参数资料
| 型号： | ADT7468ZEVB |
| 厂商： | ON Semiconductor |
| 文件页数： | 56/81页 |
| 文件大小： | 0K |
| 描述： | BOARD EVAL FOR ADT7468 |
| 标准包装： | 1 |
| 其它名称： | EVAL-ADT7468EB EVAL-ADT7468EB-ND |
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ADT7468
Preventing T MIN from Reaching Full Scale
Because T MIN is dynamically adjusted, it is undesirable for T MIN
to reach full scale (127°C), because the fan would never switch
on. As a result, T MIN is allowed to vary only within a specified
range:
The operating point contains the temperature at which THERM
is asserted. This allows the system to run as quietly as possible
without affecting system performance.
PHTR2 = 0, ignores any THERM assertions. The Remote 2
operating point register reflects its programmed value.
1.
2.
3.
The lowest possible value for T MIN is –127°C (twos
complement mode) or ?64°C (Offset 64 mode).
T MIN cannot exceed the high temperature limit.
If the temperature is below T MIN , the fan is switched off or
is running at minimum speed, and dynamic T MIN control is
disabled.
THERM
LIMIT
<3> PHTL = 1, copies the local current temperature to the local
temperature operating point register, if THERM is asserted. The
operating point contains the temperature at which THERM is
asserted. This allows the system to run as quietly as possible
without affecting system performance.
PHTL = 0, ignores any THERM assertions. The local
temperature operating point register reflects its programmed
OPERATING
POINT
LOW TEMP
LIMIT
HIGH TEMP
LIMIT
T MIN
HYSTERESIS
ACTUAL
TEMP
T MIN PREVENTED
FROM INCREASING
value.
<4> PHTR1 = 1, copies the Remote 1 current temperature to
the Remote 1 operating point register, if THERM is asserted.
The operating point contains the temperature at which THERM
is asserted. This allows the system to run as quietly as possible
without affecting system performance.
PHTR1 = 0, ignores any THERM assertions. The Remote 1
Figure 76. T MIN Adjustments Limited by the High Temperature Limit
STEP 11: MONITORING THERM
Using the operating point limit ensures that the dynamic T MIN
control mode is operating in the best possible acoustic position
while ensuring that the temperature never exceeds the
maximum operating temperature. Using the operating point
limit allows T MIN to be independent of system level issues
because of its self-corrective nature. In PC design, the
operating point for the chassis is usually the worst-case
internal chassis temperature.
The optimal operating point for the processor is determined by
monitoring the thermal monitor in the Intel Pentium 4 proces-
sor. To do this, the PROCHOT output of the Pentium 4 is
connected to the THERM input of the ADT7468.
The operating point for the processor can be determined by
allowing the current temperature to be copied to the operating
point register when the PROCHOT output pulls the THERM
input low on the ADT7468. This gives the maximum
temperature at which the Pentium 4 can run before clock
modulation occurs.
Enabling the THERM Trip Point as the Operating Point
Bits <4:2> of dynamic T MIN control Register 1 (Reg. 0x36)
enable/disable THERM monitoring to program the operating
point.
Dynamic T MIN Control Register 1 (0x36)
<2> PHTR2 = 1, copies the Remote 2 current temperature to
operating point register reflects its programmed value.
Enabling Dynamic T MIN Control Mode
Bits <7:5> of dynamic T MIN control Register 1 (Reg. 0x36)
enable/disable dynamic T MIN control on the temperature
channels.
Dynamic TMIN Control Register 1 (0x36)
<5> R2T = 1, enables dynamic T MIN control on the Remote 2
temperature channel. The chosen T MIN value is dynamically
adjusted based on the current temperature, operating point, and
high and low limits for this zone.
R2T = 0, disables dynamic T MIN control. The T MIN value chosen
is not adjusted and the channel behaves as described in the
Automatic Fan Control Overview section.
<6> LT = 1, enables dynamic T MIN control on the local temp-
erature channel. The chosen T MIN value is dynamically adjusted
based on the current temperature, operating point, and high
and low limits for this zone.
LT = 0, disables dynamic T MIN control. The T MIN value chosen is
not adjusted and the channel behaves as described in the
Automatic Fan Control Overview section.
<7> R1T = 1, enables dynamic T MIN control on the Remote 1
temperature channel. The chosen T MIN value is dynamically
adjusted based on the current temperature, operating point, and
high and low limits for this zone.
R1T = 0, disables dynamic T MIN control. The T MIN value chosen
is not adjusted and the channel behaves as described in the
Automatic Fan Control Overview section.
the Remote 2 operating point register, if THERM is asserted.
Rev. 3 | Page 56 of 81 | www.onsemi.com
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相关代理商/技术参数 |
参数描述 |
|---|---|
| ADT7470 | 制造商:AD 制造商全称:Analog Devices 功能描述:Temperature Sensor Hub and Fan Controller |
| ADT7470_13 | 制造商:AD 制造商全称:Analog Devices 功能描述:Temperature Sensor Hub and Fan Controller |
| ADT7470ARQ | 制造商:Analog Devices 功能描述:Temp Sensor Digital Serial (I2C) 16-Pin QSOP |
| ADT7470ARQ-REEL | 制造商:Rochester Electronics LLC 功能描述: 制造商:Analog Devices 功能描述: |
| ADT7470ARQ-REEL7 | 制造商:Analog Devices 功能描述:Temp Sensor Digital Serial (I2C) 16-Pin QSOP T/R |
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