API9221 datasheet(9/17 Pages) DIODES

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API9221

Car/Wall or USB Supply Input Lithium Battery Charger

with OVP USB Bypass and 10mA LDO

API9221

Document number: DS32204 Rev. 1 - 2

9 of 17

www.diodes.com

May 2010

Functional Description (Continued)

When the charge current falls below IMIN, CHG goes HIGH (provided it has an external pull-up). This state is

latched and is not re-set until one of the following events occurs:

1. EN is driven HIGH and LOW again

2. The active supply is removed and re-applied

3. VBAT falls below the re-charge threshold of 3.9V (nominally)

Note that the outputs, BAT, USB_BYP and VDC_LDO are reverse current protected. If an external voltage higher

than the supply voltage is connected to one of these outputs, that output will be disabled.

Charging from Adapter Power (VDC pin)

The battery can be charged from an AC powered wall adapter or in-car adapter at a current of up to 1.2A using

this input pin. The maximum charge current is set by an external resistor, RIVDC connected between the IVDC and

GND pins. If VDC is greater than the power-on threshold voltage (VPOR) and less than the over-voltage protection

threshold (OVPVDC), the battery will begin to charge at a rate dependent on the battery voltage.

When VDC input is as recommended, (4.5V to 6.7V), no charge current is drawn from the VUSB input as VDC

takes precedence. Input operation below 4.5V is also possible, but the charging rate may be affected.

The resistor RIVDC determines the charge current according to

IVDC

6820

IVDC

Amp

For example, a resistor value of 13k

Ω sets a charge current of 0.525A. The recommended IVDC setting is 100mA

to 1200mA.

The maximum charge current available may be otherwise limited by the car/wall adapter current limit, by thermal

protection within the API9221, or by the rDS(ON) of the FET in the VDC charging path. For example, if IVDC is set

to 1A, there is a voltage drop of 0.6V due the typical rDS(ON) of 600mΩ at room temperature. Therefore, the voltage

at the VDC input must be at least 4.8V to charge the battery to 4.2V in the minimum time.

The VDC input is safe from damage up to 28V.

Charging from USB Power (VUSB pin)

The battery can be charged at a current of up to 0.5A from this pin. In this case the maximum available charge

current is set by an external resistor RIUSB connected between the IUSB and GND pins. If VUSB is greater than

the power-on threshold voltage (VPOR) and less than the over-voltage protection threshold (OVPVUSB), the battery

will begin to charge at a rate dependent on the battery voltage.

The resistor RIUSB resistor determines the charge current according to

IUSB

6820

IUSB

Amp

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