POWER LOSS (W) LT1976/LT1976B High Voltage 1.5A, 200kHz Step-Down Switching Regulator with 100A Quiescent Current FEATURES DESCRIPTIO The LT 1976/LT1976B are 200kHz monolithic step-down Wide Input Range: 3.3V to 60V switching regulators that accept input voltages up to 60V. 1.5A Peak Switch Current (LT1976) A high efficiency 1.5A, 0.2 switch is included on the die 100A Quiescent Current (LT1976)** along with all the necessary oscillator, control and logic 1.6mA Quiescent Current (LT1976B) circuitry. Current mode topology is used for fast transient Low Shutdown Current: I < 1A Q response and good loop stability. Power Good Flag with Programmable Threshold Load Dump Protection to 60V Innovative design techniques along with a new high volt- 200kHz Switching Frequency age process achieve high efficiency over a wide input Saturating Switch Design: 0.2 On-Resistance range. Efficiency is maintained over a wide output current Peak Switch Current Maintained Over range by employing Burst Mode operation at low currents, Full Duty Cycle Range* utilizing the output to bias the internal circuitry, and by 1.25V Feedback Reference Voltage using a supply boost capacitor to fully saturate the power Easily Synchronizable switch. The LT1976B does not shift into Burst Mode Soft-Start Capability operation at low currents, eliminating low frequency out- Small 16-Pin Thermally Enhanced TSSOP Package put ripple at the expense of efficiency. Patented circuitry U maintains peak switch current over the full duty cycle APPLICATIO S range.* Shutdown reduces input supply current to less High Voltage Power Conversion than 1A. External synchronization can be implemented 14V and 42V Automotive Systems by driving the SYNC pin with logic-level inputs. A single Industrial Power Systems capacitor from the C pin to the output provides a SS Distributed Power Systems controlled output voltage ramp (soft-start). The devices Battery-Powered Systems also have a power good flag with a programmable thresh- old and time-out and thermal shutdown protection. , LT, LTC and LTM are registered trademarks of Linear Technology Corporation. Burst Mode is a registered trademark of Linear Technology Corporation. All other trademarks are the property of their respective owners. The LT1976/LT1976B are available in a 16-pin TSSOP *Protected by U.S. Patents, including 6498466 package with Exposed Pad leadframe for low thermal **See Burst Mode Operation section for conditions resistance. TYPICAL APPLICATIO LT1976 Supply Current vs LT1976 Efficiency and Power 14V to 3.3V Step-Down Converter with Input Voltage Loss vs Load Current 100A No Load Quiescent Current 150 100 10 V = 3.3V OUT T = 25C A EFFICIENCY V OUT 125 V IN V BOOST 3.3V IN 3.3V TO 60V 75 1 4.7F 33H 1A 0.33F 4148 SHDN 100V SW 100 5V CER LT1976 0.1F 3.3V 10MQ60N 75 50 0.1 V C SS C 330pF 1500pF TYPICAL V BIAS 165k 50 POWER LOSS 47pF FB 1% 10k 100F C 25 0.01 T 6.3V PGFB 1F SYNC 25 TANT 100k GND PG 1% 0 0 0.001 1976 TA01 0 10 20 30 40 50 60 0.1 1 10 100 1000 10000 INPUT VOLTAGE (V) 1976 F05 LOAD CURRENT (mA) 1976 TA02 1976bfg 1 SUPPLY CURRENT (A) EFFICIENCY (%) U ULT1976/LT1976B UUW ABSOLUTE AXI U RATI GS PACKAGE/ORDER I FOR ATIO (Note 1) V , SHDN, PG, BIAS .............................................. 60V ORDER PART IN TOP VIEW BOOST Pin Above SW ............................................ 35V NUMBER NC 1 16 PG BOOST Pin Voltage ................................................. 68V LT1976EFE SW 2 15 SHDN SYNC, C , PGFB, FB................................................ 6V SS LT1976IFE NC 3 14 SYNC Operating JunctionTemperature Range LT1976HFE V 4 13 PGFB IN LT1976EFE/LT1976BEFE (Note 2) ... 40C to 125C 17 LT1976BEFE NC 5 12 FB LT1976IFE/LT1976BIFE (Note 2) ..... 40C to 125C LT1976BIFE BOOST 6 11 V C LT1976HFE (Note 2) ........................ 40C to 140C C 7 10 BIAS T FE PART MARKING Storage Temperature Range ................. 65C to 150C GND 8 9 C SS 1976EFE Lead Temperature (Soldering, 10 sec).................. 300C FE PACKAGE 1976IFE 16-LEAD PLASTIC TSSOP = 45C/W, = 10C/W JA JC(PAD) 1976HFE EXPOSED PAD IS GND (PIN 17) 1976BEFE MUST BE SOLDERED TO GND (PIN 8) 1976BIFE Order Options Tape and Reel: Add TR Lead Free: Add PBF Lead Free Tape and Reel: Add TRPBF Lead Free Part Marking: