AIC1761/1766

BATTERY CHARGE CONTROLLER

SPEC NO: DS-1761-02

ANALOG INTEGRATIONS CORPORATION

www.analog.com.tw

4F, 9 Industry E. 9th Road, Science-based Industrial Park , Hsinchu, Taiwan, R.O.C.

TEL: (8863)577-2500 FAX:(8863)577-2510

10

The LED indicators work as the following table:

LED

PIN

VOUT

PIN

FLASH

PIN

Fast Charge

OFF

ON

ON

Trickle

Charge

ON

OFF

FLASH

Abnormal

OFF

OFF

OFF

LED pin is used in conjunction with VOUT pin

while FLASH pin works alone.

Referring to the APPLICATION EXAMPLES (Fig.

10), the temperature limits beyond where the fast

charge is prohibited can be set by choosing values

for resistors and the thermistor of the thermistor

divider according to the following formula:

limit.

limit.

BATTERY VOLTAGE DIVIDER

To ensure proper operation of the AIC1761/1766,

selection of resistor values for battery voltage di-

vider must meet the following two crucial require-

ments:

1. When the battery pack is disconnected from

the charge circuitry, the voltage of VBT pin

must be higher than 4.0V or lower than 0.5 V to

put the AIC1761/1766 in reset status, where

VOUT and LED pins become high impedance

and FLASH pin (only for 14 pin version) goes to

high level.

2. When the battery pack is connected in normal

operation, the VBT pin voltage must remain in

the range of 0.8V to 3.5V even when the bat-

tery pack voltage reaches to its peak when

near full charge.

Take charging a 8-cell battery pack as an example.

The highest voltage would be 16V when fully

charged if the highest voltage of a fully charged

battery cell is assumed to be 2V. Since the VBT

pin voltage is restricted to be no higher than 3.5V,

the battery voltage divider ratio must be higher

than 3.57 (16V/3.5V -1). In other words, resistor

R14+R13 must be greater than 535K

Ω if R15 is

150K

Ω (refer to Fig. 4). When the battery pack is

disconnected from the charging circuitry the VBT

pin voltage must be higher than 4.0V, dictating

higher than 18.3V (4V x 4.57). Practically, however,

higher than 18.5V in order to ensure proper op-

not meet this requirement, application circuit of Fig.

4 can be adopted to get around this problem.

9012

Q2

9012

Q1

27K

270K

270K

150K

390K

150K

4.7

µF

0.1

µF

0.1

µF

C1

150K

GND

VBT

R3

R2

R14

R13

R5

C2

R15

C3

R7

+

Fig. 4

when being Charged.

CHARGER CIRCUIT DESIGN TIPS

1.

A stable constant charge current is crucial for

reliable precision

−∆V detection by the

AIC1761/1766 since fluctuation of the charge

current can cause fluctuation of the battery

terminal voltage due to battery internal series

resistance, which will likely result in errors

−∆V detection by a properly functioning

AIC1761/1766.

2.

To prevent the AIC1761/1766 from over-

voltage damage, make sure that none of

AIC1761/1766 pins sees any voltage beyond

the supply voltage, which needs to be be-

tween +9V and +18V.