Burr Brown Products
from Texas Instruments
AM
C68
21
SBAS386C – MAY 2006 – REVISED JULY 2007
Intelligent Temperature Monitor and PWM Fan Controller
1
FEATURES
DESCRIPTION
The AMC6821 is an intelligent temperature monitor
and pulse-width modulation (PWM) fan controller. It is
designed for noise-sensitive or power-sensitive
applications that require active system cooling. Using
either a low-frequency or a high-frequency PWM
signal, this device can simultaneously drive a fan,
monitor remote sensor diode temperatures, and
measure and control the fan speed so that it operates
with minimal acoustic noise at the lowest possible
speed.
The AMC6821 has three fan control modes: Auto
Temperature-Fan mode, Software-RPM mode, and
Software-DCY mode. Each mode controls the fan
speed by changing the duty cycle of a PWM output.
Auto Temperature-Fan mode is an intelligent,
closed-loop control that optimizes fan speed
according to user-defined parameters. This mode
allows the AMC6821 to run as a stand-alone device
without CPU intervention; the fan can continue to be
controlled (based on temperature measurements)
even if the CPU or system locks up. Software-RPM
mode is a second closed-loop control. In this mode,
the AMC6821 adjusts the PWM output to maintain a
consistent fan speed at a user-specified target value;
that is, the device functions as a fan speed regulator.
Software-RPM mode can also be used to allow the
AMC6821 to operate as a stand-alone device. The
third mode, Software-DCY, is open-loop. In
Software-DCY mode, the PWM duty cycle is set
directly by the value written to the device.
The AMC6821 has a programmable SMBALERT
output to indicate error conditions and a dedicated
FAN-FAULT output to indicate fan failure. The
THERM pin is a fail-safe output for over-temperature
conditions that can be used to throttle a CPU clock.
Additionally,
the
OVR
pin
indicates
the
over-temperature limit as well. All of the alarm
thresholds are set through the device registers. The
AMC6821 is available in a QSOP-16 package.
•
Remote Temperature Sensor:
±2°C Accuracy, 0.125°C Resolution
•
Local Temperature Sensor:
±2°C Accuracy, 0.125°C Resolution
•
PWM Controller
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PWM Frequency: 10Hz to 40kHz
Duty Cycle: 0% to 100%, 8 Bits
•
Automatic Fan Speed Control Loops
•
SMBus Interface
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Power: 2.7V to 5.5V
•
Package (Green): QSOP-16 (4mm
×
5mm)
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RoHS Compliant
23456
APPLICATIONS
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•
•
•
•
Notebook and Desktop PCs
Network Servers
Telecommunications Equipment
PC-Based Equipment
DLP™ and LCD Projectors
V
DD
GND
AMC6821
FAN-FAULT
THERM
OVR
Alarm
Detectors
SMBus
2
IC
Interface
SMBALERT
SDA
SCLK
A1
A0
Temperature
Data
IN+
MUX
ADC
(11-Bit)
TACH-DATA
TACH COUNTER
TACH
IN-
PWM-Out
On-Chip
Temperature Sensor
Ref
Remote
Temperature
Sensing
PWM
Driver
PWM-MODE
Auto Fan Speed
Controller
Patents 7, 083,328 and 7,098,617.
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Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of
Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
DLP is a trademark of Texas Instruments.
Pentium M, Pentium-IV are trademarks of Intel.
JMC is a trademark of JMC Products.
I2C is a trademark of Philips International, Inc.
All other trademarks are the property of their respective owners.
Copyright © 2006–2007, Texas Instruments Incorporated
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
TI [ TEXAS INSTRUMENTS ]
