REV. 0

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a

ADP3810/ADP3811

One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.

Tel: 617/329-4700

World Wide Web Site: http://www.analog.com

Fax: 617/326-8703

© Analog Devices, Inc., 1996

Secondary Side, Off-Line

Battery Charger Controllers

FUNCTIONAL BLOCK DIAGRAM

ADP3810/

ADP3811

COMP

OUT

GND

1.5M

Ω

80k

Ω

UVLO

GM

GM1

UVLO

UVLO

R1

R2

ADP3810

ONLY

GM2

FEATURES

Programmable Charge Current

High Precision Battery Voltage Limit

Precision 2.000 V Reference

Low Voltage Drop Current Sense: 300 mV Full Scale

Full Operation in Shorted and Open Battery Conditions

Drives Diode-Side of Optocoupler

Wide Operating Supply Range: 2.7 V to 16 V

Undervoltage Lockout

SO-8 Package

ADP3810

Internal Precision Voltage Divider for Battery Sense

Four Final Battery Voltage Options Available: 4.2 V,

8.4 V, 12.6 V, 16.8 V

ADP3811

Adjustable Final Battery Voltage

APPLICATIONS

Battery Charger Controller for:

LiIon Batteries (ADP3810)

NiCad, NiMH Batteries (ADP3811)

GENERAL DESCRIPTION

The ADP3810 and ADP3811 combine a programmable current

limit with a battery voltage limit to provide a constant current,

constant voltage battery charger controller. In secondary side,

off-line applications, the output directly drives the diode side of

an optocoupler to give isolated feedback control of a primary

sion 2.0 V reference, a control input buffer, an Undervoltage

Lock Out (UVLO) comparator, an output buffer and an over-

voltage comparator.

The current limit amplifier senses the voltage drop across an

external sense resistor to control the average current for charg-

ing a battery. The voltage drop can be adjusted from 25 mV

to 300 mV, giving a charging current limit from 100 mA to

1.2 amps with a 0.25

Ω sense resistor. An external dc voltage

is high impedance, a filtered PWM output can be used to set

the voltage.

As the battery voltage approaches its voltage limit, the voltage

sense amplifier takes over to maintain a constant battery volt-

age. The two amplifiers essentially operate in an “OR” fash-

ion. Either the current is limited, or the voltage is limited.

The ADP3810 has internal thin-film resistors that are trimmed

to provide a precise final voltage for LiIon batteries. Four volt-

age options are available, corresponding to 1-4 LiIon cells as

follows: 4.2 V, 8.4 V, 12.6 V and 16.8 V.

The ADP3811 omits these resistors allowing any battery volt-

age to be programmed with external resistors.