LT1432-3.3 Datasheet | Linear Technology

LT1432-3.3 3.3V High Efficiency Step-Down Switching Regulator Controller Features s s s s s s s s DESCRIPTIO Accurate Preset 3.3V Output Up to 87% Efficiency Optional Burst Mode TM Operation for Light Loads Can Be Used with Many LTC Switching ICs Accurate Ultra-Low-Loss Current Limit Operates with Inputs from 4.5V to 30V Shutdown Mode Draws Only 15µA Uses Small 30µH Inductor The LT ®1432-3.3 is a control chip designed to operate with the LT1171/LT1271 family of switching regulators to make a very high efficiency 3.3V step-down (buck) switching regulator. A minimum of external ponents is needed. Included is an accurate current limit which uses only 60m V sense voltage and uses “free” PC board trace material for the sense resistor. Logic controlled electronic shutdown mode draws only 15µA battery current. The switching regulator operates down to 4.5V input. The LT1432-3.3 has a logic controlled Burst Mode operation to achieve high efficiency at very light load currents (0m A to 100m A) such as memory keep-alive. In normal switching mode, the standby power loss is about 30m W, limiting efficiency at light loads. In Burst Mode operation, standby loss is reduced to approximately 11m W. Output current in this mode is typically in the 5m A to 100m A range. The LT1432-3.3 is available in 8-pin SO and PDIP packages. The LT1171/LT1271 is also available in surface mount DD packages. APPLICATI s s Laptop and Palmtop puters Portable Data-Gathering Instruments , LTC and LT are registered trademarks of Linear Technology Corporation. Burst Mode is a trademark of Linear Technology Corporation. TYPICAL APPLICATI D2 1N5818 VIN + VSW C1 330µF 35V C6 0.02µF C5† 0.03µF D1 MBR330p LT1271 FB VC 10µH 3A 100µF 16V + D2- - OPTIONAL OUTPUT FILTER + VC VIN LT1432-3.3 DIODE V+ VLIM VOUT GND × C2 390µF 16V VOUT- - - 3.3V 3A EFFICIENCY (%) C3 10µF TANT + L1 30µH R2- 0.013Ω MODE LOGIC 220p F MODE <0.3V = NORMAL MODE >2.5V = SHUTDOWN OPEN = Burst Mode...