General Description

The MAX1968/MAX1969 are highly integrated and cost-

effective, high-efficiency, switch-mode drivers for Peltier

thermoelectric cooler (TEC) modules. Both devices uti-

lize direct current control to eliminate current surges in

the TEC. On-chip FETs minimize external components

while providing high efficiency. A 500kHz/1MHz switch-

ing frequency and a unique ripple cancellation scheme

reduce component size and noise.

The MAX1968 operates from a single supply and pro-

vides bipolar

±3A output by biasing the TEC between

the outputs of two synchronous buck regulators. Bipolar

operation allows for temperature control without “dead

zones” or other nonlinearities at low load currents. This

arrangement ensures that the control system does not

hunt when the set point is very close to the natural

operating point, requiring a small amount of heating or

cooling. An analog control signal precisely sets the TEC

current. The MAX1969 provides unipolar output up to

6A. Reliability is optimized with settable limits for both

TEC voltage and current, with independently set limits

for heating and cooling current. An analog output also

monitors TEC current.

The MAX1968/MAX1969 are available in a low-profile

28-pin TSSOP-EP package and is specified over the

-40

°C to +85°C temperature range. The thermally-

enhanced TSSOP-EP package with exposed metal pad

minimizes operating junction temperature. An evalua-

tion kit is available to speed designs.

Applications

Fiber Optic Laser Modules

WDM, DWDM Laser Diode Temperature Control

Fiber Optic Network Equipment

EDFA Optical Amplifiers

Telecom Fiber Interfaces

ATE

Biotech Lab Equipment

Features

o Direct Current Control Prevents TEC Current

Surges

o On-Chip Power MOSFETs

o High-Efficiency Switch-Mode Design

o Ripple Cancellation for Low Noise

o No Dead-Zone or Hunting at Low-Output Current

o Adjustable TEC Voltage Limit

o Separately Adjustable Heating and Cooling

Current Limits

o ITEC Output Monitors TEC Current

o 1% Accurate Voltage Reference

o 500kHz/1MHz Switching Frequency

o ±3A Output Current (MAX1968)

o 6A Output Current (MAX1969)

o Thermally Enhanced TSSOP-EP Package

Power Drivers for Peltier TEC Modules

________________________________________________________________ Maxim Integrated Products

1

Ordering Information

19-2447; Rev 0; 4/02

For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at

1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.

EVALUATION

KIT

AVAILABLE

PART

TEMP RANGE

PIN-PACKAGE

MAX1968EUI

-40°C to +85°C

28 TSSOP-EP*

MAX1969EUI

-40°C to +85°C

28 TSSOP-EP*

Typical Operating Circuit

PGND1

PGND2

CTLI

COMP

LX2

LX1

GND

MAX1968

OS2

CS

OS2

TEC

3V TO

5.5V

TEC

CURRENT-

CONTROL

SIGNAL

Pin Configuration and Functional Diagram appear at end

of datasheet.

*EP = exposed paddle