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參數(shù)資料
| 型號： | ASC7512D8 |
| 廠商： | Electronic Theatre Controls, Inc. |
| 元件分類： | 溫度/濕度傳感器 |
| 英文描述： | DIGITAL TEMPERATURE SENSOR WITH INTEGRATED FAN CONTROL |
| 中文描述： | 數(shù)字溫度傳感器整合了風(fēng)扇控制 |
| 文件頁數(shù)： | 30/35頁 |
| 文件大?。?/td> | 337K |
| 代理商： | ASC7512D8 |
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Andigilog, Inc. 2006
www.andigilog.com
August 2006 - 70A05003
aSC7512
Applications Information
Remote Diodes
The aSC7512 is designed to work with a variety of
remote sensors in the form of the substrate thermal diode
of a CPU or graphics controller or a diode-connected
transistor. Actual diodes are not suited for these
measurements.
There is some variation in the performance of these
diodes, described in terms of its departure from the ideal
diode equation. This factor is called diode non-
ideality,
.
nf
The equation relating diode temperature to a change in
thermal diode voltage with two driving currents is:
Δ
V
BE
=
(nf )KT
q
ln(N)
where:
nf
= diode non-ideality factor, (nominal 1.008).
K
= Boltzman’s constant, (1.38 x 10
-23
).
T
= diode junction temperature in Kelvins.
q
= electron charge (1.6 x 10
Coulombs).
N
= ratio of the two driving currents (16).
The aSC7512 is designed and trimmed for an expected
nf
value of 1.008, based on the typical value for the Intel
Pentium III and AMD Athlon. There is also a
tolerance on the value provided. The values for other
CPUs and the 2N3904 may have different nominal values
and tolerances. Consult the CPU or GPU manufacturer’s
data sheet for the
nf
factor. Table 23 gives a
representative sample of what one may expect in the
range of non-ideality. The trend with CPUs is for a lower
value with a larger spread.
When thermal diode has a non-ideality factor other than
1.008 the difference in temperature reading at a particular
temperature may be interpreted with the following
equation:
=
actual
n
reported
T
actual
T
008
.
where:
T
reported
T
n
Temperatures are in Kelvins or °C + 273.15.
= reported temperature in temperature register.
actual
= actual remote diode temperature.
= selected diode’s non-ideality factor,
nf
.
actual
This equation assumes that the series resistance of the
remote diode is the same for each. This resistance is
given in the data sheet for the CPU and may vary from
2.5
to 4.5
.
Although the temperature error caused by non-ideality
difference is directly proportional to the difference from
1.008, but a small difference in non-ideality results in a
relatively large difference in temperature reading. For
example, if there were a ±1% tolerance in the non-Ideality
of a diode it would result in a ±2.7 degree difference (at
0°C) in the result (0.01 x 273.15).
This difference varies with temperature such that a fixed
offset value may only be used over a very narrow range.
Typical correction method required when measuring a
wide range of temperature values is to scale the
temperature reading in the host firmware.
Part
nf
Min
nf
Nom
nf
Max
Series
Res
Pentium III
(CPUID 68h)
Pentium 4,
130nM
Pentium 4, 90nM
Intel Pentium M
AMD Athlon
Model 6
AMD Duron
Models 7 and 8
AMD Athlon
Models 8 and 10
2N3904
1.0057
1.008
1.0125
1.001
1.002
1.003
3.64
1.011
1.0022
3.33
3.06
1.0015
1.0029
1.002
1.008
1.016
1.002
1.008
1.016
1.0000
1.0037
1.0090
1.003
1.0046
1.005
Table 23 Representative CPU Thermal Diode
and Transistor Non-Ideality Factors
CPU or ASIC Substrate Remote Diodes
A substrate diode is a parasitic PNP transistor that has its
collector tied to ground through the substrate and the
base (D-) and emitter (D+) brought out to pins.
Connection to these pins is shown in Figure 11. The non-
ideality figures in Table 23 include the effects of any
package resistance and represent the value seen from
the CPU socket. The temperature indicated will need to
be compensated for the departure from a non-ideality of
1.008.
D+
D-
CPU
aSC7512
Substrate
Figure 11 CPU Remote Diode Connection
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| ASC7512M8 | DIGITAL TEMPERATURE SENSOR WITH INTEGRATED FAN CONTROL |
| ASC7521A | LOW- OLTAGE 1-WIRE DIGITAL TEMPERATURE SENSOR |
| ASC7521AM8 | LOW- OLTAGE 1-WIRE DIGITAL TEMPERATURE SENSOR |
| ASC7531A | LOW-VOLTAGE 1-WIRE DIGITAL TEMPERATURE SENSOR AND VOLTAGE MONITOR |
| ASC7531AM10 | LOW-VOLTAGE 1-WIRE DIGITAL TEMPERATURE SENSOR AND VOLTAGE MONITOR |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| ASC7512M8 | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:DIGITAL TEMPERATURE SENSOR WITH INTEGRATED FAN CONTROL |
| ASC7521A | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:LOW- OLTAGE 1-WIRE DIGITAL TEMPERATURE SENSOR |
| ASC7521AM8 | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:LOW- OLTAGE 1-WIRE DIGITAL TEMPERATURE SENSOR |
| ASC7531A | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:LOW-VOLTAGE 1-WIRE DIGITAL TEMPERATURE SENSOR AND VOLTAGE MONITOR |
| ASC7531AM10 | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:LOW-VOLTAGE 1-WIRE DIGITAL TEMPERATURE SENSOR AND VOLTAGE MONITOR |
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