For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800.

For small orders, phone 1-800-835-8769.

General Description

The MAX1669 fan controller includes a precise digital

thermometer that reports the temperature of a remote

sensor. The remote sensor is a diode-connected transis-

tor—typically a low-cost, easily mounted 2N3906 PNP

type—replacing conventional thermistors or thermocou-

ples. Remote accuracy is ±3°C for transistors from multi-

ple manufacturers, with no calibration needed. The

MAX1669 has an independent fan controller with a low-

current logic output requiring external power compo-

nents to interface to a DC brushless fan. The fan

controller has two modes of operation: a low-frequency

(20Hz to 160Hz) PWM mode intended for driving the fan

motor, or a high-impedance DAC output that generates

a variable DC control voltage. In PWM mode, the FAN

frequency can be synchronized to an external clock.

Other key features include general-purpose inputs/out-

puts (GPIOs) for fan presence detection and a thermo-

stat output intended as a fan override signal in case the

host system loses the ability to communicate. The inter-

nal ADC has a wide input voltage range and gives

overrange readings when too large an input voltage is

applied. Other error-checking includes temperature

out-of-range indication and diode open/short faults.

The MAX1669 is available in a space-saving 16-pin

QSOP package that allows it to fit adjacent to the

SLOT1 connector.

Applications

Desktop Computers

Notebook Computers

Servers

Workstations

Features

o Measures Remote CPU Temperature

o No Calibration Required

o 20Hz to 160Hz PWM Output for Fan

o PWM Frequency Sync Input (260kHz)

o Flexible Fan Interface: Linear or PWM

o SMBus 2-Wire Serial Interface

o Programmable Under/Overtemperature Alarms

o ALERT Latched Interrupt Output

o OVERT Thermostat Output

o Two GPIO Pins

o Write-Once Configuration Protection

o Supports SMBus Alert Response

o ±3°C Temperature Accuracy (-40°C to +125°C,

remote)

o 3µA Standby Supply Current

o +3V to +5.5V Supply Range

o Small 16-Pin QSOP Package

Fan Controller and Remote Temperature Sensor

with SMBus Serial Interface

________________________________________________________________ Maxim Integrated Products

1

16

15

14

13

12

11

10

9

1

2

3

4

5

6

7

8

I/O1

OVERT

ALERT

SMBDATA

SMBCLK

PGND

FAN

SYNC

TOP VIEW

MAX1669

QSOP

I/O2

ADD0

AGND

ADD1

ADD2

DXN

DXP

19-1574; Rev 0; 1/00

PART

MAX1669EEE

-40°C to +85°C

TEMP. RANGE

PIN-PACKAGE

16 QSOP

Pentium is a registered trademark of Intel Corp.

Pin Configuration

Ordering Information

Typical Operating Circuit appears at end of data sheet.