API9221_16 datasheet(9/16 Pages) DIODES

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API9221

Document number: DS32204 Rev. 3 - 3

9 of 16

www.diodes.com

June 2016

API9221

Functional Characteristics (Cont.)

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 13kΩ sets a charge current of 0.525A. The recommended IVDC setting is 100mA to 1200mA.

Charging from Adapter Power (VDC pin) (Cont.)

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

For example, a resistor value of 22kΩ sets a charge current of 0.31A.

The recommended IUSB setting is 46.5mA to 465mA.

The maximum charge current available may be otherwise limited by the external USB current limit, or by thermal protection

within the API9221.

The RDS(ON) of the FET in the USB charging path is typically 600mΩ at room temperature. At the IUSB limit of 465mA, there is a

voltage drop of nearly 0.3V. Therefore, the voltage at the VUSB input must be at least 4.5V to charge the battery to 4.2V in the

minimum time.

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

Trickle Charge

When the battery voltage is below the Preconditioning Threshold, VMIN, the charger is in the Trickle Charge state and the charge

current is limited to 18% of the available charge current set by RIVDC or RIUSB. If the USB charge current is programmed to a

value less than the VDC trickle charge, then this value of the USB current is used in trickle mode (no derating).

When the battery voltage reaches VMIN, the charge current increases to 100% of the available charge current.

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