_______________General Description

The MAX712/MAX713 fast charge Nickel Metal Hydride

(NiMH) and Nickel Cadmium (NiCd) batteries from a DC

source at least 1.5V higher than the maximum battery

voltage. 1 to 16 series cells can be charged at rates up

to 4C. A voltage-slope detecting analog-to-digital convert-

er, timer, and temperature window comparator determine

charge completion. The MAX712/MAX713 are powered

by the DC source via an on-board +5V shunt regulator.

They draw a maximum of 5

µA from the battery when not

charging. A low-side current-sense resistor allows the

battery charge current to be regulated while still

supplying power to the battery’s load.

The MAX712 terminates fast charge by detecting zero

voltage slope, while the MAX713 uses a negative

voltage-slope detection scheme. Both parts come in 16-

pin DIP and SO packages. An external power PNP tran-

sistor, blocking diode, three resistors, and three

capacitors are the only required external components.

For high-power charging requirements, the MAX712/

MAX713 can be configured as a switch-mode battery

charger that minimizes power dissipation. Two evaluation

kits are available: Order the MAX712EVKIT-DIP for quick

evaluation of the linear charger, and the MAX713EVKIT-

SO to evaluate the switch-mode charger.

________________________Applications

Battery-Powered Equipment

Laptop, Notebook, and Palmtop Computers

Handy-Terminals

Cellular Phones

Portable Consumer Products

Portable Stereos

Cordless Phones

____________________________Features

o Fast Charge NiMH or NiCd Batteries

o Voltage Slope, Temperature, and Timer

Fast-Charge Cutoff

o Charge 1 to 16 Series Cells

o Supply Battery’s Load while Charging (Linear Mode)

o Fast Charge from C/4 to 4C Rate

o C/16 Trickle-Charge Rate

o Automatically Switch from Fast to Trickle Charge

o Linear or Switch-Mode Power Control

o 5µA Max Drain on Battery when Not Charging

o 5V Shunt Regulator Powers External Logic

NiCd/NiMH Battery

Fast-Charge Controllers

________________________________________________________________

Maxim Integrated Products

1

MAX712

MAX713

THI

R2

150

Ω

R3

68k

Ω

R4

22k

Ω

R1

10

µF

C4

0.01

µF

C1

1

µF

C3

10

µF

C2

0.01

µF

DRV

Q1

2N6109

DC IN

WALL

CUBE

SEE FIGURE 19 FOR SWITCH-MODE CHARGER CIRCUIT.

D1

1N4001

BATTERY

V+

VLIMIT

BATT+

REF

TEMP

BATT- TLO GND

CC

LOAD

__________Typical Operating Circuit

16

15

14

13

12

11

10

9

1

2

3

4

5

6

7

8

REF

V+

DRV

GND

BATT-

CC

PGM3

PGM2

VLIMIT

BATT+

PGM0

PGM1

THI

TLO

TEMP

FASTCHG

TOP VIEW

MAX712

MAX713

DIP/SO

__________________Pin Configuration

19-0100; Rev 3; 1/97

PART

MAX712CPE

MAX712CSE

MAX712C/D

0°C to +70°C

0°C to +70°C

0°C to +70°C

TEMP. RANGE

PIN-PACKAGE

16 Plastic DIP

16 Narrow SO

Dice*

EVALUATION

KIT MANUALS

FOLLOW

DATA

SHEET

______________Ordering Information

Ordering Information continued at end of data sheet.

*

Contact factory for dice specifications.

**

Contact factory for availability and processing to MIL-STD-883.

For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800

MAX712EPE

MAX712ESE

MAX712MJE

-55°C to +125°C

-40°C to +85°C

-40°C to +85°C

16 Plastic DIP

16 Narrow SO

16 CERDIP**