DESCRIPTION
SC1531(A) FEATURES
Glitch-free transition between input sources Internal logic selects input source Gate drive for external PMOS bypass switch 5V detection with hysteresis 1% regulated output voltage accuracy 200mA load current capability (250mA for SC1531A) Remote sense SO-8 package u u u u Whenever VIN exceeds a predetermined threshold value, u the internal 3.3V linear regulator is enabled, and DR is u pulled high. u When VIN falls below a lower threshold value, DR is pulled u low and the internal linear regulator is turned off. DR has been designed to drive the gate of an external low threshold P-channel MOSFET, which can be used to connect the 3.3V supply directly to the regulator output. A typical RDS(ON) of 400mW is recommended (320mW for SC1531A). When both supplies are simultaneously available, the drive pin (DR) will be pulled High, turning off the external PMOS switch. The internal 5V detector has its upper threshold (for VIN rising) set to 4.18V (typical) while the lower threshold (for VIN falling) is at 4.05V (typical) giving a hysteresis of approximately 130mV.
Semtech Corporation
