LT3476

LT3746 32-Channel 20mA LED Driver with Buck Controller FeaTures n n n n n n n n DescripTion The LT®3746 integrates a 32-channel LED driver with a 55V buck controller. The LED driver lights up to 30mA/13V of LEDs in series per channel, and the buck controller generates an adaptive bus voltage supplying the parallel LED strings. Each channel has individual 6-bit dot correction current adjustment and 12-bit grayscale PWM dimming. Both dot correction and grayscale are accessible via a serial data interface in TTL/CMOS logic. The LT3746 performs full diagnostic and protection against open/short LED and overtemperature fault. The fault status is sent back through the serial data interface. The 30MHz fully-buffered, skew-balanced, cascadable serial data interface makes the chip extremely suitable for large screen LCD dynamic backlighting and mono-, multi-, full-color LED displays. 6V to 55V Power Input Voltage Range 32 Independent LED Outputs up to 30mA/13V 6-Bit Dot Correction Current Adjustment 12-Bit Grayscale PWM Dimming 0.5µs Minimum LED On Time Adaptive LED Bus Voltage for High Efficiency Cascadable 30MHz Serial Data Interface Full Diagnostic and Protection: Individual Open/Short LED and Overtemperature Fault applicaTions n n n Large Screen Display LED Backlighting Mono-, Multi-, Full-Color LED Displays LED Billboards and Signboards L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. Typical applicaTion 32-Channel LED Driver, 1MHz Buck, 3 LEDs 10mA to 30mA per Channel, 500Hz 12-Bit Dimming VIN 13V TO 42V VIN EN VCC 3V TO 5.5V 10µF 100k VCC SYNC RT 46.4k SS 10nF ISET 60.4k TSET 32.4k GND LT3746 ISP ISN FB LED00 LED01 LED02 PWMCK LED29 LED30 LED31 SCKI TTL/CMOS SDI LDI SCKO SDO LDO 3746 TA01 0.47µF EN/UVLO CAP GATE 4.7µF 22µH 33m 80.6k C1 2 × 47µF . . . 10k 2.048MHz CLOCK . . . TTL/CMOS 3746f 1 LT3746 absoluTe MaxiMuM raTings (Note 1) pin conFiguraTion TOP VIEW GATE TSET CAP ISET ISN ISP VIN SS GND RT 46 SYNC 45 LED16 44 LED17 43 LED18 42 LED19 41 LED20 40 LED21 39 LED22 57 GND 38 LED23 37 LED24 36 LED25 35 LED26 34 LED27 33 LED28 32 LED29 31 LED30 30 LED31 29 GND 19 20 21 22 23 24 25 26 27 28 LDO PWMCK SDO SCKO GND SDI SCKI LDI VCC FB VIN .......................................................................... 57V CAP ......................................................... VIN – 8V to VIN GATE ..............................................................CAP to VIN LED00 to LED31, ISP, ISN ......................................... 13V ISP .................................................ISN – 1V to ISN + 1V FB, RT, TSET, ISET ....................................................... 2V VCC ...............................................................–0.3V to 6V SCKI, SCKO, SDI, SDO, LDI, LDO, PWMCK, SYNC, SS, EN/UVLO ............................................. –0.3V to VCC Operating Junction Temperature Range (Notes 2, 3)............................................–40°C to 125°C Storage Temperature Range ..................–65°C to 125°C 56 55 54 53 52 51 50 49 48 47 EN/UVLO 1 LED15 2 LED14 3 LED13 4 LED12 5 LED11 6 LED10 7 LED09 8 LED08 9 LED07 10 LED06 11 LED05 12 LED04 13 LED03 14 LED02 15 LED01 16 LED00 17 GND 18 UHH PACKAGE 56-LEAD (5mm × 9mm) PLASTIC QFN TJMAX = 125°C, θJA = 32°C/W, θJC = 2.0°C/W EXPOSED PAD (PIN 57) IS GND, MUST BE SOLDERED TO PCB orDer inForMaTion LEAD FREE FINISH LT3746EUHH#PBF LT3746IUHH#PBF TAPE AND REEL LT3746EUHH#TRPBF LT3746IUHH#TRPBF PART MARKING* 3746 3746 PACKAGE DESCRIPTION 56-Lead (5mm × 9mm) Plastic QFN 56-Lead (5mm × 9mm) Plastic QFN TEMPERATURE RANGE –40°C to 125°C –40°C to 125°C Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container. 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/ 3746f 2 LT3746 elecTrical characTerisTics SYMBOL Supply VIN IVIN VCC IVCC VIN Operating Voltage VIN Supply Current VCC Operating Voltage VCC Supply Current (Note 4) VEN/UVLO = 0V LED Channel Off, 30MHz Data Off LED Channel On, 30MHz Data Off LED Channel On, 30MHz Data On VCC Rising VCC Falling IVCC