Datasheet

LP2989LV
www.ti.com SNVS086J –MAY 2000–REVISED APRIL 2013
Shutdown Input Operation
The LP2989LV is shut off by driving the Shutdown input low, and turned on by pulling it high. If this feature is not
to be used, the Shutdown input should be tied to V
IN
to keep the regulator output on at all times.
To assure proper operation, the signal source used to drive the Shutdown input must be able to swing above and
below the specified turn-on/turn-off voltage thresholds listed in the ELECTRICAL CHARACTERISTICS section
under V
ON/OFF
.
Reverse Input-Output Voltage
The PNP power transistor used as the pass element in the LP2989LV 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 is pulled above the input, 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 V
IN
(and out the ground pin),
which can damage the part.
In any application where the output may be pulled above the input, an external Schottky diode must be
connected from V
IN
to V
OUT
(cathode on V
IN
, anode on V
OUT
), to limit the reverse voltage across the LP2989LV to
0.3V (see ABSOLUTE MAXIMUM RATINGS).
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