DIA7976

Version 1.9, Apr 2025

www.dioo.com

© 2025 Dioo Microcircuits Co., Ltd. Jiangsu

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Figure 21. Current limit

9.5.Power-good function (PG)

To indicate the status of the output voltage, the power-good circuit monitors the voltage at the FB pin. If the

output voltage is below PGLTH (PG low threshold), the PG pin open-drain output activates and pulls the PG pin

close to GND. If the output voltage is higher than PGHTH (PG high threshold), then the PG pin will be high

impedance.

A pull-up resistor is needed for the open-drain output. Any downstream device can receive power-good as a

logic signal for sequencing through attaching a pull-up resistor to an external supply. Furthermore, the

open-drain output may be linked to other open-drain outputs to implement AND logic. Check to see if the

external pull-up supply voltage produces a valid logic signal for the receiving device. It is advised to use a pull-up

resistor ranging from 10 kΩ to 100 kΩ. While for push-pull PG option, the pull-up resistor is not needed. The

push-pull PG option has a high logic signal correlating with the output voltage. The push-pull option is only valid

for VOUT ≥ 1 V and please do not link the push-pull output to other logic outputs.

If CFF (feed-forward capacitor) is used, the time constant for the LDO start-up is increased while the time

constant for PG output remains unchanged, which may leading to an invalid PG output. To avoid the situation,

DIOO recommend to ensure the time constant of both LDO start-up and PG output match by adding a capacitor

in parallel with the power-good pull-up resistor.

To make the PG valid, the device should operate above the minimum VIN and PG is asserted, regardless of the

output voltage state when VIN is below VUVLO minus VUVLO, HYST. When VIN falls below about 0.8 V, power-good

device turns on and the power-good output pulls high because of no enough gate drive voltage to keep the

open-drain. This effect can be minimized by connecting the PG pull-up resistor to the output voltage.

9.6.Thermal shutdown

The DIA7976 has a thermal shutdown protection feature that disables the device when the junction temperature

rises to approximately 165°C. This feature helps to reduce the power dissipated by the device, allowing it to cool

down. When the temperature falls to approximately 150°C, the output circuitry is re-enabled. However,

depending on various factors like power dissipation, thermal resistance, and ambient temperature, the thermal