AP22815 / AP22615

Document number: DS41022 Rev. 5 - 2

13 of 17

www.diodes.com

August 2019

© Diodes Incorporated

AP22815 / AP22615

Application Information (continued)

ON/OFF Input Operator

The EN input allows the output current to be switched on and off using a GPIO compatible input. The high signal (switch on) must be at least 1.2V

and the low signal (switch off) no higher than 0.4V. This pin should not be left floating. It is advisable to hold the EN signal low when applying or

removing power.

Undervoltage Lockout (UVLO)

Undervoltage lockout function (UVLO) keeps the internal power switch from being turned on until the power supply has reached at least 2.5V,

even if the switch is enabled. Whenever the input voltage falls below approximately 2.3V, the power switch is quickly turned off. This facilitates the

design of hot-insertion systems where it is not possible to turn off the power switch before input power is removed.

Discharge Function

The discharge function of the device is active when enable is disabled or de-asserted. The discharge function with the N-MOS power switch

implementation is activated and offers a resistive discharge path for the external storage capacitor. This is designed for discharging any residue of

the output voltage when either no external output resistance or load resistance is present at the output.

Output Reverse-Voltage/Current Protection

The output reverse-voltage protection turns off the MOSFET switch whenever the output voltage is higher than the input voltage by 65mV, and the

MOSFET switch turns on when output reverse-voltage conditions is removed. When reverse-voltage is lower than 65mV, the reverse current is

regulated at approximately 350mA. When the reverse current continuously increases and the reverse voltage is larger than 65mV, the reverse-

voltage protection is triggered.

Fast Role-Swap Function

The AP22615 & AP22815 integrate the fast role-swap function, which makes VOUT recovery to 4.75V within 150μs during VOUT drops from high

voltage to low. When EN is high, VIN is valid, and VOUT is higher than VIN by 65 mV, the device works at reverse block mode, power FET is off and

standby for FRS. Once VOUT drops lower than VIN, power FET is turned on in 150μs.

Power Dissipation and Junction Temperature

The low on-resistance of the internal MOSFET allows the small surface-mount packages to pass large current. Using the maximum operating

ambient temperature (TA) and RDS(ON), the power dissipation can be calculated by:

PD = RDS(ON) × I

2

Finally, calculate the junction temperature:

TJ = PD × RϴJA + TA

Where:



TA = Ambient temperature °C



RϴJA = Thermal resistance



PD = Total power dissipation

Board Layout Instruction

Placing input and output capacitors, 1

μF and 0.1μF+100μF respectively, close and next to the device pins must be implemented to minimize the

effects of parasitic inductance. For best performance, all trace lengths must be kept as short as possible. The input and output PCB traces must

be as wide as possible. Use a ground plane to enhance the power dissipation capability of the device.