LP2983 datasheet(11/25 Pages) TI1

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VIN

VOUT

PNP

GND

SCHOTTKY DIODE

LP2983

VIN

VOUT

PNP

GND

LP2983

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SNVS170D – OCTOBER 2001 – REVISED APRIL 2016

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Feature Description (continued)

7.3.3 Reverse Input-Output Voltage

The internal PNP power transistor used as the pass element in the LP2983 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 (See Figure 21).

Figure 21. LP2983 Reverse Current Path

However, if the input voltage is more than a VBE below the output voltage, this diode turns ON and current flows

into the regulator output. In such cases, a parasitic SCR can latch which allows a high current to flow into the VIN

pin and out the ground pin, which can damage the part.

The internal diode can also be turned on if the input voltage is abruptly stepped down to a voltage which is a VBE

below the output voltage.

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

must be connected from VIN to VOUT (cathode on VIN, anode on VOUT — see Figure 22), to limit the reverse

voltage across the LP2983 to 0.3 V (see Absolute Maximum Ratings).

Figure 22. Adding External Schottky Diode Protection

LP2983 Datasheet(PDF) 11 Page - Texas Instruments