LT3964 Dual 36V Synchronous 1.6A 2 Buck LED Driver with I C FEATURES DESCRIPTION n Wide Input Voltage Range: 4V to 36V The LT 3964 is a dual synchronous step-down DC/DC 2 n Two Independent 1.6A/40V Synchronous Bucks converter with 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 (8192:1), Analog Dimming and Fault Reporting for driving LEDs. The fixed frequency and peak current n 1000:1 External True Color PWM Dimming and mode topology result in stable operation over a wide range 10:1External Analog Dimming of supply and output voltages. The ground referred volt- n PMOS Switch Driver for PWM and Output Disconnect age FB pin serves as the input for several LED protection n 3% Constant Current Regulation features, and also allows the converter to operate as a n Adjustable Frequency: 200kHz to 2MHz constant-voltage source. The maximum output current is n Frequency Synchronization with Clock Output set by an external resistor, and the output current ampli- n Programmable OPENLED Protection with Reporting fier has a rail-to-rail common mode range. LT3964 uses 2 n Short-Circuit Protection with Reporting an I C interface to communicate with a microcontroller n Programmable Undervoltage Lockout with Hysteresis to read LED faults, write PWM and analog dimming reg- 2 n Internal Compensation isters and set fault masking. The I CPWM input provides 2 2 n 9 Unique Device Addresses for I C LED dimming ratios up to 8192:1. The I C programmable n Available in 5mm 6mm 36-Lead QFN Package CTRL register sets the gain of the external CTRL pin, and maximum current sense threshold, providing additional APPLICATIONS analog dimming capability. All registered trademarks and trademarks are the property of their respective owners. Protected n General Purpose, Industrial, Medical and by U.S. Patents, including 7199560, 7321203, 7746300. AutomotiveLighting n Constant-Current, Constant-Voltage Source TYPICAL APPLICATION 50W Dual Buck 1A LED Driver Efficiency, V = 34V IN IN 100 31V TO 36V V BST1 IN1 BOTH CHANNELS ARE ON 10F 0.22F (ENABLED AT 33V, 2.2F 10H 100m 2 SHUTDOWN 100k GND SW1 95 AT 31V) 2.2F EN/UVLO 1M 1A, 3.92k PWM1 PWM1 FB1 90 8 LEDs PWM2 PWM2 UP TO 43.2k CTRL1 26V CTRL2 INTV CC 85 INTV CC ISP1 100k 2.2F ISN1 ALERT PWMTG1 80 LT3964 V BST2 IN2 0.22F INTV 2.2F CC 75 10H 100m GND SW2 499k 2.2F 1M 70 T SET 1A, 100 200 300 400 500 600 700 800 900 1000 RT FB2 8 LEDs 165k 27.4k I (mA) LED 43.2k UP TO 2MHz 3964 TA01b 26V SYNC/CLKOUT ISP2 SCL 2-WIRE ISN2 2 SDA PWMTG2 I C INTERFACE ADDR1 ADDR2 3964 TA01a INTV CC 3964fb 1 For more information www.linear.com/LT3964 EFFICIENCY (%)LT3964 ABSOLUTE MAXIMUM RATINGS PIN CONFIGURATION (Note 1) V , V , EN/UVLO .................................................40V IN1 IN2 TOP VIEW ISP1, ISN1, ISP2, ISN2 ..............................................40V PWMTG1, PWMTG2, RT .......................................Note 2 SW1, SW2 .................................................................40V 36 35 34 33 32 31 30 29 RT 1 28 ISP1 BST1, BST2 ............................................................44.5V CTRL1 2 27 ISN1 BST1 to SW1, BST2 to SW2 ....................................4.5V CTRL2 3 26 PWMTG1 FB1, FB2, CTRL1, CTRL2, ADDR1, ADDR2 ..................5V EN/UVLO 4 25 SGND SYNC/CLKOUT, PWM1, PWM2, T ..........................6V SET INTV 5 24 FB1 CC 37 SDA, SCL, ALERT ........................................................6V PGND ALERT 6 23 FB2 INTV ..................................................................Note 3 CC PWM1 7 22 SGND Operating Junction Temperature (Notes 4, 5) PWM2 8 21 PWMTG2 SDA 9 20 ISN2 LT3964E/LT3964I .............................. 40C to 125C SCL 10 19 ISP2 LT3964H ............................................ 40C to 150C 11 12 13 14 15 16 17 18 Storage Temperature Range .................. 60C to 150C UHE PACKAGE 36-LEAD (5mm 6mm) PLASTIC QFN = 43C/W, = 5C/W JA JC EXPOSED PAD (PIN 37) IS PGND, MUST BE SOLDERED TO PCB