LP5922 datasheet(12/24 Pages) TI1

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LP5922

SNVSAG0 – NOVEMBER 2016

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Feature Description (continued)

7.3.7

Power Good Output

The LP5922 has a Power-Good function that works by toggling the state of the PG output pin. When the output

voltage falls below the PG threshold voltage (PGLTH), the PG pin open-drain output engages (low impedance to

GND). When the output voltage rises above the PG threshold voltage (PGHTH), the PG pin becomes high-

impedance. By connecting a pullup resistor to an external supply, any downstream device can receive PG as a

logic signal. User must make sure that the external pullup supply voltage results in a valid logic signal for the

receiving device or devices; use a pullup resistor from 10 k

Ω to 100 kΩ for best results.

In Power-Good function, the PG output pin pulled high immediatelly after output voltage rises above the PG

threshold voltage.

7.4 Device Functional Modes

7.4.1 Enable (EN)

The LP5922 enable (EN) pin is internally held low by a 2-M

Ω resistor to GND. If the EN pin is open the output is

OFF. The EN pin voltage must be higher than the VIH threshold to ensure that the device is fully enabled under

all operating conditions. When the EN pin is pulled low, and the output is disabled, the output automatic

discharge circuit is activated. Any charge on the OUT pin is discharged to GND through the internal pulldown

resistance.

7.4.2 Undervoltage Lockout (UVLO)

The LP5922 incorporates UVLO. The UVLO circuit monitors the input voltage and keeps the LP5922 disabled

while a rising VIN is less than 1.2 V (typical). The rising UVLO threshold is approximately 100 mV below the

recommended minimum operating VIN of 1.3 V.

7.4.3 Minimum Operating Input Voltage

The LP5922 internal circuit is not fully functional until VIN is at least 1.3 V. The output voltage is not regulated

until VIN has reached at least the greater of 1.3 V or (VOUT + VDO).

LP5922 Datasheet(PDF) 12 Page - Texas Instruments