LP3992

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SNVS192C – OCTOBER 2002 – REVISED NOVEMBER 2015

8.3 Feature Description

8.3.1 Shutdown and Enable

The LP3992 may be switched ON or OFF by a logic input at the EN pin. A high voltage at the EN pin turns the

device on. A low voltage on the EN pin will disable the regulator, and will activate the fast turnoff circuitry to

discharge the output capacitance. When the regulator is disabled the device typically consumes 3 nA.

If the application does not require the EN feature, the EN pin must be tied to VIN to keep the regulator output

permanently on.

To ensure proper operation, the signal source used to drive the EN input must be able to swing above and below

the specified turnon or turnoff voltage thresholds listed in the Electrical Characteristics under VIL and VIH.

8.3.2 Fast Turnon and Turnoff

The controlled shutdown feature of the device provides a fast turn off by discharging the output capacitor via an

internal FET device. This discharge is current limited by the RDSON of this switch. Fast turnon is ensured by

control circuitry within the reference block allowing a very fast ramp of the output voltage to reach the target

voltage.

8.4 Device Functional Modes

8.4.1 Enable Operation

The LP3992 may be switched ON or OFF by a logic input at the EN pin. A high voltage at the EN pin turns the

device on. A low voltage on the EN pin will disable the regulator, and will activate the fast turnoff circuitry to

discharge the output capacitance. When the regulator is disabled the device typically consumes 3 nA.

If the application does not require the EN feature, the EN pin should be tied to VIN to keep the regulator output

permanently on.

To ensure proper operation, the signal source used to drive the EN input must be able to swing above and below

the specified turnon or turnoff voltage thresholds listed in the Electrical Characteristics under VIL and VIH.

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