APM8600

SINGLE CELL LINEAR LITHIUM BATTERY CHARGER

WITH 28V OVP AND PROGRAMMABLE CHARGE TIMER

APM8600

Document number: DS35140 Rev. 1 - 2

9 of 14

www.diodes.com

December 2010

© Diodes Incorporated

Functional Description (continued)

CT

The Charge Timer input on pin 5 allows selection of how long the system timers for Prequal, Charge and Top-off

⎟

⎠

⎞

⎜

⎝

⎛

×

=

nF

68

CCT

min

334

TCHARGE

⎟

⎠

⎞

⎜

⎝

⎛

×

=

=

nF

68

CCT

min

34.8

TTOPOFF

TPREQUAL

The charge timer will hold its current value if the charging was stopped via the thermistor and continue when the battery is in

a valid temperature range for charging.

OUTPUTS

BAT

Pin 1 is the current-controlled charging output for the battery cell. It should be connected to the positive terminal of

the battery. The chip monitors the voltage on this pin. There should be a 2.2µF capacitor connected from BAT to GND.

POK

The POK flag on pin 10 is pulled low when a valid power input is available on DC. It will go high when no valid

power is available and the device will enter the Disable state.

CHG

The CHG flag at pin 11 is pulled low when the device is in the Charge state. It will be high in Prequal and Top-off

states. If the thermistor trips the circuit into the THM state (from Prequal or Charge states), CHG will hold its previous value.

FLT

The FLT flag on pin 14 indicates a battery fault, as determined by a time-out in either the Prequal or Charge states.

If the battery voltage does not reach 3V after the prequal timer (default 34.8mins), or does not reduce charging current to

7.5% after the charge timer (default 334mins), this indicates that the battery has failed or is failing and this will trigger the

FLT flag. This flag will not automatically reset, and can only be cleared by cycling the power input or the EN pin.