19-3304; Rev 1; 4/06
SMBus-Compatible Temperature Monitor with
Automatic PWM Fan-Speed Controller
General Description
Features
The MAX6641 temperature sensor and fan controller
accurately measures the temperature of its own die and
the temperature of a remote pn junction. The device
reports temperature values in digital form using a 2-wire
serial interface. The remote pn junction is typically the
emitter-base junction of a common-collector pnp on a
CPU, FPGA, or ASIC.
♦ Tiny 3mm x 5mm µMAX Package
♦ Thermal Diode Input
♦ Local Temperature Sensor
♦ Open-Drain PWM Output for Fan Drive
♦ Programmable Fan Control Characteristics
♦ Automatic Fan Spin-Up Ensures Fan Start
The 2-wire serial interface accepts standard System
Management Bus (SMBus)TM write byte, read byte,
send byte, and receive byte commands to read the
temperature data and program the alarm thresholds.
The temperature 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
maximum cooling when power dissipation increases.
The device also features an over-temperature alarm
output to generate interrupts, throttle signals, or shut
down signals. The MAX6641 operates from supply volt-
ages in the 3.0V to 5.5V range and typically consumes
500µA of supply current.
♦ ±±1C ꢀemote Temperature Accuracy ꢁ(+61C to
(±451C)
♦ Controlled ꢀate of Change Ensures Unobtrusive
Fan-Speed Adjustments
♦ Temperature Monitoring Begins at Power-On for
Fail-Safe System Protection
♦ OT Output for Throttling or Shutdown
The MAX6641 is available in a slim 10-pin µMAX® pack-
age and is available over the -40°C to +125°C automo-
tive temperature range.
Ordering Information
PIN-
SMBus
PKG
PAꢀT
PACKAGE
ADDꢀESS
CODE
Applications
Desktop Computers
Notebook Computers
Workstations
MAX6641AUB90
MAX6641AUB92
MAX6641AUB94
MAX6641AUB96
10 µMAX
10 µMAX
10 µMAX
10 µMAX
1001 000x
1001 001x
1001 010x
1001 011x
U10-2
U10-2
U10-2
U10-2
Note: All devices are specified over the -40°C to +125°C tem-
perature range.
Servers
Networking Equipment
Industrial
Pin Configuration
TOP VIEW
Typical Application Circuit appears at end of data sheet.
I.C.
DXN
DXP
GND
OT
1
2
3
4
5
10 PWMOUT
9
8
7
6
V
CC
MAX6641
SMBDATA
SMBCLK
I.C.
µMAX
µMAX is a registered trademark of Maxim Integrated Products, Inc.
SMBus is a trademark of Intel Corp.
________________________________________________________________ Maxim Integrated Products
±
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.