LTC2950-1/LTC2950-2
6
295012fd
V
IN
(Pin 1/Pin 4): Power Supply Input: 2.7V to 26.4V.
PB (Pin 2/Pin 3): Pushbutton Input. Connecting PB to
ground through a momentary switch provides on/off
control via the EN/EN pin. An internal 100k pull-up resis-
tor connects to an internal 1.9V bias voltage. The rugged
PB input can be pulled up to 26.4V externally without
consuming extra current.
ONT (Pin 3/Pin 2): Additional Adjustable Turn On Time
Input. Placing an external capacitor to ground determines
the additional time (beyond the internal default 32ms)
the PB pin must be held low before the enable output
is asserted. Floating this pin results in a default turn on
debounce time of 32ms.
GND (Pin 4/Pin 1): Device Ground.
INT (Pin 5/Pin 8): Open Drain Interrupt Output. After a
pushbutton turn-off event is detected, the LTC2950 inter-
rupts the system (µP) by bringing the INT pin low. Once the
system finishes its power down and housekeeping tasks,
it sets KILL low, which in turn releases the enable output.
If at the end of the power down timer (1024ms) KILL is
still high, the enable output is released immediately. INT
may optionally be tied to KILL to release the enable output
immediately after the turn-off event has been detected
(INT = low).
EN (LTC2950-1, Pin 6/Pin 7): Open Drain Enable Output.
This pin is intended to enable system power. EN is asserted
high after a valid PB turn on event. EN is released low if: a)
KILL is not driven high (by µP) within 512ms of the initial
valid PB power turn-on event, b) KILL is driven low dur-
ing normal operation, c) a second valid PB event (power
turn-off) is detected. This pin can connect directly to a
DC/DC converter shutdown pin that provides an internal
pull-up. Otherwise a pull-up resistor to an external supply
is required. The operating range for this pin is 0V to 10V.
EN (LTC2950-2, Pin 6/Pin 7): Open Drain Enable Output.
This pin is intended to enable system power. EN is asserted
low after a valid PB turn-on event. EN releases high if: a)
KILL is not driven high (by µP) within 512ms of the initial
valid PB power turn-on event, b) KILL is driven low dur-
ing normal operation, c) a second valid PB event (power
turn-off) is detected. This pin can connect directly to a
DC/DC converter shutdown pin that provides an internal
pull-up. Otherwise a pull-up resistor to an external supply
is required. The operating range of this pin is 0V to 10V.
OFFT (Pin 7/Pin 6): Additional Adjustable Turn Off Time
Input. A capacitor to ground determines the additional
time (beyond the internal default 32ms) that the PB pin
must be held low before initiating a power down sequence
(INT falling). Floating this pin results in a default turn off
time of 32ms.
KILL (Pin 8/Pin 5): KILL Input. Forcing KILL low releases
the enable output. During system turn on, this pin is blanked
by a 512ms internal timer to allow the system to pull KILL
high. This pin has an accurate 0.6V threshold and can be
used as a voltage monitor input. If unused, connect to a
low voltage output supply (see Figure 6).
Exposed Pad (Pin 9): Exposed Pad may be left open or
connected to device ground.
(TSOT-23/DFN)
pin FuncTions
