API9221FCG datasheet(10/16 Pages) DIODES

10 / 16 page

API9221

Document number: DS32204 Rev. 3 - 3

10 of 16

www.diodes.com

June 2016

API9221

Functional Characteristics (Cont.)

End-of-Charge Current

During charging, as the battery voltage approaches the regulated value of 4.2V, the charging current will begin to decrease.

Eventually the charging current settles to a value just low enough to maintain the regulated voltage. When the current becomes

less than the End-of-Charge threshold current, IMIN, the logic output CHG goes HIGH. The threshold current is set by an

external resistor connected between the IMIN and GND pins. This is independent of whether the VDC or VUSB input is valid.

The resistor at IMIN determines the EOC threshold current according to

IMIN

MIN

550



Amp

For example, a resistor value of 10kΩ sets the EOC threshold current to 55mA.

Accuracy

When the constant voltage phase has been reached, the battery is charged to 4.2V ±1%. This is the maximum error over the

ambient temperature range from -40°C to +85°C.

Fault Summary and Protection

Overvoltage protection: If VDC is greater than OVPVDC (6.9V), the VDC charging path is turned off until VDC falls below OVPVDC

- HOVPVDC, where HOVPVDC is the OVP hysteresis. Similarly, if VUSB is greater than OVPVUSB (5.4V), the USB charging path

is turned off until VUSB falls below OVPVUSB – HOVPVUSB.

USB_BYP current limit: The USB_BYP load current is limited to 400mA (Nominally).

USB_BYP reverse blocking: If the voltage at USB_BYP is greater than VUSB, the USB bypass path is turned off.

BAT reverse blocking: If the battery voltage is greater than either VDC or VUSB, the relevant charge path is turned off.

VDC_LDO reverse blocking: If the voltage at VDC_LDO is greater than VDC, the linear regulator is turned off.

Thermal protection: When the junction temperature reaches 125°C, a current foldback circuit is activated. This effectively limits the

power dissipation to a safe level.

Power Supply Filtering and Stability

At each of the inputs VDC and VUSB, a local decoupling capacitor is required to be connected to GND. A minimum value of 1µF

is recommended, ceramic type X7R. (The USB standard sets an upper bound of capacitance somewhat larger than this.)

At the linear regulator output VDC_LDO, a local decoupling capacitor is required, connected to GND. A value of 1µF is

recommended, ceramic type X7R.

At the battery connection BAT, a local decoupling capacitor is required, connected to GND. A value of 1µF is recommended,

ceramic type X7R.

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