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AS1375

Datasheet - A p p l i c a t i o n I n f o r m a t i o n

9 Application Information

Capacitor Selection and Regulator Stability

For normal operation, use a 1µF capacitor at pin IN and a 1µF capacitor at pin OUT. Larger input capacitor values and

lower ESR provide better noise rejection and line-transient response. Reduce output noise and improve load-transient

response, stability, and power-supply rejection by using large output capacitors.

Note: Some ceramic dielectrics exhibit large capacitance and ESR variation with temperature. With dielectrics such

as Z5U and Y5V, it may be necessary to use a 2.2µF or larger output capacitor to ensure stability at tempera-

tures below -10°C. With X7R or X5R dielectrics, 1µF is sufficient at all operating temperatures.

Noise, PSRR, and Transient Response

The AS1375 is designed to deliver low dropout and low quiescent currents in battery-powered systems. The power-

supply rejection is 85dB at 1kHz and 50dB at 100kHz.

When operating from sources other than batteries, improved supply-noise rejection and transient response can be

achieved by increasing the values of the input and output capacitors, and through passive filtering techniques.

Dropout Voltage

The AS1375 minimum dropout voltage determines the lowest usable supply voltage. In battery-powered systems, this

determines the useful end-of-life battery voltage.

Since the AS1375 use a P-channel MOSFET pass transistor, the dropout voltage is a function of drain-to-source on-