Datasheet

LP2981-N
SNOS773K –MARCH 2000–REVISED APRIL 2013 www.ti.com
ON/OFF INPUT OPERATION
The LP2981-N is shut off by pulling the ON/OFF input low, and turned on by driving the input high. If this feature
is not to be used, the ON/OFF input should be tied to V
IN
to keep the regulator on at all times (the ON/OFF input
must not be left floating).
To ensure proper operation, the signal source used to drive the ON/OFF input must be able to swing above and
below the specified turn-on/turn-off voltage thresholds which specify an ON or OFF state (see ELECTRICAL
CHARACTERISTICS).
The ON/OFF signal may come from either a totem-pole output, or an open-collector output with pull-up resistor to
the LP2981-N input voltage or another logic supply. The high-level voltage may exceed the LP2981-N input
voltage, but must remain within the Absolute Maximum Ratings for the ON/OFF pin.
It is also important that the turn-on/turn-off voltage signals applied to the ON/OFF input have a slew rate which is
greater than 40 mV/μs.
NOTE
IMPORTANT: The regulator shutdown function will not operate correctly if a slow-moving
signal is applied to the ON/OFF input.
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