General Description

The MAX8520/MAX8521 are designed to drive thermo-

electric coolers (TECs) in space-constrained optical

modules. Both devices deliver ±1.5A output current

and control the TEC current to eliminate harmful current

surges. On-chip FETs minimize external components

and high switching frequency reduces the size of exter-

nal components.

The MAX8520/MAX8521 operate from a single supply and

bias the TEC between the outputs of two synchronous

buck regulators. This operation allows for temperature

control without “dead zones” or other nonlinearities at

low current. 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.

Both devices feature accurate, individually-adjustable

heating current limit and cooling current limit along with

maximum TEC voltage limit to improve the reliability of

optical modules. An analog output signal monitors the

TEC current. A unique ripple cancellation scheme helps

reduce noise.

The MAX8520 is available in a 5mm x 5mm thin QFN

package and its switching frequency is adjustable up

to 1MHz through an external resistor. The MAX8521 is

also available in a 5mm x 5mm thin QFN as well as

space-saving 3mm x 3mm UCSP™ and 36-bump WLP

(3mm x 3mm) packages, with a pin-selectable switch-

ing frequency of 500kHz or 1MHz.

Applications

SFF/SFP Modules

Fiber Optic Laser Modules

Fiber Optic Network Equipment

ATE

Biotech Lab Equipment

Features

o Low Profile Design

o On-Chip Power MOSFETs

o High-Efficiency Switch-Mode Design

o Ripple Cancellation for Low Noise

o Direct Current Control Prevents TEC Current

Surges

o 5% Accurate Adjustable Heating/Cooling Current

Limits

o 2% Accurate TEC Voltage Limit

o No Dead Zone or Hunting at Low Output Current

o ITEC Monitors TEC Current

o 1% Accurate Voltage Reference

o Switching Frequency up to 1MHz

o Synchronization (MAX8521)

Smallest TEC Power Drivers for Optical

Modules

________________________________________________________________

Maxim Integrated Products

1

Ordering Information

19-2586; Rev 1; 12/08

For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,

or visit Maxim’s website at www.maxim-ic.com.

EVALUATION

KIT

AVAILABLE

PART

TEMP RANGE

PIN-PACKAGE

MAX8520ETP

-40

°C to +85°C 20 Thin QFN-EP* 5mm x 5mm

MAX8521EBX

-40

°C to +85°C 6 x 6 UCSP 3mm x 3mm

MAX8521ETP

-40

°C to +85°C 20 Thin QFN-EP* 5mm x 5mm

MAX8521EWX+

-40

°C to +85°C 36 WLP** 3mm x 3mm

UCSP is a trademark of Maxim Integrated Products, Inc.

INPUT

3V TO 5.5V

COMP

GND

SHDN

ITEC

ON

OFF

TEC CURRENT

MONITOR

CTLI

LX1

PGND1

CS

OS1

OS2

LX2

PGND2

TEC

± 1.5A

REF

CURRENT-

CONTROL

SIGNAL

FREQ

ANALOG /DIGITAL

TEMPERATURE CONTROL

OUTPUT

MAX8521

Typical Operating Circuit

Pin Configurations appear at end of data sheet

+

Denotes a lead(Pb)-free/RoHS-compliant package.

*

EP = Exposed pad.

**

Four center bumps depopulated.