LP2986 datasheet(15/26 Pages) TI

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VIN

VOUT

PNP

GND

SCHOTTKY DIODE

LP2986

VIN

VOUT

PNP

GND

LP2986

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SNVS137H – MARCH 1999 – REVISED APRIL 2013

REVERSE INPUT-OUTPUT VOLTAGE

The PNP power transistor used as the pass element in the LP2986 has an inherent diode connected between

the regulator output and input.

During normal operation (where the input voltage is higher than the output) this diode is reverse-biased.

However, if the output voltage is pulled above the input, or the input voltage is pulled below the output, this diode

will turn ON and current will flow into the regulator output pin.

In such cases, a parasitic SCR can latch which will allow a high current to flow into VIN (and out the ground pin),

which can damage the part.

In any application where the output voltage may be higher than the input, an external Schottky diode must be

connected from VIN to VOUT (cathode on VIN, anode on VOUT), to limit the reverse voltage across the LP2986 to

0.3V (see the Absolute Maximum Ratings section.

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LP2986 Datasheet(PDF) 15 Page - Texas Instruments