ADT7467ARQZ-REEL データシートの表示（PDF） - ON Semiconductor
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ADT7467ARQZ-REEL Datasheet PDF : 72 Pages
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ADT7467
Product Description
The ADT7467 is a complete thermal monitor and multiple
fan controller for systems 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 ADT7467 are
performed over the serial bus. In addition, one of two pins
can be reconfigured as an SMBALERT output to signal
out-of-limit conditions.
Comparison between ADT7460 and ADT7467
The ADT7467 is an upgrade from the ADT7460. The
ADT7467 and ADT7460 are almost pin and register map
compatible. The ADT7467 and ADT7460 have the
following differences:
1. On the ADT7467, the PWM drive signals can be
configured as either high frequency or low
frequency drives. The low frequency option is
programmable between 10 Hz and 100 Hz. The
high frequency option is 22.5 kHz. On the
ADT7460, only the low frequency option is
available.
2. Once VCC and VCCP are powered up, monitoring
of temperature and fan speeds is enabled on the
ADT7467. If VCCP is never powered up,
monitoring is enabled when the first SMBus
transaction with the ADT7467 is complete. On the
ADT7460, the STRT bit in Configuration Register
1 must be set to enable monitoring.
3. The fans are switched off by default upon
power-up of the ADT7467. On the ADT7460, the
fans run at full speed upon power-up.
Fail-safe cooling is provided on the ADT7467. If
the measured temperature exceeds the THERM
limit (100C), the fans run at full speed.
Fail-safe cooling is also provided 4.6 sec after
VCCP is powered up. The fans operate at full speed
if the ADT7467 has not been addressed via the
SMBus within 4.6 sec of when the VCCP is
powered up. This protects the system in the event
that the SMBus fails. The ADT7467 can be
programmed at any time, and it behaves as
programmed. If VCCP is never powered up,
fail-safe cooling is effectively disabled. If VCCP is
disabled, writing to the ADT7467 at any time
causes the ADT7467 to operate normally.
4. Series resistance cancellation (SRC) is provided
on the remote temperature channels on the
ADT7467, but not on the ADT7460. SRC
automatically cancels linear offset introduced by a
series resistance between the thermal diode and the
sensor.
5. The ADT7467 has an extended temperature
measurement range. The measurement range goes
from −64C to +191C. On the ADT7460, the
measurement range is from −127C to +127C.
This means that the ADT7467 can measure higher
temperatures. The ADT7467 also includes the
ADT7460 temperature range; the temperature
measurement range can be switched by setting
Bit 0 of Configuration Register 5.
6. The ADT7467 maximum fan speed (% duty cycle)
in the automatic fan speed control loop can be
programmed. The maximum fan speed is 100%
duty cycle on the ADT7460 and is not
programmable.
7. The offset register in the ADT7467 is
programmable up to 64C with 0.50C
resolution. The offset register of the ADT7460 is
programmable up to 32C with 0.25C
resolution.
8. VCCP is monitored on Pin 14 of the ADT7467 and
can be used to set the threshold for THERM
(PROCHOT) (2/3 of VCCP). 2.5 V is monitored on
Pin 14 of the ADT7460. The threshold for
THERM (PROCHOT) is set at VIH = 1.7 V and
VIL = 0.8 V on the ADT7460.
9. On the ADT7460, Pin 14 could be reconfigured as
SMBALERT. This is not available on the ADT7467.
SMBALERT can be enabled instead on Pin 9.
10. A GPIO can also be made available on Pin 9 on the
ADT7467. This is not available on the ADT7460.
Set the GPIO polarity and direction in Configuration
Register 5. The GPIO status bit is Bit 5 of Status
Register 2 (it is shared with TACH4 and THERM
because only one can be enabled at a time).
11. The ADT7460 has three possible SMBus
addresses, which are selectable using the address
select and address enable pins. The ADT7467 has
one SMBus address available at Address 0x2E.
Due to the inclusion of extra functionality, the register
map has changed, including an additional configuration
register, Configuration Register 5 at Address 0x7C.
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 −127C to +127C. 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 −64C to
191C. The default is 1, which is in the −64C to +191C
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.
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