LT3745IUJ#PBF

LT3745 16-Channel 50mA LED Driver with Buck Controller Features Description 6V to 55V Power Input Voltage Range 16 Independent LED Outputs Up to 75mA/36V ±3% LED Current Matching at 50mA (Typ ±1%) 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 n 40-Lead 6mm × 6mm QFN Package The LT®3745 integrates a 16-channel LED driver with a 55V buck controller. The LED driver lights up to 75mA/36V 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. A ±3% LED current matching and a 0.5µs minimum LED on-time can be achieved at 50mA per channel. n n n n n n n n n Applications Large Screen Display LED Backlighting Mono-, Multi-, Full-Color LED Displays n LED Billboards and Signboards n n L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and True Color PWM is a trademark of Linear Technology Corporation. All other trademarks are the property of their respective owners. The LT3745 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. Typical Application 16-Channel LED Driver, 1MHz Buck, 10 LEDs, 25mA to 75mA per Channel, 500Hz 12-Bit Dimming VIN 42V TO 55V 0.47µF VIN EN VCC 3V TO 5.5V EN/UVLO CAP GATE 47µH 100k VCC 10µF SS GND LT3745 10nF 2.048MHz CLOCK 10k ISN .. .. . FB ISET 60.4k C1 2 × 47µF ISP TSET 32.4k . .. RT 25mΩ 267k SYNC 46.4k 4.7µF LED00 .. .. . .. .. . .. .. . .. .. . .. .. . LED01 LED02 PWMCK .. . LED13 LED14 LED15 TTL/CMOS 3745 TA01 SCKI SCKO SDI SDO LDI LDO TTL/CMOS 3745f 1 LT3745 Absolute Maximum Ratings Pin Configuration (Note 1) RT SS FB ISN ISP CAP GATE VIN TSET ISET TOP VIEW 40 39 38 37 36 35 34 33 32 31 EN/UVLO 1 30 SYNC LED07 2 29 LED08 LED06 3 28 LED09 LED05 4 27 LED10 41 GND LED04 5 LED03 6 26 LED11 25 LED12 LED02 7 24 LED13 LED01 8 23 LED14 LED00 9 22 LED15 GND 10 21 GND SCKO GND SDO LDO PWMCK VCC LDI SDI GND 11 12 13 14 15 16 17 18 19 20 SCKI VIN ........................................................................... 57V CAP.......................................................... VIN – 8V to VIN GATE...............................................................CAP to VIN LED00 to LED15, ISP, ISN..........................................40V 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) LT3745E.............................................–40°C to 125°C LT3745I..............................................–40°C to 125°C Storage Temperature Range...................–65°C to 125°C UJ PACKAGE 40-LEAD (6mm × 6mm) PLASTIC QFN TJMAX = 125°C, θJA = 34°C/W, θJC = 2.5°C/W EXPOSED PAD (PIN 41) IS GND, MUST BE SOLDERED TO PCB Order Information LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE LT3745EUJ#PBF LT3745EUJ#TRPBF 3745 40-Lead (6mm × 6mm) Plastic QFN –40°C to 125°C LT3745IUJ#PBF LT3745IUJ#TRPBF 3745 40-Lead (6mm × 6mm) Plastic QFN –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 nonstandard 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/ 3745f 2 LT3745 Electrical Characteristics The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VIN = 12V, VCC = 3.3V, VEN/UVLO = 1.5V, VFB = 1.5V, VISP = VISN = 0V, RT = 105k, RISET = 60.4k, CCAP = 0.47µF to VIN, unless otherwise noted. SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS Supply VIN VIN Operating Voltage IVIN VIN Supply Current VCC VCC Operating Voltage IVCC VCC Supply Current (Note 4) l 6 VEN/UVLO = 0V No Switching 55 0.2 0.4 l 3 VEN/UVLO = 0V LED Channel Off, 30MHz Data Off LED Channel On, 30MHz Data Off LED Channel On, 30MHz Data On 2 0.55 V µA mA 5.5 V 0.1 3.1 7 16 1 3.6 µA mA mA mA Undervoltage Lockout (UVLO) IEN/UVLO VCC UVLO Threshold VCC Rising VCC Falling 2.82 2.61 2.89 2.68 2.96 2.75 V V EN/UVLO Shutdown Threshold UVLO Threshold IVCC