SC1578 Datasheet | SEMTECH

DESCRIPTION The SC1578 is a high performance step-down DC-DC converter, designed to drive an external P-channel MOSFET to generate programmable output voltages. Two main schemes of pulse-skipping and pulsefrequency modulation are employed to maintain low quiescent current and high conversion efficiency over wide ranges of input voltage and loads. The SC1578 delivers 10m A to 2A of output current with 87%-93% efficiency at VIN=9V, VOUT=5V. A current sense parator with both inverting and non-inverting inputs unmitted is included to provide the crucial function of either current limit protection or constant output current control. When the SC1578 is used in a highside current sensing step-down constant current source, the efficiency is typically greater than 90%. Duty cycle can be adjusted to greater than 90% by connecting a resistor from the DUTY pin to VIN. Quiescent current is about 90µA and can be reduced to 8µA in shutdown mode. With a switching frequency range of 90k Hz to 280k Hz, small size switching ponents may be used, which is ideal for battery powered portable equipment. Features - 4V to 24V input voltage operation. - High efficiency (up to 95%). - Low quiescent current at 90µA. - Pulse-skipping and pulse-frequency modulation. - Inputs-unmitted current sense parator. - Duty cycle adjustable - 90k Hz to 280k Hz oscillator frequency - Power-saving shutdown mode (8µA Typical). - Push-pull driver output APPLICATIONS - Notebook 5V/3.3V main power - Step-down DC-DC converter module. - Constant current source for battery chargers. BLOCK DIAGRAM ORDERING INFORMATION DEVICE (1) PACKAGE SO-8 SC1578CS Note: (1) Add suffix ‘TR’ for tape and reel. PIN CONFIGURATION ABSOLUTE MAXIMUM RATINGS Parameter Supply Voltage Duty Voltage SHDN Voltage Operating Temperature Range Storage Temperature Range Symbol VIN VDUTY VSHDN TA TSTG Maximum 24 20 15 0 to 70 -65 to 150 Units V V V °C °C © 1997 SEMTECH CORP. 652 MITCHELL ROAD NEWBURY PARK CA 91320 HIGH-EFFICIENCY STEP-DOWN...