6

FN9102.2

May 2, 2005

Functional Pin Description

VIN (Pin 1, 15, 16)

VIN is the input power source pin that is connected to a wall

adapter.

FAULT (Pin 2)

FAULT is an open-drain output indicating fault status. When

a fault condition occurs, this pin is pulled to LOW.

STATUS (Pin 3)

STATUS is an open-drain output indicating charging and

inhibit states. During any charge mode, this pin is pulled to

LOW.

TIME (Pin 4)

GND. The internal oscillator, as shown in the Block Diagram,

charges and discharges the timing capacitor between 0.5V

found as:

A 22-stage binary counter increments each oscillation period

to set up the TIMEOUT interval. The TIMEOUT interval can

be calculated as:

When the fast charge takes longer than the TIMEOUT

interval, or the Trickle charge time exceeds 1/8 of the

TIMEOUT interval, the charger issues a TIMEOUT fault

status and stops charging.

The oscillator also provides a time reference for the charger.

GND (Pin 5)

GND is the connection to system ground.

TOEN (Pin 6)

TOEN is the TIMEOUT enable input pin. Pulling this pin to

LOW disables the TIMEOUT charge-time limit for the fast

charge modes. Leave this pin floating to enable the

TIMEOUT limit. An internal 10

µA pull-up circuit pulls this pin

up to a 2.8V internal reference. The trickle mode always has

the 1/8 TIMEOUT limited charge time regardless of this

input. When a TIMEOUT fault is issued, the charger is

latched. The only way to enable the charger again is to cycle

the input power, or to toggle the EN pin.

EN (Pin 7)

EN is the CMOS logic input. Leave this pin floating to enable

the charger. This pin is pulled up to the internal 2.8V

reference via a 10

µA current source.

V2P8 (Pin 8)

V2P8 is a 2.8V reference voltage output. V2P8 pin outputs a

2.8V voltage when the input voltage rises above the POR

threshold and outputs zero voltage otherwise. This pin can

be used as an adapter presence signal. A 0.1

µF Ceramic

capacitor is recommended for decoupling purposes. This pin

can be used to bias other circuits with a maximum current of

2mA.

IREF (Pin 9)

IREF is the programming input for the constant charge

Application) to this pin. The voltage of this pin is regulated to

a 0.8V reference voltage. The charging current during the

constant current mode charge is 100,000 times of the

constant current mode can be found as:

IMIN (Pin 10)

IMIN is a programmable input for the end-of-charge current.

The pin voltage is also regulated at 0.8V. The end-of-charge

current can be found as:

TEMP (Pin 11)

TEMP is an Input for an external NTC thermistor. As shown

in the Block Diagram, two comparators forms a window

is outside the window, the charger stops. When the TEMP

pin voltage falls back into the window, the charger starts a

determined by the internal resistor divider, as shown in the

block diagram. See “Battery Pack Temperature Monitoring”

for more information.

The TEMP pin is also used for battery removal detection. It

is assumed that the thermistor is co-packed with the battery.

When the charger sees a TEMP pin voltage that is 2.1V or

higher, it assumes that the battery is removed. When a

battery is removed, a FAULT signal is indicated and charging

is halted. When a battery is inserted again, a new charge

cycle starts.

VBAT (Pin 12, 13, 14)

VBAT is the connection to a battery. Typically a 10

µF

Tantalum capacitor is needed for stability when no battery is

attached to this pin. When a battery is connected, however,

no capacitor is required for stability. A 0.1

µF ceramic

capacitor is recommended for decoupling.

0.2 10

TIME

⋅

⋅

=

onds

sec

()

TIMEOUT

2

OSC

14

1nF

------------------

⋅

=

⋅

=

minutes

()

100000

-----------------

0.8V

-----------------

5

×10 A

()

=

⋅

=

10000

----------------

0.8V

----------------

4

×10 A

()

=

⋅

=