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OB3372
High Power Dual output LED Driver
GENERAL DESCRIPTION
The OB3372 is a high power dual output LED
driver optimized for large size LED backlighting
application. It integrates two independent boost
converters, providing a high performance and high
reliability LED backlighting solution.
It incorporates two boost converters operating in
current mode PWM control at fixed frequency. The
operation frequency is programmed from 100 kHz
to 600 kHz by setting an external resistor at RT
pin.
The OB3372 can be configured for Master-Slave
operation to support multi-channel applications.
The voltage across LED current sense resistor is
regulated to about 600mV to reduce power loss
and improve efficiency.
The external PWM dimming mode is supported.
The PWM dimming signal is injected externally
from DIM pin.
The OB3372 offers comprehensive protection
such as power MOSFET over current protection
(OCP), output over voltage protection (OVP), IC
power supply under voltage lockout (UVLO), and
LED open & short protection.
FEATURES
„ High Power Dual Output PWM Control
„ 8V to 35V Input Voltage Range
„ Master/Slave Synchronization Capability
„ Programmable 100kHz~600kHz Operation
Frequency
„ Programmable Slope Compensation
„ External PWM Dimming Mode
„ Over Voltage Protection
„ Over Current Protection
„ Under Voltage Lockout (UVLO)
„ LED Open Protection
„ LED Short Protection
APPLICATIONS
„ LCD TV
„ LCD Monitor
„ Flat panel display
TYPICAL APPLICATION
L2
D2
VIN
GND
ENA
DIM
CIN
SYNC
Fault
Driver
Circuit
Q5
L1
RSC
RRT
CCMP1
CCMP2
CHCP
1 SC
VIN 20
2 RT
GATE2 19
3 CMP1
GATE1 18
4 CMP2
GND 17
OB33725 HCP
6 SYNC
CS2 16
CS1 15
7 ENA
LSD2 14
8 DIM
FB2 13
9 OVP1
LSD1 12
10 OVP2
FB1 11
CVIN
Q2
Q1
RCS1
RCS2
D1
ROVP2A
ROVP2B
CO2
ROVP1A CO1
ROVP1B
Q3
RFB1
Q4
RFB2
Figure1: OB3372 Typical Application Schematic
©On-Bright Electronics
Confidential
-1-
Preliminary Datasheet
OB_DOC_DS_337202

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OB3372
High Power Dual Output LED Driver
Absolute Maximum Ratings
Parameter
Vin Input Voltage to GND
GATE / LSD to GND
I/O (except GATE/LSD) to
GND
Operating Ambient Temp. TA
Operating Junction Temp. TJ
Min/Max Storage Temp. Tstg
Lead Temp. (10 Sec)
Value
-0.3V to 40V
-0.3V to 40V
-0.3V to 7V
-20~ 85
-40 ~150
-55 ~150
260
Note: Stresses beyond those listed under “absolute maximum
ratings” may cause permanent damage to the device. These
are stress ratings only, functional operation of the device at
these or any other conditions beyond those indicated under
“recommended operating conditions” is not implied. Exposure
to absolute maximum-rated conditions for extended periods
may affect device reliability.
Recommended Operating Range
Parameter
Vin Voltage
Operating Frequency
Value
8V to 35V
100k~600k
Ordering Information
Part Number
OB3372KP
OB3372LP
Description
SOP20, pb-free in tube
SSOP20, pb-free in tube
Marking Information
Y:Year Code
WW:Week Code(01-52)
ZZZ:Lot Code
L:SSOP20 Package
P:Pb-free Package
S:Internal Code(Optional)
©On-Bright Electronics
Confidential
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Preliminary Datasheet
OB_DOC_DS_337202

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OB3372
High Power Dual Output LED Driver
Pin Configuration for OB3372KP/LP
SC
RT
CMP1
CMP2
HCP
SYNC
ENA
DIM
OVP1
OVP2
1
2
3
4
5
6
7
8
9
10
20 VIN
19 GATE2
18 GATE1
17 GND
16 CS2
15 CS1
14 LSD2
13 FB2
12 LSD1
11 FB1
Terminal Assignment for OB3372KP/LP
Number Pin Name I/O
Pin Function
1 SC Output Connect an external resistor to GND for slope compensation setup
This pin is pulled to 5V when there is an output short circuit condition
or DC/DC loop disconnection condition
2 RT I/O Connect an external resistor to GND to set master operation mode
and to set boost converter switching frequency
Connect an external capacitor to GND to set slave operation mode
and to set internal PLL loop compensation
3
CMP1
I/O
Loop compensation for channel1
4
CMP2
I/O
Loop compensation for channel2
5
HCP
I/O Hiccup timer setting
6
OVP1
Input Output over voltage protection sense for channel 1
7
OVP2
Input Output over voltage protection sense for channel 2
8
SYNC
I/O
Input/output signal for operation frequency synchronization
9
ENA
Input Chip enable control
10 DIM Input External PWM dimming control
11 FB1 Input LED current feedback input for channel1
12
LSD1
Output This pin is used to drive an external MOSFET which disconnects the
load from the circuit during a fault condition or during PWM dimming
for channel1
13 FB2 Input LED current feedback input for channel2
14
LSD2
Output This pin is used to drive an external MOSFET which disconnects the
load from the circuit during a fault condition or during PWM dimming
for channel2
15 CS1 Input Current sense input for GATE1
16 CS2 Input Current sense input for GATE2
©On-Bright Electronics
Confidential
-3-
Preliminary Datasheet
OB_DOC_DS_337202

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OB3372
High Power Dual Output LED Driver
Number
17
18
19
20
Pin Name I/O
GND
Ground
GATE1
Output
GATE2
Output
VIN Power
Pin Function
Power ground
Gate drive output for channel1
Gate drive output for channel2
Power supply
Functional Block Diagram
ENA
OVP1
OVP2
DIM
VIN
Vref
Reference
& LDO
Iref
5V
Enable Enable
OVP
SENSE
5V
4uA
HCP
Ramp
S
PWM_DIM
+ Gate
- control
- 600mv
EA
+
Dimming and
Counter
PWM_DIM
Drive
Drive
RT
SYNC
5V
OSC
and
Sync
CLK
Slope Ramp
compeasation
Ramp
S
+
EA
- 600mv
-
Gate
+ control
PWM_DIM
SC GND
Figure2: OB3372 Functional Block Diagram
CS2
GATE2
FB2
CMP2
LSD2
LSD1
CMP1
FB1
GATE1
CS1
©On-Bright Electronics
Confidential
-4-
Preliminary Datasheet
OB_DOC_DS_337202

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OB3372
High Power Dual Output LED Driver
Electrical Characteristics
VIN=12V, ENA=5V, RT=20k ohm to ground, TA=25, if not otherwise noted.
Parameter
Symbol
Test Conditions
Min Tyc Max Unit
Supply Voltage
Operating
Input
Voltage
Supply
(Quiescent)
Supply
(Disable)
Current
Current
UVLO(OFF)
UVLO (ON)
ENA ON Threshold
ENA OFF Threshold
ENA pull down resistor
RT Voltage
Oscillator
Operation Frequency
Operation Frequency
SYNC input high
voltage
SYNC input
voltage
low
SYNC rising time
SYNC falling time
PWM Control
Feedback voltage for
FB
Lead edge blanking
time
Maximum Duty Cycle
Slope rate of soft start
Error Amplifier
Input common-mode
range
Output voltage range
Transconductance
Maximum
Current
Output
PWM Dimming
DIM High Threshold
DIM Low Threshold
Gate drive
Clamp of GATE output
GATE rising time
GATE falling time
Protection
OVP Over Voltage
Threshold
FAULT
protection
threshold
Blanking time of LED
fault detection
VIN
IVIN-op
IVIN-disable
UVLO_off
UVLO_on
ENA_on
ENA_off
RENA
VRT
Fop
Fop
VSYNC-H
VSYNC-L
Tr_sync
Tf_sync
VFB
TLEB
Dutymax
SRSS
VCM
Vo
Gm
Icomp
Vpwmi_h
Vpwmi_l
Vclamp_gate
Ts
Tf
Vovp_ov
Vth_fault
Tblanking_FB
Vin=12V, DIM=5V, no
load
8V<Vin<35V, ENA=0V,
disable mode, no load
Rising edge
8
ENA rising
ENA falling
2.8
RT=60k
RT=10k
1.6
Csync=1nF,10%-90%
Csync=1nF,10%-90%
35 V
3 5 mA
4 10 uA
6.8
6.5
1
100
1.2
V
V
V
V
k
V
100 kHz
600 kHz
V
1.2
350
250
V
ns
ns
570 600 630 mV
250 ns
85 90 95 %
13 V/s
0 3.5 V
1 4V
100 uA/V
65 uA
CGATE=2nF,10%-90%
CGATE=2nF,10%-90%
2V
1.8 V
11 V
80 ns
40 ns
Rising edge
2V
100 mV
500 ns
©On-Bright Electronics
Confidential
-5-
Preliminary Datasheet
OB_DOC_DS_337202