L1913

Preliminary

CMOS IC

UNISONICTECHNOLOGIESCO.,LTD

8 of 9

www.unisonic.com.tw

QW-R502-439.b

APPLICATIONS INFORMATION

Capacitor Selection and Regulator Stability

A 1µF capacitor on the input and a 1µF capacitor on the output are recommended for most applications of the U

TC L1913. To get a better supply-noise rejection and transient response, input capacitors with larger values and

lower ESR are needed. A higher-value input capacitor (10µF) may be necessary if large, fast transients are

anticipated and the device is located several inches from the power source.

Power-Supply Rejection and Operation from Sources Other than Batteries

The UTC L1913 is particularly designed to deliver low dropout voltages and low quiescent currents in battery-

powered systems. Power-supply rejection is 42dB at low frequencies. As the frequency increases above 20kHz, the

output capacitor is the major contributor to the rejection of power-supply noise.

When operating from sources other than batteries, improve supply-noise rejection and transient response by

increasing the values of the input and output capacitors, and using passive filtering techniques.

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 UTC

L1913

current.