ADT7467ARQZ-R71 データシートの表示（PDF） - ON Semiconductor
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ADT7467ARQZ-R71 Datasheet PDF : 77 Pages
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ADT7467
Configuration Register 5
Bit 0: If Bit 0 is set to 1, the ADT7467, in terms of temperature,
is backward compatible with the ADT7460. Measurements,
including TMIN calibration circuit and fan control, work in the
range −127°C to +127°C. In addition, care should be taken in
reprogramming the temperature limits (TMIN, operating point,
THERM) to their desired twos complement value, because the
power-on default for them is at Offset 64. The extended
temperature range is −64°C to 191°C. The default is 1, which is
in the −64°C to +191°C temperature range.
Bit 1 = 0 is the high frequency (22.5 kHz) fan drive signal.
Bit 1 = 1 switches the fan drive to low frequency PWM,
programmable between 10 Hz and 100 Hz, the same as the
ADT7460. The default is 0, or HF PWM.
Bit 2 sets the direction for the GPIO: 0 = input, 1 = output.
Bit 3 sets the GPIO polarity: 0 = active low, 1 = active high.
Setting the Functionality of Pin 9
Pin 9 on the ADT7467 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
at Address 0x7D.
Table 4. Pin 9 Settings
Bit 1
Bit 0
Function
0
0
TACH4
0
1
THERM
1
0
SMBALERT
1
1
GPIO
RECOMMENDED IMPLEMENTATION
Configuring the ADT7467 as in Figure 15 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 the Remote 1
temperature channel.
• Ambient temperature measured through the Remote 2
temperature channel.
• Bidirectional THERM pin. This feature allows Intel
Pentium 4 PROCHOT monitoring and can function as an
overtemperature THERM output. Alternatively, it can be
programmed as an SMBALERT system interrupt output.
FRONT
CHASSIS
FAN
REAR
CHASSIS
FAN
AMBIENT
TEMPERATURE
ADT7467
TACH2
PWM1
TACH1
CPU FAN
PWM3
TACH3
D1+
D1–
D2+
D2–
THERM
PROCHOT
CPU
SDA
SCL
SMBALERT
GND
ICH
Figure 15. ADT7467 Configuration
Rev. 3 | Page 10 of 77 | www.onsemi.com
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