dBCool
™
Remote Thermal
Controller and Voltage Monitor

ADT7468


Rev. 0
Information furnished by Analog Devices is believed to be accurate and reliable.
However, no responsibility is assumed by Analog Devices for its use, nor for any
infringements of patents or other rights of third parties that may result from its use.
Specifications subject to change without notice. No license is granted by implication
or otherwise under any patent or patent rights of Analog Devices. Trademarks and
registered trademarks are the property of their respective owners.

One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700 www.analog.com
Fax: 781.326.8703 © 2004 Analog Devices, Inc. All rights reserved.
FEATURES
Monitors up to 5 voltages
Controls and monitors up to 4 fans
High and low frequency fan drive signal
1 on-chip and 2 remote temperature sensors
Series resistance cancellation on the remote channel
Extended temperature measurement range, up to 191°C
Dynamic TMIN control mode optimizes system acoustics
intelligently
Automatic fan speed control mode controls system
cooling based on measured temperature
Enhanced acoustic mode dramatically reduces user
perception of changing fan speeds
Thermal protection feature via THERM output
Monitors performance impact of Intel® Pentium™ 4
processor
Thermal control circuit via THERM input
2-wire, 3-wire, and 4-wire fan speed measurement
Limit comparison of all monitored values
Meets SMBus 2.0 electrical specifications
(fully SMBus 1.1 compliant)
GENERAL DESCRIPTION
The ADT7468 dBCOOL
TM
controller is a thermal monitor and
multiple PWM fan controller for noise-sensitive or power-
sensitive applications requiring active system cooling. The
ADT7468 can drive a fan using either a low or high frequency
drive signal, monitor the temperature of up to two remote
sensor diodes plus its own internal temperature, and measure
and control the speed of up to four fans, so that they operate at
the lowest possible speed for minimum acoustic noise.
The automatic fan speed control loop optimizes fan speed for a
given temperature. A unique dynamic TMIN control mode
enables the system thermals/acoustics to be intelligently
managed. The effectiveness of the system’s thermal solution can
be monitored using the THERM input. The ADT7468 also
provides critical thermal protection to the system using the
bidirectional THERM pin as an output to prevent system or
component overheating.
FUNCTIONAL BLOCK DIAGRAM
04499-0-001
INPUT
SIGNAL
CONDITIONING
AND
ANALOG
MULTIPLEXER
GND
SERIAL BUS
INTERFACE
SCL SDA
VALUE AND
LIMIT
REGISTERS
LIMIT
COMPARATORS
INTERRUPT
STATUS
REGISTERS
BAND GAP
TEMP SENSOR
V
CC
TO ADT7468
ADDRESS
POINTER
REGISTER
PWM
CONFIGURATION
REGISTERS
INTERRUPT
MASKING
V
CC
D1+
D1–
D2+
D2–
+5V
IN
THERMAL
PROTECTION
PERFORMANCE
MONITORING
PWM REGISTERS
AND
CONTROLLERS
HF & LF
PWM1
PWM2
PWM3
ACOUSTIC
ENHANCEMENT
CONTROL
BAND GAP
REFERENCE
10-BIT
ADC
ADT7468
AUTOMATIC
FAN SPEED
CONTROL
DYNAMIC
T
MIN
CONTROL
FAN SPEED
COUNTER
TACH1
TACH2
TACH3
TACH4
ACOUSTIC
ENHANCEMENT
CONTROL
SRC
+12V
IN
+2.5V
IN
V
CCP
VID5
VID4
VID3
VID2
VID1
VID0
THERM
SMBALERT

Figure 1.