ADT7460ARQZ-RL7 ONSEMI [ON Semiconductor], ADT7460ARQZ-RL7 Datasheet - Page 8

• Manufacturer Part Number: ADT7460ARQZ-RL7
• Description: dBCOOL Remote Thermal Monitor and Fan Controller
• Manufacturer: ONSEMI [ON Semiconductor]

Product Description
controller for any system requiring monitoring and cooling.
The device communicates with the system via a serial
System Management Bus (SMBus). The serial bus
controller has an optional address line for device selection
(Pin 9), a serial data line for reading and writing addresses
and data (Pin 16), and an input line for the serial clock
(Pin 1). All control and programming functions of the
ADT7460 are performed over the serial bus. In addition, two
of the pins can be reconfigured as an SMBALERT output to
indicate out−of−limit conditions.
Measurement Inputs
and two for temperature. It can also measure its own supply
voltage and can measure ambient temperature with its
on−chip temperature sensor.
is configured to monitor 2.5 V.
monitors V
connected to a 3.3 V standby supply. This pin can, however,
be connected to a 5.0 V supply and monitor it without
over−ranging.
D2±
temperature−sensing transistors, such as a 2N3904 or CPU
thermal diode, may be connected.
The ADT7460 is a thermal monitor and multiple fan
The device has three measurement inputs, one for voltage
Pin 14 is an analog input with an on−chip attenuator and
Power is supplied to the chip via Pin 3, and the system also
Remote temperature sensing is provided by the D1± and
inputs,
CC
through this pin. In PCs, this pin is normally
to
which
FRONT
CHASSIS
FAN
REAR
CHASSIS
FAN
AMBIENT
TEMPERATURE
diode−connected,
Figure 12. Recommended Implementation
external
http://onsemi.com
TACH2
PWM3
TACH3
D1+
D1–
ADT7460
ADT7460
GND
8
SMBALERT
temperature sensor, which monitors system ambient
temperature.
Sequential Measurement
cycles sequentially through the measurement of 2.5 V input
and the temperature sensors. Measured values from these
inputs are stored in value registers. These 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.
Recommended Implementation
systems designer the following features:
THERM
TACH1
PWM1
The ADC also accepts input from an on−chip band gap
When the ADT7460 monitoring sequence is started, it
Configuring the ADT7460 as in Figure 12 allows the
♦
♦
♦
♦
♦
♦
♦
SDA
SCL
D2+
D2–
fans (the front and rear chassis fans are connected in
parallel).
temperature channel.
temperature channel.
PROCHOT monitoring and can function as an
overtemperature THERM output.
Two PWM outputs for fan control of up to three
Three TACH fan speed measurement inputs.
V
CPU temperature measured using Remote 1
Ambient temperature measured through Remote 2
Bidirectional THERM pin. Allows Intel Pentium 4
SMBALERT system interrupt output.
CC
PROCHOT
measured internally through Pin 3.
CPU FAN
ICH
CPU