AP2127

Document number: DS36478 Rev. 7 - 2

13 of 24

www.diodes.com

December 2017

© Diodes Incorporated

AP2127

Application Notes (Cont.)

1µF

4.7µF

VIN

R1

VOUT

ADJ

R2

GND

Shutdown

Cf

AP2127

Figure 1. Application Circuit with Feed-forward Capacitor

Current Limit Protection

When output current at V

OUT pin is higher than current limit threshold, the current limit protection will be triggered and clamp the output current to

prevent over-current and to protect the regulator and load from damaged due to overheating.

Short Circuit Protection

When VOUT pin is shorted to GND, short circuit protection will be triggered and clamp the output current to approximately 50mA.

Auto discharge with Shutdown Version

For shutdown version, an auto discharge MOSFET with RDS(ON) of 60Ω typical is integrated between VOUT and GND pins, which can discharge

the charge of the output capacitors quickly when turning off AP2127 with Shutdown pin.

Thermal Consideration

Internal thermal protection circuitry of AP2127 is used to protect device during overload conditions. For continuous operation, ensure not to

exceed the operating junction temperature range of +125°C.

The power dissipation definition in the device is:

PD = (VIN - VOUT) x IOUT + VIN x IQ

The maximum power dissipation depends on the thermal resistance of IC package, PCB layout and the surrounding airflow. The maximum power

dissipation can also be calculated as:

PD(MAX) = (TJ(MAX) - TA) / θJA

The maximum power dissipation for SOT-23-5 package (least copper size) at TA = +25°C can be calculated as:

PD(MAX) = (125°C - 25°C) / (250°C/W) = 0.4W