LP2983_15 Datasheet, PDF (10/18 Pages) Texas Instruments – LP2983 Micropower 150 mA Voltage Regulator in SOT-23 Package For Output Voltages ≤ 1.2V Designed for Use with Very Low ESR Output Capacitors

LP2983
SNVS170C – OCTOBER 2001 – REVISED APRIL 2013
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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).
LP2983
V_IN
PNP
V_OUT
GND
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).
SCHOTTKY DIODE
LP2983
V_IN
PNP
V_OUT
GND
Figure 24. Adding External Schottky Diode Protection
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