AP7345D

Document number: DS41528 Rev. 1 - 2

10 of 15

www.diodes.com

December 2018

© Diodes Incorporated

AP7345D

Application Information

Output Capacitor

An output capacitor (COUT) is needed to improve transient response and maintain stability. The AP7345D is stable with very small ceramic output

capacitors. The ESR (Equivalent Series Resistance) and capacitance drives the selection. If the application has large load variations, it is

recommended to utilize low-ESR bulk capacitors. It is recommended to place ceramic capacitors as close as possible to the load and the GND pins

and care should be taken to reduce the impedance in the layout.

Input Capacitor

To prevent the input voltage from dropping during load steps, it is recommended to utilize an input capacitor (CIN). A minimum 1μF ceramic

capacitor is recommended between VIN and GND pins to decouple input power supply glitch. 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 VIN and GND pins.

Enable Control

The AP7345D is turned on by setting the EN pins high, and is turned off by pulling it low. If this feature is not used, the EN pins should be tied to VIN

pins to keep the regulator output on at all time. To ensure proper operation, the signal source used to drive the EN pins must be able to swing

above and below the specified turn-on/off voltage thresholds listed in the Electrical Characteristics section.

Short Circuit Protection

When VOUT pins are short-circuit to GND, short circuit protection will be triggered and clamp the output current to approximately 60mA. This feature

protects the regulator from over-current and damage due to overheating.

Layout Considerations

For good ground loop and stability, the input and output capacitors should be located close to the input, output, and GND pins of the device. The

regulator GND pins should be connected to the external circuit ground to reduce voltage drop caused by trace impedance. Ground plane is

generally used to reduce trace impedance. Wide trace should be used for large current paths from VIN to VOUT, and load circuit.

ESR vs. Output Current

Ceramic type output capacitor is recommended for this series; however, the other output capacitors with low ESR also can be used. The relations

between IOUT (Output Current) and ESR of an output capacitor are shown below. The stable region is marked as the hatched area in the graph.

Measurement conditions: Frequency Band: 10Hz to 2MHz, Temperature: -40°C to +85°C.