LT3964-1
Dual 36V Synchronous 2A
2
Buck LED Driver with I C
FEATURES
DESCRIPTION
The LT®3964-1 is a dual synchronous step-down DC/DC
n
Wide Input Voltage Range: 4V to 36V
2
n
Two Independent 2A/40V Synchronous Bucks
converter with an I C interface designed to operate as a
2
n
I C Interface for Internal True Color PWM™ Dimming
constant-current and constant-voltage source and is ideal
for driving LEDs. The fixed frequency and peak current
mode topology result in stable operation over a wide range
of supply and output voltages. The ground-referred volt-
age FB pin serves as the input for several Light Emitting
Diode (LED) protection features, and allows the converter
to operate as a constant-voltage source. The maximum
output current is set by an external resistor, and the output
current amplifier has a rail-to-rail common mode range.
(8192:1), Analog Dimming and Fault Reporting
n
1000:1 External True Color PWM Dimming and
10:1 External Analog Dimming
n
P-Channel Metal-Oxide Semiconductor (PMOS)
Switch Driver for Pulse-Width Modulators (PWM)
and Output Disconnect
n
3% Constant Current Regulation
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Adjustable Frequency: 200kHz to 2MHz
2
n
Frequency Synchronization with Clock Output
LT3964-1 uses an I C interface to communicate with a
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Programmable OPENLED Protection with Reporting
microcontroller to read LED faults, write PWM and analog
2
n
Short-Circuit Protection with Reporting
dimming registers and set fault masking. The I C PWM
2
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Programmable Undervoltage Lockout with Hysteresis
input provides LED dimming ratios up to 8192:1. The I C
n
Internal Compensation
9 Unique Device Addresses for I C
programmable CTRL register sets the gain of the external
CTRL pin, and maximum current sense threshold, provid-
ing additional analog dimming capability.
2
n
n
Available in 5mm × 6mm 36-pin Quad-flat no-leads
(QFN) Package
All registered trademarks and trademarks are the property of their respective owners. Protected
by U.S. Patents, including 7199560, 7321203, 7746300.
APPLICATIONS
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General Purpose, Industrial, Medical
and Automotive Lighting
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Constant-Current, Constant-Voltage Source
TYPICAL APPLICATION
50W Dual Buck 1A LED Driver
Efficiency, VIN = 34V
100
BST1
BOTH CHANNELS ARE ON
0.22µF
31V TO 36V
(ENABLED
AT 33V,
V
IN1
10µH
100mΩ
10µF
×2
2.2µF
95
SW1
GND
100k
1M
2.2µF
SHUT-
DOWN
AT 31V)
EN/UVLO
FB1
1A,
90
85
80
75
70
PWM1 PWM1
PWM2 PWM2
CTRL1
3.92k
43.2k
8 LEDs
UP TO
26V
CTRL2
INTV
CC
ISP1
ISN1
PWMTG1
INTV
CC
2.2µF
100k
ALERT
IN2
BST2
SW2
FB2
LT3964-1
V
0.22µF
INTV
CC
2.2µF
10µH
100mΩ
GND
499k
2.2µF
1M
T
SET
RT
1A,
165k
100 200 300 400 500 600 700 800 900 1000
8 LEDs
UP TO
26V
43.2k
27.4k
2MHz
I
(mA)
LED
39641 TA01b
SYNC/CLKOUT
ISP2
ISN2
PWMTG2
SCL
SDA
2-WIRE
I C INTERFACE
2
ADDR1 ADDR2
39641 TA01a
INTV
CC
Rev. 0
1
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