AAT3697 查看數據表（PDF） - Advanced Analogic Technologies

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AAT3697

2A Lithium-Ion/Polymer Battery Charger

Advanced Analogic Technologies 

BatteryManagerTM

RT1 and RT2 for use with PTC Thermistor

Eq. 3: RT1 =

5 ⋅ RTH ⋅ RTC

3 ⋅ (RTH - RTC)

RT2 =

5 ⋅ RTH ⋅ RTC

(2 ⋅ RTH) - (7 ⋅ RTC)

Where RTC is the thermistor’s cold temperature resistance

and RTH is the thermistor’s hot temperature resistance.

See thermistor specifications for information. To ensure

there is no dependence on the input supply changes,

connect the divider between VADP and GND. Disabling the

temperature-monitoring function is achieved by applying

a voltage between VTS1 and VTS2 on the TS pin.

Battery Charge Status Indication

The AAT3697 indicates the status of the battery under

charge with two different systems. First, the device has

two status LED driver outputs. These two LEDs can indi-

cate simple functions such as no battery charge activity,

battery charging, charge complete, and charge fault. The

AAT3697 also provides a bi-directional data reporting

function so that a system microcontroller can interrogate

the DATA pin and read any one of 12 system states.

Status Indicator Display

Simple system charging status states can be displayed

using one or two LEDs in conjunction with the STAT1 and

STAT2 pins on the AAT3697. These two pins are simple

open drain switches used to connect the LED cathodes

to ground. It is not necessary to use both display LEDs

if a user simply wants to have a single lamp to show

“charging” or “not charging.”

This can be accomplished by using the STAT1 pin and a

single LED. Using two LEDs and both STAT pins simply

gives the user more information to the charging states.

Refer to Table 3 for LED display definitions. The LED

anodes should be connected to VADP.

The LEDs should be biased with as little current as nec-

essary to create reasonable illumination; therefore, a

ballast resistor should be placed between the LED cath-

odes and the STAT1/2 pins. LED current consumption

will add to the overall thermal power budget for the

device package, hence it is good to keep the LED drive

current to a minimum. 2mA should be sufficient to drive

most low-cost green or red LEDs. It is not recommended

to exceed 8mA for driving an individual status LED.

1. Flashing rate depends on output capacitance.

PRODUCT DATASHEET

AAT3697

2A Lithium-Ion/Polymer Battery Charger

The required ballast resistor values can be estimated

using the following formulas:

Eq. 4: RB(STAT1/2) =

(VADP - VF(LED))

ILED(STAT1/2)

Example:

Eq. 5: RB(STAT1) =

(5.5V - 2.0V)

2mA

=

1.75kΩ

Note: Red LED forward voltage (VF) is typically 2.0V @

2mA.

Event Description

Charge Disabled or Low Supply

Charge Enabled Without Battery

Battery Charging

Charge Completed

Fault

STAT1

Off

Flash1

On

Off

On

STAT2

Off

Flash1

Off

On

On

Table 3: LED Status Indicator.

Digital Charge Status Reporting

The AAT3697 has a comprehensive digital data reporting

system by use of the DATA pin feature. This function can

provide detailed information regarding the status of the

charging system. The DATA pin is a bi-directional port

which will read back a series of data pulses when the

system microcontroller asserts a request pulse. This sin-

gle strobe request protocol will invoke one of 12 possible

return pulse counts that the system microcontroller can

look up based on the serial report data listed in Table 4.

N

DATA Report Status

1

Chip Over-Temperature Shutdown.

2

Battery Temperature Fault.

3

Over-Voltage Turn Off.

4

Not Used.

5

ADP Watchdog Time-Out in Battery Condition Mode.

6

ADP Battery Condition Mode.

7

ADP Watchdog Time-Out in Constant Current Mode.

8 ADP Thermal Loop Regulation in Constant Current Mode.

9

ADP Constant Current Mode.

10 ADP Watchdog Time-Out in Constant Voltage Mode.

11

ADP Constant Voltage Mode.

12

ADP End of Charging.

23

Data Report Error.

Table 4: Serial Data Report Table.

3697.2008.02.1.3

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