APE8903B Datasheet, PDF (6/10 Pages) Advanced Power Electronics Corp. – 3A ULTRA LOW DROPOUT LINEAR REGULATOR

Advanced Power
Electronics Corp.
APE8903B
FUNCTION DESCRIPTION
Under-Voltage Protection (UVP)
The APE8903B monitors the voltage on FB pin after soft-start process is finished. Therefore
the UVP is disabling during soft-start. When the voltage on FB pin falls below the under-voltage
threshold, the UVP circuit shuts off the output immediately. After a while, the APE8903B starts a
new soft-start to regulate output.
Thermal Shutdown
A thermal shutdown circuit limits the junction temperature of APE8903B. When the junction
temperature exceeds +160°C, a thermal sensor turns off the output NMOS, allowing the device to
cool down. The regulator regulates the output again through initiation of a new soft-start cycle after
the junction temperature cools by 40°C, resulting in a pulsed output during continuous thermal
overload conditions. The thermal shutdown designed.
APPLICATION INFORMATION
Capacitor Selection
Normally, use a MLCC capacitor on the input and output of the APE8903B. Larger input
capacitor values provide better supply-noise rejection and transient response. A higher- value
output capacitor may be necessary if large, fast transients are anticipated and the device is located
several inches from the power source. The X5R and X7R type in MLCC is recommended. For
aluminum electrolytic capacitor application, 100uF in input capacitor and 220uF in output capacitor
(30mΩ < ESR < 200mΩ) are recommended. Output capacitor of larger capacitance can reduce
noise and improve load transient response, stability, and PSRR.
6