_______________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 5µA 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

♦ Fast Charge NiMH or NiCd Batteries

♦ Voltage Slope, Temperature, and Timer

Fast-Charge Cutoff

♦ Charge 1 to 16 Series Cells

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

♦ Fast Charge from C/4 to 4C Rate

♦ C/16 Trickle-Charge Rate

♦ Automatically Switch from Fast to Trickle Charge

♦ Linear or Switch-Mode Power Control

♦ 5µA Max Drain on Battery when Not Charging

♦ 5V Shunt Regulator Powers External Logic

MAX712/MAX713

NiCd/NiMH Battery

Fast-Charge Controllers

________________________________________________________________

Maxim Integrated Products

MAX712

MAX713

THI

R2

150Ω

R3

68kΩ

R4

22kΩ

10µF

C4

0.01µF

C1

1µF

C3

10µF

C2

0.01µF

DRV

Q1

2N6109

DC IN

WALL 

CUBE

SEE FIGURE 19 FOR SWITCH-MODE CHARGER CIRCUIT.

D1

1N4001

BATTERY

SENSE

V+

VLIMIT

BATT+

REF

TEMP

BATT- TLO GNDCC

LOAD



__________Typical Operating Circuit

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

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**

MAX712/MAX713

NiCd/NiMH Battery

Fast-Charge Controllers

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

ELECTRICAL CHARACTERISTICS

V+

= 10mA, T

= T

MIN

to T

MAX

, unless otherwise noted. Refer to

Typical Operating Circuit

. All measurements are with respect to

BATT-, not GND.)

Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional

operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to

absolute maximum rating conditions for extended periods may affect device reliability.

V+ to BATT-.................................................................-0.3V, +7V

BATT- to GND........................................................................±1V

BATT+ to BATT-

Power Not Applied............................................................±20V

With Power Applied................................The higher of ±20V or

±2V x (programmed cells)

DRV to GND ..............................................................-0.3V, +20V

FASTCHG to BATT-...................................................-0.3V, +12V

All Other Pins to GND......................................-0.3V, (V+ + 0.3V)

V+ Current.........................................................................100mA

DRV Current......................................................................100mA

REF Current.........................................................................10mA

Continuous Power Dissipation (T

= +70°C)

Plastic DIP (derate 10.53mW/°C above +70°C............842mW

Narrow SO (derate 8.70mW/°C above +70°C .............696mW

CERDIP (derate 10.00mW/°C above +70°C ................800mW

Operating Temperature Ranges

MAX71_C_E .......................................................0°C to +70°C

MAX71_E_E .................................................... -40°C to +85°C

MAX71_MJE ................................................. -55°C to +125°C

Storage Temperature Range .............................-65°C to +150°C

Lead Temperature (soldering, 10sec) .............................+300°C

DRV

= 10V

V+ = 0V, BATT+ = 17V

PGM3 = BATT-

5mA < I

V+

< 20mA

PGM3 = REF

PGM3 = open

PGM3 = V+

0V < TEMP < 2V, TEMP voltage rising

LIMIT

= V+

Per cell

PGM0 = PGM1 = BATT-, BATT+ = 30V

1.2V < V

LIMIT

< 2.5V, 5mA < I

DRV

< 20mA,

PGM0 = PGM1 = V+

0mA < I

REF

< 1mA

CONDITIONS

mA30DRV Sink Current

%-1.5 1.5

Battery-Voltage to Cell-Voltage

Divider Accuracy

%-15 15Timer Accuracy

26.0 31.3 38.0

Trickle-Charge VSENSE

12.0 15.6 20.0

4.5 7.8 12.0

1.5 3.9 7.0

mV225 250 275Fast-Charge VSENSE

V1.6 1.65 1.7Internal Cell Voltage Limit

mV-30 30VLIMIT Accuracy

µA-1 1THI, TLO, TEMP, VLIMIT Input Bias Current

µA5BATT+ Leakage

mA5I

V+

(Note 1)

V4.5 5.5V+ Voltage

mV-10 10THI, TLO Offset Voltage (Note 2)

V02THI, TLO, TEMP Input Range

V1.25 2.50External VLIMIT Input Range

V0.35 0.50Undervoltage Lockout

kΩ30BATT+ Resistance with Power On

µF0.5C1 Capacitance

nF5C2 Capacitance

V1.96 2.04REF Voltage

UNITSMIN TYP MAXPARAMETER

MAX712

MAX713

mV/t

per cell

Voltage-Slope Sensitivity (Note 3)

-2.5

ELECTRICAL CHARACTERISTICS (continued)

+ = 10mA, T

= T

MIN

to T

MAX

, unless otherwise noted. Refer to

Typical Operating Circuit

. All measurements are with respect to

BATT-, not GND.)

Note 1: The MAX712/MAX713 are powered from the V+ pin. Since V+ shunt regulates to +5V, R1 must be small enough to allow at

least 5mA of current into the V+ pin.

Note 2: Offset voltage of THI and TLO comparators referred to TEMP.

Note 3: t

is the A/D sampling interval (Table 3).

Note 4: This specification can be violated when attempting to charge more or fewer cells than the number programmed. To ensure

proper voltage-slope fast-charge termination, the (maximum battery voltage) ÷ (number of cells programmed) must fall

within the A/D input range.

MAX712/MAX713

NiCd/NiMH Battery

Fast-Charge Controllers

_______________________________________________________________________________________ 3

Battery voltage ÷ number of cells programmed

FASTCHG

= 10V

FASTCHG

= 0.4V

CONDITIONS

V1.4 1.9A/D Input Range (Note 4)

µA10

FASTCHG High Current

mA2

FASTCHG Low Current

UNITSMIN TYP MAXPARAMETER

__________________________________________Typical Operating Characteristics

= +25°C, unless otherwise noted.)



100k

1M10k 10M

CURRENT-SENSE AMPLIFIER

FREQUENCY RESPONSE (with 15pF)

-20

FREQUENCY (Hz)

GAIN (dB)

PHASE (DEGREES)

-10

-120

-80

-40

C2 = 15pF

FASTCHG = 0V

OUT



CURRENT-

SENSE 

AMP

BATT-

GND

MAX712/13 LOG1

-10

-20

10 1k

CURRENT-SENSE AMPLIFIER

FREQUENCY RESPONSE (with 10nF)

-80

-120

-40

FREQUENCY (Hz)

GAIN (dB)

PHASE (DEGREES)

100 10k



C2 = 10nF

FASTCHG = 0V

MAX712/13 LOG2

100

0.1

1.95 1.97 2.01 2.05

CURRENT ERROR-AMPLIFIER

TRANSCONDUCTANCE

VOLTAGE ON CC PIN (V)

DRV PIN SINK CURRENT(mA)

1.99 2.03

FASTCHG = 0V, V+ = 5V

MAX712/13 LOG3

5.8

4.8

060

SHUNT-REGULATOR VOLTAGE

vs. CURRENT

5.6

CURRENT INTO V+ PIN (mA)

V+ VOLTAGE (V)

5.2

5.0

10 20 50

5.4

4.0

4.4

4.2

4.6

DRV NOT SINKING CURRENT

DRV SINKING CURRENT

MAX712/13 LOG4

1.0

060

ALPHA THERMISTOR PART No. 13A1002

STEINHART-HART INTERPOLATION

1.6

BATTERY TEMPERATURE(°C)

TEMP PIN VOLTAGE (V)

BATTERY THERMISTOR RESISTANCE (kΩ)

1.4

1.2

10 20 50

0.2

0.6

0.4

0.8

Part #	MAX713CSE
Description	NICD/NIMH BATTERY FAST-CHARGECONTROLLER -
Category	IC
Availability	In Stock
Qty	72

Qty	Price
1 - 15	$5.22346
16 - 30	$4.15503
31 - 45	$3.91760
46 - 60	$3.64060
61 +	$3.24488

Manufacturer	Available	Qty
MAXIM Date Code: 0011	Freelance Stock: 41 Ships Immediately
MAXIM Date Code: 1028	Freelance Stock: 31 Ships Immediately

MAX713CSE

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