LTC4120 datasheet(14/24 Pages) AD

14 / 24 page

LTC4126-ADJ

Rev. 0

For more information www.analog.com

Figure 5. Various Pushbutton Scenarios

VOUT

TOO SHORT

LONG ENOUGH

425ms

43ms

LONG ENOUGH

PBEN

4126-ADJ F05

VOUT

LONG ENOUGH

425ms

43ms

TOO SHORT

(b) HIGH PULSE TOO SHORT, 2ND PUSH IGNORED, DC/DC STAYS ON

PBEN

VOUT

LONG ENOUGH

425ms

43ms

LONG ENOUGH

(a) VALID SUCCESSIVE PUSH, DC/DC TURNS ON AND OFF

PBEN

425ms

OPERATION

Pushbutton Control

The LTC4126-ADJ is equipped with a pushbutton control-

ler to turn the DC/DC converter on and off if the EN pin is

not used (held low). A logic high on the EN pin overrides

the pushbutton function and keeps the regulator on. On

the falling edge of the EN signal, the DC/DC shuts off and

1µs later, the pushbutton can control the output as long

as EN remains low. A push on the pushbutton is consid-

ered valid if the PBEN pin is held low for at least 425ms

(typical). Additionally, the PBEN pin needs to return to the

high state for at least 43ms (typical) in between succes-

sive pushes for a push to be considered valid. An invalid

push will not change the state of the converter. A 4MΩ

internal resistor pulls up the PBEN pin to the BAT voltage.

A few different scenarios of valid and invalid pushes are

illustrated in Figure 5.

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