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FUNCTIONAL DESCRIPTION

BatteryVoltage,

Charge

Complete

Status,

Charger

Off

VoltageRegulationand

ChargeTermination

Phase

PRE-CHARGE

CURRENT AND

TERMINATION

THRESHOLD

BatteryCurrent,

DONE

DONE

FAST-CHARGE

CURRENT

I

I

O(PRECHG), (TERM)

Current

Regulation

Phase

Pre-

Conditioning

Phase

bq2406x

SLUS689A – JUNE 2006 – REVISED OCTOBER 2006

when an external input power is connected to the system, the charger is enabled by CE = LO and the battery

activated, if the safety timer function is enabled. The safety timer timeout value is set by an external resistor

connected to TMR pin.

When the charger is enabled two control loops modulate the battery switch drain to source impedance to limit

the BAT pin current to the programmed charge current value (charge current loop) or to regulate the BAT pin

voltage to the programmed charge voltage value (charge voltage loop). If V(BAT) < V(LOWV) (3 V typical) the

BAT pin current is internally set to 10% of the programmed charge current value.

A typical charge profile is shown below, for an operation condition that does not cause the IC junction

with the activation of the integrated thermal control loop. The thermal control loop is activated when an internal

voltage reference, which is inversely proportional to the IC junction temperature, is lower than a fixed,

temperature stable internal voltage. The thermal loop overrides the other charger control loops and reduces the

temperature.

9

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