APL3200 datasheet(14/24 Pages) ANPEC

14 / 24 page

Rev. A.5 - Apr., 2009

APL3200

www.anpec.com.tw

The enable input, EN, switches the charging of APL3200

on or off. With EN high, the APL3200 can begin charging.

When EN is low, DCOK and PON remain active. Charging

stops when EN is low, but the chip remains biased and

continues to draw current from the input supplies.

Therefore, power-monitoring outputs can remain valid.

DC Power-OK ( DCOK)

Function Description

Autonomous Power Source Selection

USB

Description

VDC>18V

VUSB<6.5V

VDC<18V

VUSB>6.5V

Exceeds operating input

range. Not allowed.

4V<VDC<6.4V

VUSB<6.5V

DCLV supplies charging

current.

VDC <4V or

VDC >6.4V

VUSB>4V

USB supplies charging

current.

VDC <4V or

VDC >6.4V

VUSB<4V

No charging.

The APL3200 charges a single-cell Li+ battery from either

USB power sources or AC adapter sources. The APL3200

includes voltage sensing, monitoring the voltage on the

DC pin, and switchover circuitry that selects the active

input source to supply charging current. When both inputs

are active, priority is given to the AC adapter. Table 1

describes the switchover between AC adaptor and USB

power sources.

When power is connected to DC, the APL3200 requires

20ms to validate the input. Consequently, charging is

interrupted for 20ms until it is determined that input power

is good. Also, when DC power is removed while valid

USB power is present, charging is interrupted for 20ms

before transferring to the USB source.

An additional power selection circuit selects one of the

power sources for control circutry of APL3200. The higher

voltage on either DCLV or USB supplies control circutry

with bias current through the selected internal MOSFET

connected from DCLV or USB to BYP. BYP is the bypass

connection for the APL3200’s internal power rail. Bypass

to the GND with a 2.2

µF or greater capacitor to reduce

voltage ripple.

Enable (EN)

DCOK is an active-low and open-drain output that goes

low when V

DC is below 6.4V and above 3.65V. DCOK can

be used as a logic output or to drive an external P-channel

MOSFET. This allows the charger to protect the input

from over-voltage up to 18V. Charging from AC adaptor is

disabled for inputs over 6.4V. An external 1k

Ω pull-up

resistor keeps DCOK high (external MOSFET off) until it

is the certain voltage within the acceptable range. To verify

that the input voltage is stable, DCOK has an internal

delay of 20ms before connecting power to DCLV. DCOK

remains operational when EN is low (charger off).

USB Power-OK ( UOK)

UOK is an active-low and open-drain output that goes low

to indicate that V

USB is valid (greater than 3.65V). UOK

remains operational when EN is low (charger off). An

external 10k

Ω pullup resistor keeps UOK high until it is

certain that power is within the acceptable range for 20ms.

UOK can be used as a logic output, or to control a MOSFET

that switches USB power directly to the system load when

the APL3200 is powered from a USB source.

Power On (PON)

PON goes high when V

DC or VUSB is within its normal

operating range(3.65V<V

DC<6.4V or VUSB>3.65V) to turn

off the external P-channel MOSFET, disconnecting the

battery from system load. Also, PON can be used as a

logic output to indicate power is connected.

The PON has an internal 10

Ω MOSFET for pulling up to

BYP voltage and an internal 120k

Ω resistor for pulling

down to the GND.

Precharge Current

When the APL3200 is powered with a battery connected,

the IC first detects if the cell voltage is ready for full charge

current. If the cell voltage is less than the prequal level

(3V typ.), the battery is precharged with a 50mA current

until the cell reaches the proper level. The full charging

current, as set by USEL or DCI, is then applied.

Table 1 USB and DC Input Selection

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