AAT3689 データシートの表示（PDF） - Advanced Analogic Technologies

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AAT3689

0.5A/1.0A USB Port/Adapter Lithium-Ion/Polymer Battery Charger

Advanced Analogic Technologies 

AAT3689

0.5A/1.0A USB Port/Adapter

Lithium-Ion/Polymer Battery Charger

tolerance metal film resistors are recommended for

the set resistor function.

ADP fast charge constant current levels from 100mA

to 1.0A may be set by selecting the appropriate

resistor value from Table 1.

The USB charge may be set to any level between

50mA and 500mA depending upon the system

design requirements for a given USB charge appli-

cation. Refer to Table 1 and Figure 2 for recom-

mended RSETUSB values.

10000

1000

ADP

100

USB

10

1

10

100

1000

RSET (kΩ)

Figure 2: IFASTCHARGE vs. RSET.

Protection Circuitry

Programmable Watchdog Timer

The AAT3689 contains a watchdog timing circuit for

the adapter input charging mode. No watchdog tim-

ing functions are active for the USB input mode.

Typically, a 0.1μF ceramic capacitor is connected

between the CT pin and ground. When a 0.1μF

ceramic capacitor is used, the device will time a

shutdown condition if the trickle charge mode

exceeds 25 minutes or the combined trickle charge

plus fast charge mode exceeds three hours. When

the device transitions to the constant voltage

mode, the timing counter is reset and will time out

after three hours and shut down the charger.

Mode

Trickle Charge (TC) Time Out

Trickle Charge (TC) +

Fast Charge (CC) Time Out

Constant Voltage (VC) Mode

Time Out

Time

25 minutes

3 hours

3 hours

Table 2: Summary for a 0.1μF Used for the

Timing Capacitor.

14

The CT pin is driven by a constant current source

and will provide a linear response to increases in

the timing capacitor value. Thus, if the timing

capacitor were to be doubled from the nominal

0.1μF value, the time-out times would be doubled.

If the programmable watchdog timer function is not

needed, it may be disabled by connecting the CT

pin to ground. The CT pin should not be left float-

ing or un-terminated, as this will cause errors in the

internal timing control circuit.

The constant current provided to charge the timing

capacitor is very small, and this pin is susceptible

to noise and changes in capacitance value.

Therefore, the timing capacitor should be physical-

ly located on the printed circuit board layout as

closely as possible to the CT pin. Since the accu-

racy of the internal timer is dominated by the

capacitance value, 10% tolerance or better ceram-

ic capacitors are recommended. Ceramic capacitor

materials such as X7R and X5R type are a good

choice for this application.

Over-Voltage Protection

An over-voltage event is defined as a condition

where the voltage on the BAT pin exceeds the max-

imum battery charge voltage and is set by the over-

voltage protection threshold (VOVP). If an over-volt-

age condition occurs, the AAT3689 charge control

will shut down the device until voltage on the BAT

pin drops below the over-voltage protection thresh-

old (VOVP). The AAT3689 will resume normal charg-

ing operation after the over-voltage condition is

removed. During an over-voltage event, the STAT

LEDs will report a system fault.

Over-Temperature Shutdown

The AAT3689 has a thermal protection control cir-

cuit which will shut down charging functions should

the internal die temperature exceed the preset

thermal limit threshold.

Battery Temperature Fault Monitoring

In the event of a battery over-temperature condi-

tion, the charge control will turn off the internal pass

device. The STAT LEDs will display a system fault.

After the system recovers from a temperature fault,

the device will resume charging operation.

3689.2006.11.1.0

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