7

FN6687.0

February 13, 2009

Functional Pin Description

CRDL (Pin 1)

Cradle input. This pin is usually connected to a cradle power

input. The maximum input voltage is 28V. The charge

current from this pin is programmable with the ICDL pin up to

1A. When this pin is connected to a power source, no charge

current is drawn from the USB pin. A 1µF or larger value

ceramic capacitor is recommended for decoupling.

USB (Pin 2)

USB input. This pin is usually connected to a USB port

power connector. Other sources that are also acceptable.

The charge current from the USB pin is fixed at typically

380mA. A 1µF or larger value ceramic capacitor is

recommended for decoupling. It is also recommended to

have a 1

Ω resistor in series with the decoupling capacitor to

prevent an over-shoot voltage when a USB cable is plugged

in.

PPR (Pin 3)

Power presence indication. An open-drain output pin which

turns ON when either the USB input voltage or the CRDL

input voltage is within the power good range (refer to the

Description section for definition of power good condition),

regardless if the charger is enabled or disabled. Otherwise

turns OFF. This pin provides a wake-up signal to a

microprocessor when either the cradle or the USB power is

connected.

CHG (Pin 4)

Charge indication pin. An open-drain output which turns ON

when the charge current is above programmable threshold.

Otherwise turns OFF.

EN (Pin 5)

Enable logic input. Connect to LOW or leave floating to

enable the charger.

IMIN (Pin 6)

IMIN is the programmable input for the end-of-charge

current. IMIN is calculated by Equation 1:

USB charging.

VF (Pin 7)

VF is an input pin for the battery ID resistor connection. This

pin has an internal 1000k

Ω pull-up resistor. Thus a typical

20k

Ω ID resistor will pull this pin to logic low state, indicating

a valid battery connection. If the battery is removed, the VF

pin will be pulled to a logic high state by the internal resistor,

the charger will be disabled as a result, regardless of the

status of the EN pin. The maximum ID resistor is 100k

Ω.

GND (Pin 8)

System ground.

ICDL (Pin 9)

The ICDL pin has two functions. The first function is to

program the cradle charge current during the constant-

current mode. The voltage of this pin is 1.22V during the

constant-current mode of the cradle charger. The constant-

current mode current is programmed by Equation 2:

FIGURE 9. CRADLE INPUT QUIESCENT CURRENT vs INPUT

VOLTAGE

FIGURE 10. USB INPUT QUIESCENT CURRENT vs INPUT

VOLTAGE

0

100

200

300

400

500

600

700

800

0

5

10

15

20

25

TEMPERATURE (°C)

DISABLED

ENABLED

DISABLED

ENABLED

0

100

200

300

400

500

600

700

800

0

5

10

15

20

25

TEMPERATURE (°C)

DISABLED

ENABLED

DISABLED

ENABLED

I

MIN

550

R

IMIN

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

mA

()

=

(EQ. 1)

I

CDL

6820

R

ICDL

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

mA

()

=

(EQ. 2)

ISL9228