API9221

Car/Wall or USB Supply Input Lithium Battery Charger

with OVP USB Bypass and 10mA LDO

API9221

Document number: DS32204 Rev. 1 - 2

11 of 17

www.diodes.com

May 2010

© Diodes Incorporated

Fault Summary and Protection

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.