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PDF ADT7466 Data sheet ( Hoja de datos )
| Número de pieza | ADT7466 | |
| Descripción | dBCool Remote Thermal Controller and Voltage Monitor | |
| Fabricantes | Analog Devices | |
| Logotipo |  |
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dBCool® Remote Thermal
Controller and Voltage Monitor
ADT7466
FEATURES
Monitors two analog voltages or thermistor temperature
inputs
One on-chip and up to two remote temperature sensors with
series resistance cancellation
Controls and monitors the speed of up to two fans
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 PROCHOT input
3-wire fan speed measurement
Limit comparison of all monitored values
SMBus 1.1 serial interface
GENERAL DESCRIPTION
The ADT7466 dBCool controller is a complete thermal monitor
and dual fan controller for noise-sensitive applications
requiring active system cooling. It can monitor two analog
voltages or the temperature of two thermistors, plus its own
supply voltage. It can monitor the temperature of up to two
remote sensor diodes, plus its own internal temperature. It can
measure and control the speed of up to two 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. The effectiveness of the system’s
thermal solution can be monitored using the PROCHOT input
to time and monitor the PROCHOT output of the processor.
APPLICATIONS
Low acoustic noise notebook PCs
FUNCTIONAL BLOCK DIAGRAM
VCC
SCL SDA ALERT
DRIVE1
DRIVE2
TACH1
TACH2
FANLOCK
FAN1_ON/
PROCHOT/
THERM
8-BIT
DAC
8-BIT
DAC
FAN1
ENABLE
D1+
D1–
AIN1/TH1/D2–
AIN2/TH2/D2+
SERIES
RESISTANCE
CANCELLATION
SERIES
RESISTANCE
CANCELLATION
BAND GAP
TEMPERATURE
SENSOR
V_FAN_MIN
V_FAN_ON
CONTROL
ACOUSTIC
ENHANCEMENT
CONTROL
FAN
SPEED
MONITOR
AUTOMATIC
FAN SPEED
CONTROL
PROCHOT
INPUT
SIGNAL
CONDITIONING
AND
ANALOG
MULTIPLEXER
10-BIT
ADC
BAND GAP
REFERENCE
SERIAL BUS
INTERFACE
ADDRESS
POINTER
REGISTER
CONFIGURATION
REGISTERS
THERM
REGISTER
INTERRUPT
MASKING
INTERRUPT
STATUS
REGISTERS
LIMIT
COMPARATORS
VALUE AND
LIMIT
REGISTERS
ADT7466
GND
Figure 1.
Protected by U.S. Patent Numbers 6,188,189; 6,169,442; 6,097,239; 5,982,221; 5,867,012.
REFOUT
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: 781.461.3113 © 2005 Analog Devices, Inc. All rights reserved.
1 page  
SERIAL BUS TIMING
SCL
SDA
tBUF
PS
tR
tLOW
t HD; STA
tHD;DAT
tF
tHIGH
tSU;DAT
tHD;STA
tSU;STA
S
Figure 2. Diagram for Serial Bus Timing
tSU;STO
P
ADT7466
Rev. 0 | Page 5 of 48
5 Page 
ADT7466
FUNCTIONAL DESCRIPTION
The ADT7466 is a complete thermal monitor and dual fan
controller for any system requiring monitoring and cooling.
The device communicates with the system via a serial system
management bus (SMBus). The serial data line (SDA, Pin 15) is
used for reading and writing addresses and data. The input line,
(SCL, Pin 16) is the serial clock. All control and programming
functions of the ADT7466 are performed over the serial bus. In
addition, an ALERT output is provided to indicate out-of-limit
conditions.
MEASUREMENT INPUTS
The device has three measurement inputs, two for voltage and
one for temperature. It can also measure its own supply voltage
and can measure ambient temperature with its on-chip
temperature sensor.
Pin 11 and Pin 12 are analog inputs with an input range of 0 V
to 2.25 V. They can easily be scaled for other input ranges by
using external attenuators. These pins can also be configured
for temperature monitoring by using thermistors or a second
remote diode temperature measurement.
The ADT7466 can simultaneously monitor the local
temperature, the remote temperature by using a discrete
transistor, and two thermistor temperatures.
Remote temperature sensing is provided by the D+ and D−
inputs, to which diode connected, remote temperature sensing
transistors such as a 2N3904 or CPU thermal diode can be
connected.
Temperature sensing using thermistors is carried out by placing
the thermistor in series with a resistor. The excitation voltage is
provided by the REFOUT pin.
The device also accepts input from an on-chip band gap
temperature sensor that monitors system ambient temperature.
Power is supplied to the chip via Pin 6. The system also
monitors VCC through this pin. It is normally connected to a
3.3 V supply. It can, however, be connected to a 5 V supply and
monitored without going over range.
SEQUENTIAL MEASUREMENT
When the ADT7466 monitoring sequence is started, it
sequentially cycles through the measurement of analog inputs
and the temperature sensors. Measured values from these
inputs are stored in value registers, which can be read out over
the serial bus, or can be compared with programmed limits
stored in the limit registers. The results of out of limit
comparisons are stored in the status registers, which can be read
over the serial bus to flag out-of-limit conditions.
FAN SPEED MEASUREMENT AND CONTROL
The ADT7466 has two tachometer inputs for measuring the
speed of 3-wire fans, and it has two 8-bit DACs to control the
speed of two fans. The temperature measurement and fan speed
control can be linked in an automatic control loop, which can
operate without CPU intervention to maintain system operating
temperature within acceptable limits. The enhanced acoustics
feature ensures that fans operate at the minimum possible speed
consistent with temperature control, and change speed
gradually. This reduces the user’s perception of changing fan
speed.
INTERNAL REGISTERS OF THE ADT7466
Table 4 provides brief descriptions of the ADT7466’s principal
internal registers. More detailed information on the function of
each register is given in Table 30 to Table 72.
Table 4. Internal Register Summary
Register
Description
Configuration
These registers provide control and configuration of the ADT7466 including alternate pinout functionality.
Address Pointer
This register contains the address that selects one of the other internal registers. When writing to the ADT7466, the
first byte of data is always a register address, which is written to the address pointer register.
Status
These registers provide status of each limit comparison and are used to signal out-of-limit conditions on the
temperature, voltage, or fan speed channels. Whenever a status bit is set, the ALERT output (Pin 14) goes low.
Interrupt Mask
These registers allow interrupt sources to be masked so that they do not affect the ALERT output.
Value and Limit
The results of analog voltage inputs, temperature, and fan speed measurements are stored in these registers, along
with their limit values.
Offset
These registers allow each temperature channel reading to be offset by a twos complement value written to these
registers.
PROCHOT Status
This register allows the ADT7466 to monitor and time any PROCHOT events gauging system performance.
TMIN
TRANGE
These registers program the starting temperature for each fan under automatic fan speed control.
These registers program the temperature-to-fan speed control slope in automatic fan speed control mode for each
fan drive output.
Enhance Acoustics This register sets the step size for fan drive changes in AFC mode to minimize acoustic noise.
Rev. 0 | Page 11 of 48
11 Page | ||
| Páginas | Total 30 Páginas | |
| PDF Descargar | [ Datasheet ADT7466.PDF ] | |
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