bq24400

SLUS498A – SEPTEMBER 2001 – REVISED FEBRUARY 2010

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These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam

during storage or handling to prevent electrostatic damage to the MOS gates.

PIN DESCRIPTIONS

SNS

Current-sense input

Enables the bq24400 to sense the battery current via the voltage developed on this pin by an

external sense-resistor connected in series with the battery pack

System Ground

Connect to the battery’s negative terminal

LED

Charge-status output

Open-drain output that indicates the charging status by turning on, turning off, or flashing an external

LED, driven through a resistor.

BAT

Battery-voltage input

Battery-voltage sense input. A simple resistive divider, across the battery terminals, generates this

input.

TS

Temperature-sense input

Input for an external battery-temperature monitoring circuit. An external resistive divider network with

a negative temperature-coefficient thermistor sets the lower and upper temperature thresholds.

RC

Timer-program input

Used to program the maximum fast charge-time, maximum top-off charge-time, hold-off period, trickle

connect to this pin.

Supply-voltage input

Recommended bypassing is 10µF + 0.1µF to 0.22µF of decoupling capacitance near the pin.

MOD

Modulation-control output

Push-pull output that controls the charging current to the battery. MOD switches high to enable

charging current to flow and low to inhibit charging-current flow.

2

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