AP7332

DUAL 300mA LOW QUIESCENT CURRENT FAST

TRANSIENT LOW DROPOUT LINEAR REGULATOR

AP7332

Document number: DS35132 Rev. 1 - 2

12 of 18

www.diodes.com

December 2010

© Diodes Incorporated

Application Note

Input Capacitor

A 1

μF ceramic capacitor is recommended between IN and GND pins to decouple input power supply glitch and noise. The

amount of the capacitance may be increased without limit. This input capacitor must be located as close as possible to the

device to assure input stability and reduce noise. For PCB layout, a wide copper trace is required for both IN and GND pins.

A lower ESR capacitor type allows the use of less capacitance, while higher ESR type requires more capacitance.

Output Capacitor

The output capacitor is required to stabilize and improve the transient response of the LDO. The AP7332 is stable with very

small ceramic output capacitors. Using a ceramic capacitor value that is at least 1

μF with ESR

≧10mΩ on the output ensures

stability. Higher capacitance values help to improve line and load transient response. The output capacitance may be

increased to keep low undershoot and overshoot. Output capacitor must be placed as close as possible to OUT and GND

pins.

0.001

0.01

0.1

1

10

100

0

20

50

100

150

200

250

300

Load Current (mA)

No Load Stability

Other than external resistor divider, no minimum load is required to keep the device stable. The device will remain stable and

regulated in no load condition.

ON/OFF Input Operation

The AP7332 is turned on by setting the EN pin high, and is turned off by pulling it low. If this feature is not used, the EN pin

should be tied to IN pin to keep the regulator output on at all time. To ensure proper operation, the signal source used to drive

the EN pin must be able to swing above and below the specified turn-on/off voltage thresholds listed in the Electrical

Unstable Range

Stable Range

Unstable Range