AP7344 Datasheet, PDF (10/15 Pages) Diodes Incorporated – DUAL 300mA HIGH PSRR LOW NOISE LDO WITH ENABLE

Performance Characteristics (Cont.)
Turn Off Waveforms
VOUT=1.8V
2
1
0
0
EN Input Voltage
3
2
1
0
IOUT=0mA
Output Voltage I_OUT=30mA
IOUT=300mA
40
80
120
160
200
Time t (µs)
AP7344
Turn Off Waveforms
VOUT=2.8V
4
2
0
0
EN Input Voltage
4
2
0
IOUT=0mA
Output Voltage IOUT=30mA
IOUT=300mA
40
80
120
160
200
Time t (µs)
Application Information
Output Capacitor
An output capacitor (COUT) is needed to improve transient response and maintain stability. The AP7344 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 0.47μF 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 AP7344 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.
AP7344
Document number: DS37368 Rev. 1 - 2
10 of 15
www.diodes.com
January 2015
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