AAT3697 Ver la hoja de datos (PDF) - Advanced Analogic Technologies

Número de pieza

componentes Descripción

Fabricante

AAT3697

2A Lithium-Ion/Polymer Battery Charger

Advanced Analogic Technologies 

BatteryManagerTM

Application Information

Adapter Power Input

Constant current charge levels up to 2.0A may be pro-

grammed by the user when powered from a sufficient

input power source. The AAT3697 will operate from the

adapter input over a 4.0V to 5.5V range.

The constant current fast charge current for the adapter

input is set by the RSET resistor connected between the

ADPSET pin and ground. Refer to Table 1 for recom-

mended RSET values for a desired constant current charge

level. The presence of voltage on the adapter input is

indicated by the ADPP# pin function. This indicator pin

uses an internal open drain device that will pull the

ADPP# pin low when voltage is detected on the ADP pin.

The precise charging function of the AAT3697 may be

read from the DATA pin and/or status LEDs. Please refer

to the Battery Charge Status Indication discussion for

further details on data reporting.

Thermal Loop Control

Due to the integrated nature of the linear charging con-

trol pass device for the adapter input, a special thermal

loop control system has been employed to maximize

charging current under all operating conditions. The

thermal management system measures the internal cir-

cuit die temperature and reduces the fast charge current

when the device exceeds a preset internal temperature

control threshold. Once the thermal loop control becomes

active, the fast charge current is initially reduced by a

factor of 0.44.

The initial thermal loop current can be estimated by the

following equation:

Eq. 1: ITLOOP = ICH · 0.44

The thermal loop control re-evaluates the circuit die tem-

perature in 330ms intervals and adjusts the fast charge

current back up in small steps to the full fast charge cur-

rent level or until an equilibrium current is discovered

and maximized for the given ambient temperature condi-

tion. The thermal loop controls the system charge level;

therefore, the AAT3697 will always provide the highest

level of constant current in the fast charge mode possible

for any given ambient temperature condition.

PRODUCT DATASHEET

AAT3697

2A Lithium-Ion/Polymer Battery Charger

Adapter Input Charge Inhibit and Resume

The AAT3697 has a UVLO and power on reset feature so

that the charger will suspend charging and shut down if

the input supply to the adapter pin drops below the

UVLO threshold. When power is re-applied to the adapt-

er pin or the UVLO conditions recovers, the system

charge control will assess the state of charge on the bat-

tery cell and will automatically resume charging in the

appropriate mode for the condition of the battery.

Enable / Disable

The AAT3697 provides an enable function to control the

charger IC on and off. The enable (EN) pin is active high.

When pulled to a logic low level, the AAT3697 will be shut

down and forced into the sleep state. Charging will be

halted regardless of the battery voltage or charging state.

When the device is re-enabled, the charge control circuit

will automatically reset and resume charging functions

with the appropriate charging mode based on the battery

charge state and measured cell voltage on the BAT pin.

Programming Charge Current

The fast charge constant current charge level is user

programmed with a set resistor placed between the

ADPSET pin and ground. The accuracy of the fast charge,

as well as the preconditioning trickle charge current, is

dominated by the tolerance of the set resistor used. For

this reason, a 1% tolerance metal film resistor is recom-

mended for the set resistor function.

Fast charge constant current levels from 50mA to 2.0A

can be set by selecting the appropriate resistor value

from Table 1.

ICH (mA)

100

200

300

400

500

600

700

800

900

1000

RSET (kΩ)

84.5

43.2

28.0

21.0

16.9

13.3

11.5

10.2

90.9

8.06

ICH (mA)

1100

1200

1300

1400

1500

1600

1700

1800

1900

2000

RSET (kΩ)

7.32

6.65

6.04

5.62

5.36

4.87

4.53

4.22

3.92

3.65

Table 1: Recommended RSET Values.

3697.2008.02.1.3

www.analogictech.com

11

Share Link: