LTC1479 datasheet(7/24 Pages) LINER

7 / 24 page

LTC1479

PIN FUNCTIONS

SENSE – (Pin 14): Inrush Current Input. This pin should

be connected directly to the “bottom” (output side) of the

low valued resistor in series with the three input power

selector switch pairs, SW A/B, SW C/D and SW E/F, for

detecting and controlling the inrush current into and out

of the power supply sources and the output capacitor.

Battery Charging Switches

GG, GH (Pins 29, 27): Charger Switch Gate Drive. These

two pins drive the gates of the back-to-back N-channel

switch pairs, SW G and SW H, between the charger output

and the two batteries.

SG, SH (Pin 28, 26): Source Returns. These two pins are

connected to the sources of SW G and SW H respectively.

A small pull-down current source returns these nodes to

0V when the switches are turned off.

CHGMON (Pin 31): Battery Selector Output. This pin is

the output of an internal switch which is connected to

BAT1 and BAT2 and connects the positive terminal of the

selected battery to the voltage feedback resistors in the

charger circuit.

Microprocessor Interface

DCINGOOD (Pin 25): Comparator Output. This open-drain

output has an internal 2

µA pull-up current source con-

nected through a diode to the VCCP power supply. An

external pull-up resistor can be added if more pull-up

current is required. This output is active high when the DC

supply rises above the programmed voltage.

LOBAT (Pin 3): Comparator Output. This open-drain out-

put does not have an internal pull-up current source and

is active low when the selected battery voltage drops

below the programmed voltage.

DCIN/BAT (Pin 24): Selector Input. This high impedance

logic input allows the

µP to make the ultimate decision on

the connection of the DC power source, based upon the

DCINGOOD pin information. In some minimized systems,

the DCIN/BAT pin may be connected directly to the

DCINGOOD pin.

BATDIS (Pin 23): Battery Disconnect Input. This high-

impedance logic input has a built-in 2

µA pull-up current

source and allows the

µP to disconnect the battery from

the system.

3DM (Pin 22): Three Diode Mode Input. This high imped-

ance logic input has no built-in pull-up current source.

Connect a 100k resistor from this pin to ground to ensure

three diode mode operation from a “cold start.”

CHGSEL (Pin 21): Battery Charger Selector Input. This

high impedance logic input has a built-in 2

µA pull-up

current source and allows the

µP to determine which

battery is being charged by connecting the selected

battery to the charger output via one of the switch pairs,

SW G or SW H. (The charger voltage feedback ladder is

simultaneously switched to the selected battery.)

BATSEL (Pin 30): Battery Selector Input. This high imped-

ance logic input has a built-in 2

µA pull-up current source

and allows the

µP to select which battery is connected to

the system and the battery monitor comparator input.

Battery 1 is selected with a logic high on this input and

battery 2 is selected with a logic low.

LTC1479 Datasheet(PDF) 7 Page - Linear Technology

LTC1479 Datasheet(HTML) 7 Page - Linear Technology

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

Datasheet Download

Link URL