Rainbow Electronics MAX6640 - Manual

General Description
The MAX6640 monitors its own temperature and one
external diode-connected transistor or the temperatures
of two external diode-connected transistors, typically
available in CPUs, FPGAs, or GPUs. 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. Temperature data
can be read at any time over the SMBus, and three pro-
grammable alarm outputs can be used to generate
interrupts, throttle signals, or overtemperature shut-
down signals.
The temperature data is also used by the internal dual
PWM fan-speed controller to adjust the speed of up to
two cooling fans, thereby minimizing noise when the
system is running cool, but providing maximum cooling
when power dissipation increases. Speed control is
accomplished by tachometer feedback from the fan, so
that the speed of the fan is controlled, not just the PWM
duty cycle. Accuracy of speed measurement is ±4%.
The MAX6640 is available in 16-pin QSOP and 16-pin
TQFN 5mm x 5mm packages. 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
♦ 1°C Remote Temperature Accuracy (+60°C to
+100°C)
♦ Two PWM Outputs for Fan Drive (Open Drain; can
be Pulled Up to +13.5V)
♦ Programmable Fan-Control Characteristics
♦ Automatic Fan Spin-Up Ensures Fan Start
♦ Controlled Rate-of-Change Ensures Unobtrusive
Fan-Speed Adjustments
♦ ±4% Fan-Speed Measurement Accuracy
♦ Temperature Monitoring Begins at POR for Fail-
Safe System Protection
♦ OT and THERM Outputs for Throttling or
Shutdown
♦ Measures Temperatures Up to +150°C
♦ Tiny 5mm x 5mm 16-Pin TQFN and QSOP
Packages
MAX6640
2-Channel Temperature Monitor with Dual
Automatic PWM Fan-Speed Controller
________________________________________________________________ Maxim Integrated Products 1
Ordering Information
19-3344; Rev 0; 8/04
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.
PART
OPERATING
RANGE
MEASUREMENT
RANGE
PIN-
PACKAGE
MAX6640AEE
-40 °C to
+125 °C
0°C to +150°C 16 QSOP
MAX6640ATE
-40 °C to
+125 °C
0°C to +150°C
16 TQFN
(5mm x
5mm)
16
15
14
13
12
11
10
9
1
2
3
4
5
6
7
8
PWM1 SCL
SDA
V CC
DXP2
DXN
GND
DXP1
TOP VIEW
MAX6640
QSOP
TACH1
PWM2
TACH2
V CC
FANFAIL
THERM
OT
ALERT
PWM2 1
TACH2 2
3
4
FANFAIL
THERM
12
V
CC
11
10
9
DXP2
DXN
5
V
CC
6 7 8
GND
DXP1
OT
16
PWM1
15 14 13
SDA SCL TACH1
ALERT
MAX6640
*CONNECT EXPOSED
PADDLE TO GND
5mm x 5mm THIN QFN
Pin Configurations
SMBus is a trademark of Intel Corp.
Typical Application Circuit appears at end of data sheet.