Datasheet

V
IN
V
OUT
PNP
GND
SCHOTTKY DIODE
LP2983
V
IN
V
OUT
PNP
GND
LP2983
LP2983
SNVS170C –OCTOBER 2001–REVISED APRIL 2013 www.ti.com
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 23).
Figure 23. LP2983 Reverse Current Path
However, if the input voltage is more than a V
BE
below the output voltage, this diode will turn ON and current will
flow into the regulator output. In such cases, a parasitic SCR can latch which will allow a high current to flow into
the V
IN
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 V
BE
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 V
IN
to V
OUT
(cathode on V
IN
, anode on V
OUT
. See Figure 24), to limit the reverse voltage
across the LP2982 to 0.3V (see Absolute Maximum Ratings).
Figure 24. Adding External Schottky Diode Protection
10 Submit Documentation Feedback Copyright © 2001–2013, Texas Instruments Incorporated
Product Folder Links: LP2983