MAX6660 Datasheet, PDF (1/21 Pages) Maxim Integrated Products – Remote-Junction Temperature-Controlled Fan-Speed Regulator with SMBus Interface

19-2225; Rev 0; 10/01
Remote-Junction Temperature-Controlled
Fan-Speed Regulator with SMBus Interface
General Description
The MAX6660 is a remote temperature sensor and fan-
speed regulator that provides a complete fan-control
solution. The remote temperature sensor is typically a
common-collector PNP, such as a substrate PNP of a
microprocessor, or a diode-connected transistor, typi-
cally a low-cost, easily mounted 2N3904 NPN type or
2N3906 PNP type.
The device also incorporates a closed-loop fan con-
troller that regulates fan speed with tachometer feed-
back. The MAX6660 compares temperature data to a
fan threshold temperature and gain setting, both pro-
grammed over the SMBus™ by the user. The result is
automatic fan control that is proportional to the remote-
junction temperature. The temperature feedback loop
can be broken at any time for system control over the
speed of the fan.
Fan speed is voltage controlled as opposed to PWM
controlled, greatly reducing acoustic noise and maxi-
mizing fan reliability. An on-chip power device drives
fans rated up to 250mA.
Temperature data is updated every 0.25s and is read-
able at any time over the SMBus interface. The
MAX6660 is accurate to 1°C (max) when the remote
junction is between +60°C to +100°C. Data is formatted
as a 10-bit + sign word with 0.125°C resolution.
The MAX6660 is specified for -40°C to +125°C and is
available in a 16-pin QSOP package.
Applications
PC
Notebooks
Telecom Systems
Industrial Control Systems
Servers
Workstations
SMBus is a trademark of Intel Corp.
Pin Configuration appears at end of data sheet.
Features
♦ Integrated Thermal Sensing and Fan-Regulation
Solution
♦ Programmable Fan Threshold Temperature
♦ Programmable Temperature Range for Full-Scale
Fan Speed
♦ Accurate Closed-Loop Fan-Speed Regulation
♦ On-Chip Power Device Drives Fans Rated
Up to 250mA
♦ Programmable Under/Overtemperature Alarms
♦ SMBus 2-Wire Serial Interface with Timeout
(Cannot “Lock Up” the SMBus)
♦ Supports SMBus Alert Response
♦ ACPI Compatible, Including OVERT System
Shutdown Function
♦ ±1°C (+60°C to +100°C) Thermal-Sensing Accuracy
♦ MAX6660EVKIT Available
Ordering Information
PART
MAX6660AEE
TEMP. RANGE
-40°C to +125°C
PIN-PACKAGE
16 QSOP
Typical Operating Circuit
0.1µF
+12V
+3V TO +5.5V
50Ω
10kΩ
EACH
5kΩ
VFAN VCC STBY
1µF
FAN
TACH IN
SMBCLK
FAN ^MAX6660
SMBDATA
DXP
2200pF
ALERT
PENTIUM
DXN
AGND
OVERT
ADD0 ADD1 PGND
CLOCK
DATA
INTERUPT
TO µP
TO SYSTEM
SHUTDOWN
________________________________________________________________ Maxim Integrated Products 1
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