AP61300/AP61302

Document number: DS43404 Rev. 3 - 2

14 of 21

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November 2022

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AP61300/AP61302

Application Information (continued)

3

Enable

When disabled, the device shutdown supply current is only 0.1

μA. When applying a voltage greater than the EN logic high threshold (typical 0.91V,

rising), the AP61300/AP61302 enables all functions and the device initiates the soft-start phase. The AP61300/AP61302 has a built-in 0.5ms soft-

start time to prevent output voltage overshoot and inrush current. When the EN voltage falls below its logic low threshold (typical 0.83V, falling),

the internal SS voltage discharges to ground and device operation disables.

The device operates in PFM when a logic high voltage is applied to the EN pin greater than VIN

– 200mV. Tying the EN pin to the VIN pin is

sufficient to achieve this threshold condition.

The device operates in PWM regardless of output load when a logic high voltage is applied to the EN pin less than VIN

– 200mV. Using an

external resistive divider to create a difference in voltage between the VIN and EN pins is sufficient to achieve this threshold condition.

AP61302

VIN

EN

SW

FB

GND

INPUT

R1

200kΩ

R2

100kΩ

C2

22µF

C1

22µF

OUTPUT

VOUT

1.8V

PG

L

1μH

C3

33pF

R3

100kΩ

R4

200kΩ

Figure 41. Example Application Circuit for Forced PWM Operation

4

Power-Good (PG) Indicator (AP61302)

The PG pin of AP61302 is an open-drain output that is actively held low during the soft-start period until the output voltage reaches 95% of its

target value. When the output voltage is outside of its regulation by ±10%, PG pulls low until the output returns within 5% of its set value. The PG

rising edge transition is delayed by 40

μs. The PG pin is connected to VIN through an internal 5MΩ pull-up resistor.

5

Undervoltage Lockout (UVLO) and Input Overvoltage Protection (OVP)

Undervoltage lockout is implemented to protect the IC from insufficient input voltages. The AP61300/AP61302 disables if the input voltage falls

below 2.2V. In this UVLO event, both the high-side and low-side power MOSFETs turn off and the 125

Ω active discharge enables to discharge the

output voltage to ground.

Similarly, input overvoltage protection is implemented to protect the IC from excess input voltages. The AP61300/AP61302 disables if the input

voltage rises above 6.3V. In this OVP event, both the high-side and low-side power MOSFETs turn off and the 125

Ω active discharge enables to

discharge the output voltage to ground.