A6300
AiT Semiconductor Inc.
www.ait-ic.com
LOW DROPOUT VOLTAGE REGULATOR
300mA CMOS WITH ENABLE PIN
Load-Transient Considerations
The A6300 Load-Transient response graphs (see Typical Characteristics) show two components of the output
response: a DC shift from the output impedance due to the load current change, and the transient response.
The DC shift is quite small due to excellent load regulation of the IC. Typical output voltage transient spike for
a step change in the load current from 1mA to 300mA is 20mV, depending on the ESR of the output capacitor.
Increasing the output capacitor’s value and decreasing the ESR attenuates the overshoot.
Shutdown Input Operation
The A6300 is shutdown by pulling the turned on by driving the input high. If this feature is not to be used, the
EN input should be tied to VIN to keep the regulator on at all times (the EN input must not be left floating).
To ensure proper operation, the signal source used to be drive the EN input must be able to swing above and
below the specified turn-on/turn-off voltage thresholds which guarantee and ON or OFF state. The ON/OFF
signal may come from either CMOS output, or an open-collector output with pull-up resistor to the A6300 input
voltage or another logic supply. The high-level voltage may exceed the A6300 input voltage, but must remain
within the absolute maximum rating for the EN pin.
Internal P-Channel Pass Transistor
The A6300 features a typical 0.75Ω P-Channel MOSFET pass transistor. It provides several advantages over
similar designs using PNP pass transistors, including longer battery life. The P-Channel MOSFET requires no
base drive, which reduces quiescent current considerably. PNP-based regulators waste considerable current
in dropout when the pass transistor saturates. They also use high base-drive currents under lager loads. The
A6300 does not suffer from these problems and consume only 80uA of quiescent current whether in dropout,
light-load, or heavy-load application.
Input-Output (Dropout) Voltage
A regulator’s minimum input-output voltage differential (or dropout voltage) determines the lowest usable
supply voltage. In battery-powered systems, this will determine the useful end-of-life battery voltage. Because
the A6300 uses a P-Channel MOSFET pass transistor, the dropout voltage is a function of drain-to-source
on-resistance RDS(ON) multiplied by the load current.
REV1.4
- JUN 2006 RELEASED, FEB 2015 UPDATED -
14
AITSEMI [ AiT Semiconductor ]
