General Description

The MAX6678 monitors its own temperature and the

temperatures of two external diode-connected transis-

tors, which typically reside on the die of a CPU or other

integrated circuit. The device reports temperature values

in digital form using a 2-wire serial interface. The

MAX6678 provides a programmable alarm output to gen-

erate interrupts, throttle signals, or overtemperature shut-

down signals.

The 2-wire serial interface accepts standard System

byte, and receive byte commands to read the tempera-

ture data and program the alarm thresholds. The tem-

perature data controls a PWM output signal to adjust

the speed of a cooling fan, thereby minimizing noise

when the system is running cool, but providing maxi-

mum cooling when power dissipation increases.

Five GPIO pins provide additional flexibility. The GPIO

power-up states are set by connecting the GPIO preset

The MAX6678 is available in a 20-pin QSOP package

and a 5mm x 5mm thin QFN package. It operates from

3.0V to 5.5V and consumes just 500µA of supply current.

Applications

Desktop Computers

Notebook Computers

Workstations

Servers

Networking Equipment

Features

♦ Two Thermal-Diode Inputs

♦ Local Temperature Sensor

♦ Five GPIO Input/Outputs

♦ Two PWM Outputs for Fan Drive (Open Drain; May

Be Pulled Up to +5V)

♦ Programmable Fan-Control Characteristics

♦ Automatic Fan Spin-Up Ensures Fan Start

♦ Controlled Rate of Change Ensures Unobtrusive

Fan-Speed Adjustments

♦ 1°C Remote Temperature Accuracy (+60°C to

+145°C)

♦ Temperature Monitoring Begins at POR for Fail-

Safe System Protection

♦ OT Output for Throttling or Shutdown

♦ Four Versions Available, Each with a Different

Address

♦ 5mm x 5mm TQFN Package

2-Channel Temperature Monitor with Dual Automatic

PWM Fan-Speed Controller and Five GPIOs

________________________________________________________________ Maxim Integrated Products

1

20

19

18

17

16

13

12

11

14

15

GPIO3

GPIO2

GPIO1

OT

PRESET0

4

3

2

1

PRESET4

GPIO4

SMBCLK

SMBDATA

5

DXP1

678

9

10

MAX6678

*CONNECT EXPOSED

PADDLE TO GND

TOP VIEW

5mm x 5mm THIN QFN

Pin Configurations

Ordering Information

19-3306; Rev 0; 5/04

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.

*EP = Exposed paddle.

PART

TEMP RANGE

PIN-

PACKAGE

SMBus

ADDRESS

MAX6678AEP90

-40°C to +125°C

20 QSOP

1001000

MAX6678AEP92

-40°C to +125°C

20 QSOP

1001001

MAX6678AEP94

-40°C to +125°C

20 QSOP

1001010

MAX6678AEP96

-40°C to +125°C

20 QSOP

1001011

MAX6678ATP90

-40°C to +125°C

20 Thin

QFN-EP*

1001000

MAX6678ATP92

-40°C to +125°C

20 Thin

QFN-EP*

1001001

MAX6678ATP94

-40°C to +125°C

20 Thin

QFN-EP*

1001010

MAX6678ATP96

-40°C to +125°C

20 Thin

QFN-EP*

1001011

SMBus is a trademark of Intel Corp.

Pin Configurations continued at end of data sheet.

Typical Operating Circuit appears at end of data sheet.