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API9221

CAR/WALL OR USB SUPPLY INPUT LITHIUM BATTERY CHARGER WITH OVP USB BYPASS AND 10mA LDO

Diodes Incorporated. 

API9221

Functional Characteristics

Logic Description

A Logic State Table and diagrams of timing and charge profile are given at the end of this description.

The battery charge function is disabled when the EN input is pulled to logic HIGH. This normally requires an external pull-up

resistor connected to the system microcontroller I/O power supply. The API9221 has an internal resistor connected from this pin

to GND, typically 600kΩ. In many applications a suitable pull-up resistor value is 100kΩ. When EN is pulled LOW or left open

circuit, charging is enabled as described below.

There are two open-drain logic outputs, PPR and CHG . Each of these can use an external pull-up resistor to an appropriate

supply such as the microcontroller I/O supply, or can be left open circuit. A suitable value is 100kΩ. Alternatively these can each

be used to drive an indicator LED up to a maximum of 10mA.

The output PPR is LOW when a valid power supply voltage is present at the VDC input or at the VUSB input, independent of

EN . One of the two input voltages must be greater than the power-on threshold and less than the overvoltage protection

threshold.

The output CHG is LOW when the battery is charging, but only until the End-of-Charge (EOC) condition is reached. Together

with other conditions as described below, the voltage at the battery connection BAT is used to control the charging current. In the

EOC state, CHG is HIGH to indicate that the charging phase has completed and the battery voltage has reached 4.2V (± 1%).

In this state, the charger remains active and is able to supply load current and top up the battery as necessary. CHG may be re-

set as described below under Charge Conditions.

Auxiliary Outputs

The USB_BYP and VDC_LDO outputs are available independently of the EN input state. This allows a host controller to power

up initially.

USB Bypass, USB_BYP

The output USB_BYP provides power from the USB input when a valid power supply voltage is present at the VUSB input. It is

current limited to 400mA (nominally). It is therefore safely limited in current and voltage within the USB standard.

VDC Low dropout regulator VDC_LDO

This output provides a regulated 4.94V supply, up to 10mA, when a valid power supply voltage is present at the VDC input.

Charge Conditions

Before charging can begin, one of the two input voltages must also exceed the battery voltage enough to overcome the input-

output comparator offset. When one of the supplies satisfies these conditions, and EN is LOW, charging begins regardless of

the state of the other supply. The valid input conditions are:

For VDC: VPOR < VDC < OVPVDC and VDC > VBAT +VOSHC

For VUSB: VPOR < VUSB < OVPVUSB and VUSB > VBAT + VOSHC

Where VPOR is the rising power-on threshold voltage, and VOSHC is the rising input offset voltage relative to VBAT. All these

threshold voltages have defined hysteresis.

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.

API9221

Document number: DS32204 Rev. 3 - 3

8 of 16

www.diodes.com

June 2016

© Diodes Incorporated

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