doc APL5537 Source and Sink, 2A, Fast Transient Response Linear Regulator

The APL5337 linear regulator is designed to provide a regulated voltage with bi-direction output current for DDRSDRAM termination voltage. The APL5337 integrates two power transistors to source or sink load current up to 2A. It also features internal soft-start, current-limit, thermal shutdown and enable control functions into a single chip.
The internal soft-start controls the rising rate of the output voltage to prevent inrush current during start-up. The current-limit circuit detects the output current and limits the current during short-circuit or current overload conditions. The on-chip thermal shutdown provides thermal protection against any combination of overload that would create excessive junction temperatures. The output voltage of APL5337 is regulated to track the voltage on VREF pin. A proper resistor divider connected to VIN, GND, and VREF pins is used to provide a half voltage of VIN to VREF pin. In addition, connect an external ceramic capacitor and an open-drain transistor to VREF pin for external soft-start and shutdown control.
Pulling and holding the voltage on VREF below the enable voltage threshold shuts down the output. The output of APL5337 will be high impedance after being shut down by VREF or the thermal shutdown function.