LT3437 High Voltage 500mA, 200kHz Step-Down Switching Regulator with 100A Quiescent Current FEATURES DESCRIPTIO Wide Input Range: 3.3V to 60V The LT 3437 is a 200kHz monolithic buck switching Load Dump (Input Transient) Protection to 80V regulator that accepts input voltages up to 80V. A high 500mA Peak Switch Current efficiency 500mA, 0.8 switch is included on the die along Burst Mode Operation: 100A Quiescent Current** with all the necessary oscillator, control and logic cir- Low Shutdown Current: I < 1A cuitry. Current mode topology is used for fast transient Q Defeatable Burst Mode Operation response and good loop stability. 200kHz Switching Frequency Innovative design techniques along with a new high volt- Saturating Switch Design: 0.8 On-Resistance age process achieve high efficiency over a wide input Peak Switch Current Maintained Over range. Efficiency is maintained over a wide output current Full Duty Cycle Range* range by employing Burst Mode operation at low currents, 1.25V Feedback Reference Voltage utilizing the output to bias the internal circuitry, and by Easily Synchronizable using a supply boost capacitor to fully saturate the power Soft-Start Capability switch. Burst Mode operation can be defeated by a logic Small 10-Pin Thermally Enhanced DFN Package high signal on the SYNC pin which results in lower light U load ripple at the expense of light load efficiency. Patented APPLICATIO S circuitry maintains peak switch current over the full duty High Voltage Power Conversion cycle range.* Shutdown reduces input supply current to 14V and 42V Automotive Systems less than 1A. External synchronization can be imple- Industrial Power Systems mented by driving the SYNC pin with logic-level inputs. A Distributed Power Systems single capacitor from the C pin to the output provides a SS Battery-Powered Systems controlled output voltage ramp (soft-start). Powered Ethernet The LT3437 is available in a low profile (0.75mm) 3mm , LT, LTC and LTM are registered trademarks of Linear Technology Corporation. Burst Mode 3mm 10-pin DFN package or a 16-Pin TSSOP Package, is a registered trademark of Linear Technology Corporation. All other trademarks are the property of their respective owners. *Protected by U.S. Patents, including 6498466. both with exposed pad leadframes for low thermal **See Burst Mode Operation section for conditions. resistance. TYPICAL APPLICATIO Input Voltage 14V to 3.3V Step-Down Converter with Supply Current vs Input Voltage Transient Response 100A No Load Quiescent Current 200 180 V OUT V IN V BOOST 3.3V IN 160 4.5V TO 80V* V 2.2F 100H 400mA IN 0.1F BAS21 SHDN 140 20V/DIV 100V SW CER LT3437 0.1F 120 10MQ100N V C C SS V 100 IN 1500pF 330pF 0V V BIAS 80 V 165k 27pF OUT 25k 100F 60 20mV/DIV SYNC FB 6.3V AC COUPLED 40 TANT 3437 TA03 I 250mA OUT 50ms/DIV GND 100k 20 LOAD DUMP COLD CRANK 0 3437 TA01 *FOR INPUT VOLTAGES ABOVE 60V RESTRICTIONS APPLY 0 10 20 30 40 50 60 70 80 INPUT VOLTAGE (V) 3437 TA02 3437fc 1 SUPPLY CURRENT (A) U ULT3437 ABSOLUTE AXI U RATI GS (Note 1) V , SHDN, BIAS, SW Operating ............................. 60V Operating Junction Temperature Range IN V , SHDN 100ms Transient, <15% Duty Cycle ....... 80V LT3437EDD (Note 2) ....................... 40C to 125C IN BOOST Pin Above SW ............................................ 35V LT3437IDD (Note 2) ........................ 40C to 125C BOOST Pin Voltage Operating................................. 75V LT3437EFE (Note 2) ........................ 40C to 125C BOOST Pin 100ms Transient, <15% Duty Cycle ...... 85V LT3437IFE (Note 2) ......................... 40C to 125C SYNC, C , FB .......................................................... 6V LT3437HFE (Note 2) .......................... 40C to 140C SS Storage Temperature Range ................. 65C to 125C DD Package ....................................... 65C to 125C FE Package ........................................ 65C to 150C UUW PACKAGE/ORDER I FOR ATIO TOP VIEW NC 1 16 NC TOP VIEW SW 2 15 SHDN NC 3 14 SYNC SW 1 10 SHDN V 4 13 NC IN V 2 9 SYNC IN 17 BOOST 3 11 8 FB NC 5 12 FB GND 4 7 V C BOOST 6 11 V C C 5 6 BIAS SS NC 7 10 BIAS GND 8 9 C SS DD PACKAGE 10-LEAD (3mm 3mm) PLASTIC DFN FE PACKAGE = 45C/W, = 10C/W 16-LEAD PLASTIC TSSOP JA JC(PAD) = 45C/W, = 10C/W EXPOSED PAD IS GND (PIN 11) JA JC(PAD) MUST BE SOLDERED TO GND (PIN 4) EXPOSED PAD IS GND (PIN 17) MUST BE SOLDERED TO GND (PIN 8) ORDER PART NUMBER DD PART MARKING ORDER PART NUMBER FE PART MARKING LT3437EDD LBDJ LT3437EFE 3437EFE LT3437IDD LBDK LT3437IFE 3437IFE LT3437HFE 3437HFE Order Options Tape and Reel: Add TR Lead Free: Add PBF Lead Free Tape and Reel: Add TRPBF Lead Free Part Marking: