LTC2952 datasheet(23/28 Pages) LINER

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LTC2952

2952f

TYPICAL APPLICATIONS

Wall Adapter and Battery Automatic Load Switchover with Simple On/Off Push-Button

Control and Voltage Monitors for System Power Without µP

LTC2952

LT1767-2.5

SHDN

VOUT

VIN

PFI

INT

G1STAT

PFO

KILL

WDE

ONT

CONT*

22nF

GND

OFFT

COFFT*

68nF

511k

*OPTIONAL

2952 TA02

100k

Si7913DN

WALL ADAPTER

5V TO 20V

2.5V

Si7913DN

4.2V

SINGLE

CELL

Li-Ion

BATTERY

365k

100k

10k

RST

APPLICATIONS INFORMATION

Note that since the PB input is ignored in both mode 4 and

5, the only way to turn on the power path from these two

modes is a transition from 0 to 1 at the M2 pin. A transition

from 0 to 1 at the M2 pin in modes 4 or 5 is interpreted as

a digital on command. This digital on command causes

the mode to transition from mode 4 or 5 to mode 7. In

mode 7, both of the ideal diodes are enabled and the EN

pin goes high impedance. Modes 4, 5 and 7 are used in

Conﬁguration D (Figure 6).

Notice that in mode 7, both the M2 pin and the

⎯P⎯B pin

have direct control over the EN pin. A transition from 1

to 0 at the M2 pin in mode 7 is recognized as a digital off

command. This digital off command causes a transition to

mode 4 after a proper shutdown sequence. On the other

hand, a valid push-button off mode 7 transitions the part

to mode 6 after a proper shutdown sequence. In both

mode 4 and mode 6 the EN pin is driven low. Modes 6

and 7 are used in Conﬁguration C (Figure 5).

In mode 4 the ideal diode driver circuitry is disabled, the

EN pin is driven low, and the PB input is ignored. On the

other hand in mode 6, although both of the primary and

secondary ideal diodes are disabled and the EN pin is

set low, the PB input is not ignored. A valid push-button

transitions the part from mode 6 to mode 7 turning on

both the ideal diodes and setting the EN pin high imped-

ance (turning on the DC/DC converter).

LTC2952 Datasheet(PDF) 23 Page - Linear Technology

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