LTC2954I データシートの表示（PDF） - Linear Technology

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LTC2954I

Pushbutton On/Off Controller with µP Interrupt

Linear Technology 

LTC2954

PIN FUNCTIONS (TSOT-23/DFN)

VIN (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 and INT outputs. An internal 100k

pull-up resistor connects to an internal 1.9V bias voltage.

The rugged PB input withstands ±10kV ESD HBM and

can be pulled up to 26.4V externally without consuming

extra current.

ONT (Pin 3/Pin 2): Turn-On Time Input. Placing an external

capacitor to ground determines the additional time (6.4

seconds/μF) 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 (tDB,OFF), the LTC2954

interrupts the system (μP) by asserting the INT pin low.

The μP would perform power-down and housekeeping

tasks and then assert the KILL pin low, thus releasing the

enable output. The INT pulse width is a minimum of 32ms

and stays low as long as PB is asserted. If PB is asserted

for longer than tPD,MIN + tPDT, the INT and EN/EN outputs

are immediately released.

EN (LTC2954-1, 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 (tDB,ON + tONT). 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 during normal operation, c) PB is pressed

and held low (tPD,MIN + tPDT) during normal operation. 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 low leakage pin is 0V to 26.4V.

EN (LTC2954-2, Pin 6/Pin 7): Open Drain Enable Bar

Output. This pin is intended to enable system power. EN is

asserted low after a valid PB turn-on event (tDB,ON + t ONT).

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 during normal operation, c) PB is pressed

and held low (tPD,MIN + tPDT) during normal operation. 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 26.4V.

PDT (Pin 7/Pin 6): Power-Down Time Input. A capacitor

to ground determines the additional time (6.4 seconds/μF)

that the pushbutton must be held low before immediately

releasing the EN/EN and INT outputs. Floating this pin

results in a pushbutton power-down time of 64ms.

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 (tKILL,ON BLANK) 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 DFN Only): Exposed Pad may be left

open or connected to device ground.

2954fb

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