LP3879MR-1.2 Datasheet, PDF (10/18 Pages) Texas Instruments – LP3879 Micropower 800mA Low Noise "Ceramic Stable" Voltage Regulator for Low

LP3879
SNVS396B – MAY 2006 – REVISED APRIL 2013
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For these reasons, X7R and X5R type ceramic capacitors must be used on the input and output of the
LP3879.
SHUTDOWN INPUT OPERATION
The LP3879 is shut off by pulling 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 LP3879 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 LP3879 to
0.3V (see Absolute Maximum Ratings).
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