MAX6678 Datasheet, PDF (1/19 Pages) Maxim Integrated Products – 2-Channel Temperature Monitor with Dual Automatic PWM Fan-Speed Controller and Five GPIOs

19-3306; Rev 0; 5/04
2-Channel Temperature Monitor with Dual Automatic
PWM Fan-Speed Controller and Five GPIOs
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
Management Bus (SMBus)^™ write byte, read byte, send
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
inputs to ground or V_CC.
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
SMBus is a trademark of Intel Corp.
Pin Configurations
TOP VIEW
20 19 18 17 16
SMBDATA 1
SMBCLK 2
GPIO4 3
PRESET4 4
DXP1 5
MAX6678
*CONNECT EXPOSED
PADDLE TO GND
15 OT
14 GPIO1
13 GPIO2
12 GPIO3
11 PRESET0
6 7 8 9 10
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
Ordering Information
PART
TEMP RANGE ^PIN-
PACKAGE
MAX6678AEP90
MAX6678AEP92
MAX6678AEP94
MAX6678AEP96
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
20 QSOP
20 QSOP
20 QSOP
20 QSOP
MAX6678ATP90 -40°C to +125°C ^{20 Thin}
QFN-EP*
MAX6678ATP92 -40°C to +125°C ^{20 Thin}
QFN-EP*
MAX6678ATP94 -40°C to +125°C ^{20 Thin}
QFN-EP*
MAX6678ATP96
-40°C to +125°C
20 Thin
QFN-EP*
*EP = Exposed paddle.
SMBus
ADDRESS
1001000
1001001
1001010
1001011
1001000
1001001
1001010
1001011
5mm x 5mm THIN QFN
Pin Configurations continued at end of data sheet.
Typical Operating Circuit appears at end of data sheet.
________________________________________________________________ Maxim Integrated Products 1
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