AP7348

Document number: DS42124 Rev. 3 - 2

10 of 15

www.diodes.com

August 2020

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AP7348

Application Information

Output Capacitor

An output capacitor (COUT) is needed to improve transient response and maintain stability. The AP7348 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 ground

pin 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 4.7μF ceramic

capacitor is recommended between VDD 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 VDD and GND pins.

Enable Control

The AP7348 is turned on by setting the EN pin high, and is turned off by pulling it low. When EN1 (EN2) pin pull high, the CH1 and CH3 (CH2 and

CH4) are turned on at the same time. If this feature is not used, the EN pins should be tied to VDD pin to keep the regulator output on at all times.

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 pin is short-circuit to GND, short circuit protection will be triggered and clamp the output current to approximately 55mA. This feature

protects the regulator from overcurrent 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 ground pins of the device. The

regulator ground pin 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.

0

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40

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ESR vs. Output Current

Output Current IOUT (mA)