ADT7473ARQZ-RL7 View Datasheet(PDF) - ON Semiconductor
Part Name
Description
Manufacturer
ADT7473ARQZ-RL7 Datasheet PDF : 74 Pages
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ADT7473
Product Description
The ADT7473/ADT7473−1 is a complete thermal
monitor and multiple fan controller for any system requiring
thermal monitoring and cooling. The device communicates
with the system via a serial system management bus. The
serial bus controller has 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
for the ADT7473/ADT7473−1 are performed over the serial
bus. Additionally, a pin can be reconfigured as an
SMBALERT output to signal out−of−limit conditions.
Table 1 illustrates the differences between the ADT7473
and the ADT7473−1.
Table 1. ADT7473/ADT7473−1 Device Comparison
Feature
Pin 5
SMBus Address
Remote Ch. 2
Therm Limit
Register 0x30,
0x31, 0x32
ADT7473
Default:
PWM2
Fixed
Address
= 100°C
ADT7473−1
Default:
THERM_LATCH
Address selectable
= 136°C
Default:
0x00
Default: 0xFF
Register 0x3F
Revision Reg
Default:
0x68
Default: 0x69
Register 0x40, Bit 7 Reserved
(R/W) 1 = Reset Latch
(lockable)
Register 0x42, Bit 0 Reserved
Registers 0x5C,
0x5D, 0x5E
Register 0x7C, Bit 4
Default:
0x82
Reserved
Register 0x7D, Bit 4 Reserved
(Read−only)
1 = THERM
Limit Latched
Default: 0x62
THERM Output
Hysteresis
THERM_LATCH
Configuration
0 = Remote Channel 2
1 = Remote Channel 1
and Remote Channel 2
Comparison Between ADT7467 and
ADT7473/ADT7473−1
The following list shows some comparisons between the
ADT7467 and the ADT7473/ADT7473−1:
• The ADT7473/ADT7473−1 can be powered via a
3.3 V supply only, and does not support 5.0 V
operation, while the ADT7467 does. Violating this
specification results in irreversible damage to the
ADT7473/ADT7473−1. See the Specifications section
for more information.
• A high frequency PWM drive can be independently
selected for each PWM channel on the
ADT7473/ADT7473−1. This is not available on the
ADT7467.
• The range and resolution of the temperature offset
register can be changed from a ±64°C range at 0.5°C
resolution to a ±128°C range at 1°C resolution. This is
not available on the ADT7467.
• THERM overtemperature events can be
disabled/enabled individually on each temperature
channel. This is not available on the ADT7467.
• Bit 7 of Configuration Register 1 is no longer supported
because the ADT7473/ADT7473−1 cannot be powered
via a 5.0 V supply.
• Bit 0 of Configuration Register 1 (0x40) remains
writable after the lock bit is set. This bit enables
monitoring.
• 2−wire fan speed measurement is not supported on the
ADT7473/ADT7473−1.
How to Set the Functionality of Pin 9
Pin 9 on the ADT7473/ADT7473−1 has four possible
functions: SMBALERT, THERM, GPIO, and TACH4. The
user chooses the required functionality by setting Bit 0 and
Bit 1 of Configuration Register 4 (0x7D).
Table 2. Pin 9 Settings
Bit 0
0
0
1
1
Bit 1
0
1
0
1
TACH4
THERM
SMBALERT
GPIO
Function
Recommended Implementation
Configuring the ADT7473 as shown in Figure 12 allows
the system designer to use the following features:
• Two PWM outputs for fan control of up to three fans.
(The front and rear chassis fans are connected in
parallel.)
• Three TACH fan speed measurement inputs.
• VCC measured internally through Pin 3.
• CPU temperature measured using Remote 1
temperature channel.
• Ambient temperature measured through Remote 2
temperature channel.
• Bidirectional THERM pin. This feature allows Intel
Pentium 4 PROCHOT monitoring and can function as
an overtemperature THERM output. It can alternatively
be programmed as an SMBALERT system interrupt
output.
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