Rainbow Electronics MAX6678 - Manual

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
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
MAX6678
2-Channel Temperature Monitor with Dual Automatic
PWM Fan-Speed Controller and Five GPIOs
________________________________________________________________ Maxim Integrated Products 1
20 19 18 17
PRESET3 PWMOUT2 V CC PWMOUT1
16
GPIO0
13
12
11
14
15
GPIO3
GPIO2
GPIO1
OT
PRESET0
4
3
2
1
PRESET4
GPIO4
SMBCLK
SMBDATA
5 DXP1
6 7 8 9
DXN
DXP2 GND
PRESET2
10
PRESET1
MAX6678
*CONNECT EXPOSED
PADDLE TO GND
TOP VIEW
5mm x 5mm THIN QFN
Pin Configurations
Ordering Information
19-3306; Rev 0; 5/04
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.
*EP = Exposed paddle.
PART TEMP RANGE
PIN-
PACKAGE SMBus
ADDRESS
MAX6678AEP90 -40°C to +125°C 20 QSOP 1001000
MAX6678AEP92 -40°C to +125°C 20 QSOP 1001001
MAX6678AEP94 -40°C to +125°C 20 QSOP 1001010
MAX6678AEP96 -40°C to +125°C 20 QSOP 1001011
MAX6678ATP90 -40°C to +125°C
20 Thin
QFN-EP*
1001000
MAX6678ATP92 -40°C to +125°C
20 Thin
QFN-EP*
1001001
MAX6678ATP94 -40°C to +125°C
20 Thin
QFN-EP*
1001010
MAX6678ATP96 -40°C to +125°C
20 Thin
QFN-EP*
1001011
SMBus is a trademark of Intel Corp.
Pin Configurations continued at end of data sheet.
Typical Operating Circuit appears at end of data sheet.