AAT3682

DATA SHEET

Li-Ion/Polymer Linear Battery Charger

12

Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com

201884B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • April 25, 2012

Sleep / Charge Complete

Temp., OC, OV Fault

Battery Conditioning

Constant Current Mode

Constant Voltage Mode

HI / HI / HI / HI

LO / LO / HI / HI

LO / LO / LO / LO

LO / HI / HI / HI

LO / LO / LO / HI

Charge Status

Output Status

STAT Level

Figure 4: Microcontroller Interface Logic Output.

High-Speed Data Reporting

An optional system microcontroller interface can be

enabled by pulling the T2X pin up to 4.5V to 5.5V during

the power-up sequence. The T2X pin should be pulled

high with the use of a 100k resistor. If the input supply

TTL level circuit, it may not be pulled higher than 5.5V

without risk of damage to the device.

When the high-speed data report feature is enabled, the

STAT output periods are sped up to 40μs, making the

total status word 160μs in length. See Figure 4 below.

An additional feature is the Output Status for the Battery

Not Detected state. When the AAT3682 senses there is

no battery connected to the BAT pin, the STAT pin cycles

for two periods, then remains off for two periods. When

in high-speed data reporting, the AAT3682 will only

trickle charge at the 2X trickle charge level. This is

because the T2X pin is pulled high to enable the high-

speed data reporting. A status display LED may not be

connected to the STAT pin when the high-speed data

reporting is being utilized. If both display modes are

required, the display LED must be switched out of the

circuit before the T2X pin is pulled high. Failing to do so

could cause problems with the high-speed switching con-

trol circuits internal to the AAT3682.

Charge Complete LED Status Mode

A simplified LED status can be obtained by configuring

the AAT3682 for high-speed data reporting mode (T2X

tied to VCC) and installing a 0.047μF capacitor from the

STAT pin to the VSS pin (see Figure 5). In this configura-

tion, the LED will be illuminated for all modes except the

Sleep/Charge Complete mode. In addition, the T2X input

must be tied to VCC through a 100k resistor. In this

mode, the trickle charge current will be 1.8X the normal

trickle charge level. To reset the trickle charge current to

the 1X level, the TS input must be temporarily toggled

low. Removing C3 forces the LED status to gradually dim

as the battery becomes fully charged (see Figure 5).

Protection Circuitry

The AAT3682 is a highly integrated battery management

system IC including several protection features. In addi-

tion to battery temperature monitoring, the IC constant-

ly monitors for over-current and over-voltage conditions;

if an over-current situation occurs, the AAT3682 latches

off the pass device to prevent damage to the battery or

the system, and enters shutdown mode until the over-

current event is terminated. An over-voltage condition is

defined as a condition where the voltage on the BAT pin

exceeds the maximum battery charge voltage. If an over-

voltage condition occurs, the IC turns off the pass device

until voltage on the BAT pin drops below the maximum

battery charge constant voltage threshold. The AAT3682

will resume normal operation after the over-current or

over-voltage condition is removed. During an over-cur-

rent or over-voltage event, the STAT will report a FAULT

signal. In the event of a battery over-temperature condi-

tion, the IC will turn off the pass device and report a

FAULT signal on the STAT pin. After the system recovers

from a temperature fault, the IC will resume operation in

the 1X trickle charge mode to prevent damage to the

system in the event a defective battery is placed under

charge. Once the battery voltage rises above the trickle

charge to constant current charge threshold, the IC will

resume the constant current mode.