V, ID(MAX) = 8.5A):
QG = 10.3nC at VGS = 10V
ZXLD1370Q IPEAK = I GATE = 300mA
Qg
10.3nC
dt
35ns
IPEAK 300mA
Assuming that cumulatively the rise time and fall time can account for a maximum of 10% of the period, the maximum frequency allowed in this
condition is:
tPERIOD = 20*dt
f = 1/ tPERIOD = 1.43MHz
This frequency is well above the max frequency the device can handle, therefore the DNM6068 can be used with the ZXLD1370Q in the whole
spectrum of frequencies recommended for the device (from 300kHz to 1MHz).
(Example 2)
Using the ZXMN6A09KQ (VDS(MAX) = 60V, ID(MAX) = 12.2A):
QG = 29nC at VGS = 10V
ZXLD1370Q IPEAK = 300mA
Qg
IPEAK 300mA
29nC
dt
97ns
Assuming that cumulatively the rise time and fall time can account for a maximum of 10% of the period, the maximum frequency allowed in this
condition is:
tPERIOD = 20*dt
f = 1/ tPERIOD = 515kHz
This frequency is within the recommended frequency range the device can handle, therefore the ZXMN6A09K is recommended to be used with
the ZXLD1370Q for frequencies from 300kHz to 500kHz.
The recommended total gate charge for the MOSFET used in conjunction with the ZXLD1370Q is less than 30nC.
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Document number: DS37117 Rev. 4 - 2
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Application Information (Cont.)
Junction Temperature Estimation
Finally, the ZXLD1370Q junction temperature can be estimated using the following equations:
Total supply current of ZXLD1370Q:
IQTOT ≈ IQ + f • QG
Where IQ = total quiescent current IQ-IN + IQ-AUX
Power consumed by ZXLD1370Q:
PIC = VIN • (IQ + f • Qg)
Or in case of separate voltage supply, with VAUX < 15V:
PIC = VIN • IQ-IN + VAUX • (IQ-AUX + f • Qg)
TJ = TA + PIC • JA = TA + PIC • (JC + CA)
Where the total quiescent current IQTOT consists of the static supply current (IQ) and the current required to charge and discharge the gate of the
power MOSFET. Moreover, the part of thermal resistance between case and ambient depends on the PCB characteristics.
Figure 27 Power Derating Curve for ZXLD1370Q Mounted on Test Board According to JESD51
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Document number: DS37117 Rev. 4 - 2
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Application Information (Cont.)
Diodes Selection
For maximum efficiency and performance, the rectifier (D1) should be a fast low capacitance Schottky diode* with low reverse leakage at the
maximum operating voltage and temperature. The Schottky diode also provides better efficiency than silicon PN diodes, due to a combination of
lower forward voltage and reduced recovery time.
It is important to select parts with a peak current rating above the peak coil current and a continuous current rating higher than the maximum
output load current. In particular, it is recommended to have a voltage rating at least 15% higher than the maximum transistor voltage to ensure
safe operation during the ringing of the switch node and a current rating at least 10% higher than the average diode current. The power rating is
verified by calculating the power loss through the diode.
The higher forward voltage and overshoot due to reverse recovery time in silicon diodes will increase the peak voltage on the Drain of the external
MOSFET. If a silicon diode is used, care should be taken to ensure that the total voltage appearing on the Drain of the external MOSFET,
including supply ripple, does not exceed the specified maximum value.
*A suitable Schottky diode would be PDS3100Q (Diodes Incorporated).
Output Capacitor
An output capacitor may be required to limit interference or for specific EMC purposes. For boost and buck-boost regulators, the output capacitor
provides energy to the load when the freewheeling diode is reverse biased during the first switching subinterval. An output capacitor in a buck
topology will simply reduce the LED current ripple below the inductor current ripple. In other words, this capacitor changes the current waveform
through the LED(s) from a triangular ramp to a more sinusoidal version without altering the mean current value.
In all cases, the output capacitor is chosen to provide a desired current ripple of the LED current (usually recommended to be less than 40% of the
average LED current).
Buck
ILPP
COUTPUT
8xfSW xrLED xILEDPP
Boost and Buck-Boost
DxILEDPP
COUTPUT
fSW xrLED xILEDPP
Where:
IL-PP is the ripple of the inductor current, usually 20% of the average sensed current
ILED-PP is the ripple of the LED current, it should be <40% of the LEDs average current
fSW is the switching frequency (From graphs and calculator)
rLED is the dynamic resistance of the LEDs string (n times the dynamic resistance of the single LED from the
data sheet of the LED manufacturer).
The output capacitor should be chosen to account for derating due to temperature and operating voltage. It must also have the necessary RMS
current rating. The minimum RMS current for the output capacitor is calculated as follows:
Buck
ILEDPP
ICOUTPUT
RMS
12
Boost and Buck-Boost
DMAX
ICOUTPUTRMS ILED
1DMAX
Ceramic capacitors with X7R dielectric are the best choice due to their high ripple current rating, long lifetime, and performance over the voltage
and temperature ranges.
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ZXLD1370Q
Application Information (Cont.)
Input Capacitor
The input capacitor can be calculated knowing the input voltage ripple VIN-PP as follows:
Buck
Dx(1 D)xILED
CIN
Use D = 0.5 as worst case
fSW xV
INPP
Boost
ILPP
CIN
8xfSW xV
INPP
Buck-Boost
DxILED
Use D = DMAX as worst case
CIN
fSW x V
INPP
The minimum RMS current for the output capacitor is calculated as follows:
Buck
Use D = 0.5 as worst case
ICINRMS ILEDx Dx(1D)
Boost
ILPP
ICIN
RMS
12
Buck-Boost
D
ICINRMS ILED
x
Use D = DMAX as worst case
(1D)
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Application Information (Cont.)
PWM Output Current Control & Dimming
The ZXLD1370Q has a dedicated PWM dimming input that allows a wide dimming frequency range from 100Hz to 1kHz with up to 1000:1
resolution; however higher dimming frequencies can be used – at the expense of dimming dynamic range and accuracy.
Typically, for a PWM frequency of 1kHz, the error on the current linearity is lower than 5%; in particular the accuracy is better than 1% for PWM
from 5% to 100%. This is shown in the graph below:
Buck mode - L=33uH - Rs = 150mΩ - PWM @ 1kHz
1500.00
1250.00
1000.00
750.00
500.00
250.00
0.00
10%
9%
8%
7%
6%
5%
4%
3%
2%
1%
0%
0
10
20
30
40
50
60
70
80
90
100
PWM
PWM @ 1kHz
Error
Figure 28 LED Current Linearity and Accuracy with PWM Dimming at 1kHz
For a PWM frequency of 100Hz, the error on the current linearity is lower than 2.5%; it becomes negligible for PWM greater than 5%. This is
shown in the graph below:
Buck mode - L=33uH - Rs = 150mΩ - PWM @ 100Hz
1500.00
1250.00
1000.00
750.00
500.00
250.00
0.00
10%
9%
8%
7%
6%
5%
4%
3%
2%
1%
0%
0
10
20
30
40
50
60
70
80
90
100
PWM
PWM @ 100Hz
Error
Figure 29 LED Current Linearity and Accuracy with PWM Dimming at 100Hz
The PWM pin is designed to be driven by both 3.3V and 5V logic levels. It can be driven also by an open drain/collector transistor. In this case, the
designer can either use the internal pull-up network or an external pull-up network in order to speed up PWM transitions, as shown in the Boost
and Buck-Boost section.
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Document number: DS37117 Rev. 4 - 2
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Application Information (Cont.)
2µ s
< 10ms
Gate
ZXLD1370Q
0V
Figure 30 PWM Dimming from Open Collector Switch
PWM
< 10 ms
ZXLD1370Q
0V
2µ s
Figure 32 PWM Dimming Minimum and Maximum Pulse
Figure 31 PWM Dimming from MCU
LED current can be adjusted digitally, by applying a low frequency PWM logic signal to the PWM pin to turn the controller on and off. This will
produce an average output current proportional to the duty cycle of the control signal. During PWM operation, the device remains powered
up and only the output switch is gated by the control signal.
The PWM signal can achieve very high LED current resolution. In fact, dimming down from 100% to 0.1% at 500Hz, a minimum pulse width
of 2µs can be achieved resulting in very high resolution and accuracy. While the maximum recommended pulse is for the PWM signal is
10ms (equivalent to 100Hz) (see Figure 32).
The ultimate PWM dimming ratio will be determined by the
switching frequency as the minimum PWM pulse width is
determined by resolving at least 1 switching cycle. The figure to the
right shows the switching waveforms for a low duty cycle PWM
dimming.
As can be seen, when the LED current restarts (blue waveform) it
has to start all the way from zero to the peak level set by
VSENSE/RS*1.15. Therefore, the first pulse is always longer than the
nominal switching frequency would imply.
STATUS
Standby
state
0V
The PWM pin can be used to put the device into standby. Taking
the PWM pin low (<0.4V) for more than 25ms (typically 15ms) the
device will enter its standby state and most of the internal circuitry
is switched off and residual quiescent current will be typically 90µA.
In particular, the STATUS pin will go down to GND while the FLAG
and REF pins will stay at their nominal values.
PWM
0V
~15ms
Figure 33 Standby State from PWM Signal
When the device restarts from standby mode, a “start-up” time must be allowed for before the device resume full LED current regulation.
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Application Information (Cont.)
Thermal Control of LED Current
For thermal control of the LEDs, the ZXLD1370Q monitors the voltage on the TADJ pin and reduces output current if the voltage on this pin falls
below 625mV. An external NTC thermistor and resistor can therefore be connected as shown below to set the voltage on the TADJ pin to 625mV
at the required temperature threshold. This will give 100% LED current below the threshold temperature and a falling current above it as shown in
the graph. The temperature threshold can be altered by adjusting the value of RTH and/or the thermistor to suit the requirements of the chosen
LED.
The Thermal Control feature can be disabled by connecting TADJ directly to REF.
Here is a simple procedure to design the thermal feedback circuit:
(1) Select the temperature threshold TTHRESHOLD at which the current must start to decrease
(2) Select the Thermistor TH1 (both resistive value at +25°C and beta)
(3) Select the value of the resistor RTH as RTH = TH at TTHRESHOLD
ILED
REF
Rth
100%
TADJ
TH1
10%
70˚C
85˚C
TLED
Thermal network response in Buck configuration with:
Rth = 1.8kΩ and TH1=10kΩ (beta =3900)
Figure 34 Thermal Feedback Network
The thermistor resistance, RT, at a temperature of T degrees Kelvin is given by:
1
T
1
B
TR
RT RR
e
Where:
RR is the thermistor resistance at the reference temperature, TR
TR is the reference temperature, in Kelvin, normally 273 + 25 = 298K (+25°C)
B is the “beta” value of the thermistor.
For example,
(1) Temperature threshold TTHRESHOLD = 273 + 70 = 343K (+70°C)
(2) TH1 = 10kΩ at +25°C and B = 3900 RT = 1.8kΩ @ +70°C
(3) RTH = RT at TTHRESHOLD = 1.8kΩ
Overtemperature Shutdown
The ZXLD1370Q incorporates an overtemperature shutdown circuit to protect against damage caused by excessive die temperature. A warning
signal is generated on the STATUS output when die temperature exceeds +125°C nominal and the output is disabled when die temperature
exceeds +150°C nominal. Normal operation resumes when the device cools back down to +125°C.
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Application Information (Cont.)
FLAG/STATUS Outputs
The FLAG/STATUS outputs provide a warning of extreme operating or fault conditions. FLAG is an open-drain logic output, which is normally off,
but switches low to indicate that a warning, or fault condition exists. STATUS is a DAC output, which is normally high (4.5V), but switches to a
lower voltage to indicate the nature of the warning/fault.
Conditions monitored, the method of detection and the nominal STATUS output voltage are given in the following table:
Table 2
Severity
(Note 18)
Warning/Fault Condition
Normal Operation
Monitored Parameters
FLAG
Nominal STATUS Voltage
—
1
—
H
L
L
4.5
4.5
3.6
VAUX<5.6V
VIN<5.6V
Supply Undervoltage
2
Output Current Out of Regulation
(Note 19)
VSHP Outside Normal Voltage
Range
2
2
3
4
L
L
L
L
3.6
3.6
1.8
0.9
Driver Stalled with switch ‘On’, or ‘Off’
(Note 20)
tON, or tOFF>100µ s
TJ>+125°C
Device Temperature Above Maximum
Recommended Operating Value
Sense Resistor Current IRS Above
Specified Maximum
VSENSE>0.32V
Notes:
18. Severity 1 denotes lowest severity.
19. This warning will be indicated if the output power demand is higher than the available input power; the loop may not be able to maintain regulation.
20. This warning will be indicated if the GATE pin stays at the same level for greater than 100µs (e.g., the output transistor cannot pass enough current
to reach the upper switching threshold).
VREF
0V
4.5V
Normal
Operations
VAUX
UVLO
3.6V
2.7V
1.8V
- VIN UVLO
- STALL
- OUT of REG
Over
Temperature
0.9V
Over
Current
0A
3
4
2
1
0
SEVERITY
Figure 35 Status Levels
In the event of more than one fault/warning condition occurring, the higher severity condition will take precedence. E.g., ‘Excessive Coil Current’
and ‘Out of Regulation’ occurring together will produce an output of 0.9V on the STATUS pin.
If VADJ>1.7V, VSENSE may be greater than the excess coil current threshold in normal operation and an error will be reported. Hence, STATUS and
FLAG are only guaranteed for VADJ<=VREF
.
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Application Information (Cont.)
Diagnostic signals should be ignored during the device start-
up for 100μs. The device start up sequence will be initiated
both during the first power on of the device or after the PWM
signal is kept low for more than 15ms, initiating the standby
state of the device.
VREF
0V
Out of
regulation
Over
Current
In particular, during the first 100μs the diagnostic is signaling
an overcurrent then an out-of-regulation status. These two
events are due to the charging of the inductor and are not true
fault conditions.
225mV/R1
0A
100us
Figure 36 Diagnostic During Start-Up
Boosting VAUX Supply Voltage in Boost and Buck-Boost Mode
When the input voltage is lower than 8V, the gate voltage will be around 6.5V or lower. This means that depending on the characteristics of the
external MOSFET, the gate voltage may not be enough to fully enhance the power MOSFET. This boosting technique is particularly important
when the output MOSFET is operating at full current, since the boost circuit allows the gate voltage to be higher than 12V. This guarantees that
the MOSFET is fully enhanced reducing both the power dissipation and the risk of thermal runaway of the MOSFET itself. An extra diode D2 and
decoupling capacitor C3 can be used, as shown below in Figure 37, to generate a boosted voltage at VAUX when the input supply voltage at VIN is
below 8V. This enables the device to operate with full output current when VIN is at the minimum value of 6V. In the case of a low voltage
threshold MOSFET, the bootstrap circuit is generally not required.
LED1..n
D1
C3
D3
D2
VIN
Buck-Boost
mode
Boost
mode
R2
R1
L
Drain of
external
switch
ISM
VIN
VAUX
Figure 37 Bootstrap Circuit for Boost and Buck-Boost Low Voltage Operations
The resistor R2 can be used to limit the current in the bootstrap circuit in order to reduce the impact of the circuit itself on the LED accuracy. The
impact on the LED current is usually a decrease of maximum 5% compared to the nominal current value set by the sense resistor.
The Zener diode D3 is used to limit the voltage on the VAUX pin to less than 60V.
Due to the increased number of components and the loss of current accuracy, the bootstrap circuit is recommended only when the system has to
operate continuously in conditions of low input voltage (between 6 and 8V) and high load current. Other circumstances such as low input voltage
at low load current, or transient low input voltage at high current should be evaluated keeping account of the external MOSFET power dissipation.
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Application Information (Cont.)
Overvoltage Protection
The ZXLD1370Q is inherently protected against open-circuit load when used in Buck configuration. However care has to be taken with open-circuit
load conditions in Buck-Boost or Boost configurations. This is because in these configurations there is no internal open-circuit protection
mechanism for the external MOSFET. In this case, an Overvoltage Protection (OVP) network should be provided externally to the MOSFET to
avoid damage due to open circuit conditions. This is shown in Figure 38 below, highlighted in the dotted blue box.
Figure 38 OVP Circuit
The Zener voltage is determined according to: VZ = VLEDMAX +10% where VLEDMAX is maximum LED chain voltage.
If the LEDA voltage exceeds VZ the gate of MOSFET Q2 will rise turning Q2 on. This will pull the PWM pin low and switch off Q1 until the voltage
on the drain of Q1 falls below VZ. If the voltage at LEDA remains above VZ for longer than 20ms then the ZXLD1370Q will enter into a shutdown
state.
Care should be taken such that the maximum gate voltage of the Q2 MOSFET is not exceeded.
Take care of the max voltage drop on the Q2 MOSFET gate.
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Application Information (Cont.)
PCB Layout Considerations
PCB layout is a fundamental activity to get the most of the device in all configurations. In the following section, it is possible to find some important
insight to design with the ZXLD1370Q both in Buck and Buck-Boost configurations.
SHP Pin
Inductor, Switch and
Freewheeling Diode
VIN / VAUX
Decoupling
Figure 39 Circuit Layout
Here are some considerations useful for the PCB layout:
In order to avoid ringing due to stray inductances, the inductor L1, the anode of D1 and the drain of Q1 should be placed as close together as
possible.
The shaping capacitor C1 is fundamental for the stability of the control loop. To this end it should be placed no more than 5mm from the SHP
pin.
Input voltage pins, VIN and VAUX, need to be decoupled. It is recommended to use two ceramic capacitors of 2.2µF, X7R, 100V (C3 and C4).
In addition to these capacitors, it is suggested to add two ceramic capacitors of 1F, X7R, 100V each (C2, C8), as well as a further decoupling
capacitor of 100nF close to the VIN/VAUX pins (C9). VIN and VAUX pins can be short-circuited when the device is used in buck mode, or
can be driven from a separate supply.
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Application Information (Cont.)
Application Examples
Example 1: 2.8A Buck LED Driver
In this application example, the ZXLD1370Q is connected as a buck LED driver. The schematic and parts list are shown below. The LED driver is
able to deliver 2.8A of LED current with an input voltage range of 8V to 24V. In order to achieve high efficiency at high LED current, a Super
Barrier Rectifier (SBR®) with a low forward voltage is used as the freewheeling rectifier.
This LED driver is suitable for applications which require high LED current such as LED projector, automatic LED lighting, etc.
FLAG
Figure 40 Application Circuit: 2.8A Buck LED Driver
Table 3: Bill of Material
Ref Number
Value
60V LED Driver
60V MOSFET
45V 10A SBR
33µH 4.2A
Part Number
ZXLD1370Q
ZXMN6A09K
SBR10U45SP5
744770933
Manufacturer
Diodes Incorporated
Diodes Incorporated
Diodes Incorporated
Würth Elektronik
Generic
U1
Q1
D1
L1
C1
100pF 50V
1µF 50V X7R
4.7µF 50V X7R
300mΩ 1%
400mΩ 1%
0Ω
SMD 0805/0603
SMD1206
C2
Generic
C3 C4 C5
R1 R2 R3
R4
SMD1210
Generic
SMD1206
Generic
SMD1206
Generic
R5
SMD 0805/0603
Generic
SBR is a registered trademark of Diodes Incorporated.
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Application Information (Cont.)
Typical Performance
LED Current vs Input Voltage
Efficiency vs Input Voltage
3000
2500
2000
1500
1000
500
100%
90%
80%
70%
60%
50%
40%
30%
20%
10%
0%
1 LED
2 LED
0
10
12
14
16
18
20
22
24
10
12
14
16
18
20
22
24
Input Voltage (V)
Input Voltage (V)
Figure 41 Efficiency
Example 2: 400mA Boost LED Driver
Figure 42 Line Regulation
In this application example, the ZXLD1370Q is connected as a boost LED driver. The schematic and parts list are shown below. The LED driver is
able to deliver 400mA of LED current into 12 high-brightness LEDs with an input voltage range of 16V to 32V.
The overall high efficiency of 92%+ makes it ideal for applications such as solar LED street lighting and general LED illuminations.
Figure 43 Application Circuit - 400mA Boost LED Driver
Table 4: Bill of Material
Ref Number
U1
Value
60V LED Driver
60V MOSFET
60V MOSFET
100V 3A Schottky
47V 410mW Zener
68µH 2.1A
Part Number
ZXLD1370Q
ZXMN6A25G
2N7002A
Manufacturer
Diodes Incorporated
Diodes Incorporated
Diodes Incorporated
Diodes Incorporated
Diodes Incorporated
Würth Elektronik
Generic
Q1
Q2
D1
PDS3100-13
BZT52C47
Z1
L1
744771168
C1
100pF 50V
SMD 0805/0603
SMD1210
C3 C9
C2
4.7µF 50V X7R
1µF 50V X7R
560mΩ 1%
33kΩ 1%
Generic
SMD1206
Generic
R1 R2
R9 R10
R12
SMD1206
Generic
SMD 0805/0603
SMD 0805/0603
SMD 0805/0603
Generic
0Ω
Generic
R15
2.7kΩ
Generic
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Application Information (Cont.)
400mA Boost LED Driver Typical Performance
Efficiency vs Input Voltage
LED Current vs Input Voltage
100%
450
400
350
300
250
200
150
100
50
90%
80%
70%
60%
50%
40%
30%
20%
10%
0%
0
16
18
20
22
24
26
28
30
32
16
18
20
22
24
26
28
30
32
Input Voltage
Input Voltage
Figure 44 Efficiency
Example 3: 700mA Buck-Boost LED Driver
Figure 45 Line Regulation
In this application example, the ZXLD1370Q is connected as a Buck-Boost LED driver. The schematic and parts list are shown below. The LED
driver is able to deliver 700mA of LED current into 4 high-brightness LEDs with an input voltage range of 7V to 20V.
Since the Buck-Boost LED driver handles an input voltage range from below and above the total LED voltage, the versatile input voltage range
makes it ideal for automotive lighting applications.
Figure 46 Application Circuit - 700mA Buck-Boost LED Driver
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Application Information (Cont.)
Table 5: Bill of Material
Ref Number
Value
Part Number
ZXLD1370Q
ZXMN6A25G
2N7002A
Manufacturer
U1
Q1
Q2
60V LED Driver
60V MOSFET
60V MOSFET
Diodes Incorporated
Diodes Incorporated
Diodes Incorporated
Diodes Incorporated
Diodes Incorporated
Würth Elektronik
Generic
D1
Z1
100V 5A Schottky
47V 410mW Zener
22µH 2.1A
100pF 50V
4.7µF 50V X7R
1µF 50V X7R
300mΩ 1%
33kΩ 1%
PDS5100-13
BZT52C47
L1
744771122
C1
SMD 0805/0603
SMD1210
C3 C9
C2
Generic
SMD1206
Generic
R1 R2 R3
R9
SMD1206
Generic
SMD 0805/0603
SMD 0805/0603
SMD 0805/0603
SMD 0805/0603
Generic
R10
R12
R15
15kΩ 1%
Generic
0Ω
Generic
2.7kΩ
Generic
700mA Buck-Boost LED Driver Typical Performance
Efficiency vs Input Voltage
LED Current vs Input Voltage
100%
800
700
600
500
400
300
200
100
0
90%
80%
70%
60%
50%
40%
30%
20%
10%
0%
7
8
9
10 11 12 13 14 15 16 17 18 19 20
7
8
9
10
11
12
13
14
15
16
17
18
19
20
Input Voltage
Input Voltage
Figure 47 Efficiency
Figure 48 Line Regulation
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© Diodes Incorporated
ZXLD1370Q
Document number: DS37117 Rev. 4 - 2
ZXLD1370Q
Ordering Information
Packing: 13” Tape and Reel
Packaging
(Note 21)
Package
Code
Qualification
(Note 22)
Part Number
Reel Quantity
Tape Width
Part Number Suffix
ZXLD1370QESTTC
TSSOP-16EP
EST
2,500
16mm
TC
Automotive Compliant
Notes: 21. For packaging details, go to our website at https://www.diodes.com/design/support/packaging/diodes-packaging/.
22. ZXLD1370Q has been qualified to AEC-Q100 grade 1 and is classified as “Automotive Compliant” supporting PPAP documentation.
See ZXLD1370 datasheet for commercial qualified versions.
Marking Information
TSSOP-16EP
ZXLD1370 = Product Type Marking Code
YYWW = Date Code Marking
YY = Last Two Digits of Year (ex: 18 = 2018)
WW = Week: 01 to 52; 52 represents 52 and 53 week
A = Internal Code
37 of 39
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© Diodes Incorporated
ZXLD1370Q
Document number: DS37117 Rev. 4 - 2
ZXLD1370Q
Package Outline Dimensions
Please see http://www.diodes.com/package-outlines.html for the latest version.
TSSOP-16EP
D
X
TSSOP-16EP
Max
e
Dim
A
Min
-
Typ
-
1.20
A1
A2
b
0.025 0.100
-
0.80
0.19
0.09
4.90
6.20
4.30
1.05
0.30
0.20
5.10
6.60
0.90
-
-
5.00
6.40
4.40
E1
E
Y
c
D
E
E1
e
PIN 1
4.50
ID MARK
0.65 BSC
L
0.45
0.75 0.60
1.0 REF
0.65 BSC
A2
0.25
L1
L2
X
Y
θ1
Gauge Plane
A
-
-
0°
-
-
8°
2.997
2.997
-
Seating Plane
DETAIL
b
A1
L
All Dimensions in mm
L1
Suggested Pad Layout
Please see http://www.diodes.com/package-outlines.html for the latest version.
TSSOP-16EP
X2
Value
Dimensions
(in mm)
0.650
0.450
3.290
5.000
1.450
3.290
4.450
7.350
Y
C
X
X1
X2
Y
Y3
Y1
Y2
X1
Y1
Y2
Y3
C
X
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February 2018
© Diodes Incorporated
ZXLD1370Q
Document number: DS37117 Rev. 4 - 2
ZXLD1370Q
IMPORTANT NOTICE
DIODES INCORPORATED MAKES NO WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, WITH REGARDS TO THIS DOCUMENT,
INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
(AND THEIR EQUIVALENTS UNDER THE LAWS OF ANY JURISDICTION).
Diodes Incorporated and its subsidiaries reserve the right to make modifications, enhancements, improvements, corrections or other changes
without further notice to this document and any product described herein. Diodes Incorporated does not assume any liability arising out of the
application or use of this document or any product described herein; neither does Diodes Incorporated convey any license under its patent or
trademark rights, nor the rights of others. Any Customer or user of this document or products described herein in such applications shall assume
all risks of such use and will agree to hold Diodes Incorporated and all the companies whose products are represented on Diodes Incorporated
website, harmless against all damages.
Diodes Incorporated does not warrant or accept any liability whatsoever in respect of any products purchased through unauthorized sales channel.
Should Customers purchase or use Diodes Incorporated products for any unintended or unauthorized application, Customers shall indemnify and
hold Diodes Incorporated and its representatives harmless against all claims, damages, expenses, and attorney fees arising out of, directly or
indirectly, any claim of personal injury or death associated with such unintended or unauthorized application.
Products described herein may be covered by one or more United States, international or foreign patents pending. Product names and markings
noted herein may also be covered by one or more United States, international or foreign trademarks.
This document is written in English but may be translated into multiple languages for reference. Only the English version of this document is the
final and determinative format released by Diodes Incorporated.
LIFE SUPPORT
Diodes Incorporated products are specifically not authorized for use as critical components in life support devices or systems without the express
written approval of the Chief Executive Officer of Diodes Incorporated. As used herein:
A. Life support devices or systems are devices or systems which:
1. are intended to implant into the body, or
2. support or sustain life and whose failure to perform when properly used in accordance with instructions for use provided in the
labeling can be reasonably expected to result in significant injury to the user.
B. A critical component is any component in a life support device or system whose failure to perform can be reasonably expected to cause the
failure of the life support device or to affect its safety or effectiveness.
Customers represent that they have all necessary expertise in the safety and regulatory ramifications of their life support devices or systems, and
acknowledge and agree that they are solely responsible for all legal, regulatory and safety-related requirements concerning their products and any
use of Diodes Incorporated products in such safety-critical, life support devices or systems, notwithstanding any devices- or systems-related
information or support that may be provided by Diodes Incorporated. Further, Customers must fully indemnify Diodes Incorporated and its
representatives against any damages arising out of the use of Diodes Incorporated products in such safety-critical, life support devices or systems.
Copyright © 2018, Diodes Incorporated
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© Diodes Incorporated
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Document number: DS37117 Rev. 4 - 2
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