General Description

The MAX6684 is an integrated fan-failure detector that

detects when a fan exhibits excessive underspeed or a

locked rotor. This device is especially well suited for criti-

cal systems where no fan control, or simple on/off control

is desired. The MAX6684 detects fan failure by evaluat-

ing fluctuations in current at the low side of the fan; no

tachometer signal is necessary. The output of the device,

FAIL, is an active-low, open-drain alarm. The MAX6684

can also be used to switch the fan on or off, based on

the state of a logic-level input, OFF. This device can be

used with fans rated at up to 24V and 250mA. The

MAX6684 is available in an 8-pin SO package, and is

specified for operation from -40°C to +85°C.

Applications

Desktop PCs

Notebooks

Networking Equipment

Telecommunications

Industrial Applications

Features

o Dedicated Fan-Failure Detector

o Works with Ordinary 2-Wire Fans

o No Fan Tachometer Output Required

o No Software Development Required

o No Analog Circuit Design Required

o Logic-Level Fan Driver Control

o Works with Fans Rated Up to 24V/250mA

Fan-Failure Detector with Integrated

Power Switch

________________________________________________________________ Maxim Integrated Products

1

FC+

FC-

1

2

8

7

PGND

OFF

FAIL

GND

SENSE

SO

TOP VIEW

3

4

6

5

MAX6684

Pin Configuration

Ordering Information

MAX6684

OFF

SENSE

12V

PGND

GND

FC+

10k

Ω

FC-

3.3V

1

µF

0.1

µF

0.1

µF

FAIL

Typical Operating Circuit

19-2306; Rev 0; 1/02

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.

PART

TEMP RANGE

PIN-PACKAGE

MAX6684ESA

-40°C to +85°C

8 SO