AP3401

Document number: DS37389 Rev. 2 - 2

7 of 11

www.diodes.com

June 2016

© Diodes Incorporated

AP3401

Application Information

Typical application circuit is shown in the application circuit and for the circuit parameters setting please refers to the following descriptions.

Under Voltage Lockout (UVLO) Circuit

switch built-

higher than UVLO released voltage, the IC will restart the operation.

Short Circuit Protection and Recovery

AP3401 will enter cycle by cycle current limit mode until the current under OCP threshold.

Power Good

The PG pin output is an open drain MOSFET. The output is pulled low when the FB voltage enters the fault condition by falling below 80%or rising

above 120% of the nominal internal reference voltage. When the FB voltage rises to the good condition above 90% or falls below 110% of the

internal voltage reference PG output MOSET is turned off. It is recommended using a pull-up to VIN.

Over Temperature Protection

The internal thermal temperature protection circuitry is provided to protect the integrated circuit in the event that the maximum junction

temperature is exceeded. When the junction temperature exceeds +160°C, it shuts down the internal control circuit and switching power MOSFET.

The AP3401 will restart automatically under the control of soft start circuit when the junction temperature decreases to +145°C.

Input Over Voltage Protection

When input voltage of AP3401 is near 6.25V, the IC will enter Input-Over-Voltage-Protection. It would be shut down and there will be no output

voltage in this state. As the input voltage goes down below 6V, it will leave input OVP and recover the output voltage.

Setting the Output Voltage

The output voltage can be adjusted from 1 to 5V using an external resistor divider. Table 1 shows a list of resistor selections for common output

voltages. Resistor R1 is selected based on a design tradeoff between efficiency and output voltage accuracy. For high values of R1 there is less

current consumption in the feedback network. However the tradeoff is output voltage accuracy due to the bias current in the error amplifier. R1 can

be determined by the following equation. Meanwhile, the input capacitor should close to IC for preventing unexpected influences.

Figure 1. Feedback Divider Network

Table 1. Resistor Selection for Common Output

Out Voltage

R1

R2

C1

1.0V

91k

120k

22pf

1.2V

100k

100k

22pf

1.5V

150k

100k

22pf

1.8V

300k

150k

22pf

2.5V

380k

120k

22pf

2.8V

440k

120k

22pf

3.3V

430k

100k

22pf

LX

FB

R1

R2

C1