SYNCHRONOUS_STEPDOWN_SWITCHING_REGULATOR_WITH_90％EFFICIENCY

Published:2009/6/26 5:01:00 Author:May | From:SeekIC

A shows a typical LTC1148 surface-mount application providing 5 V at 2 A from an input voltage of 5.5 V to 13.5 V. The operating efficiency, shown in B, peaks at 97% and exceeds 90% from 10 mA to 2 A with a 10-V input. Q1 and Q2 comprise the main switch and synchronous switch, respectively, and inductor current is measured via the voltage drop across the current shunt. RSENSE is the key component used to set the output current capability according to the formuta IOUT = 100 mV/RSENSE. The advantages of current control include excellent line and load transient rejection, inherent shortcircuit protection and controlled startup currents. Peak inductor current is limited to 150 mV/RSENSE or 3 A for the circuit in A.



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