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參數(shù)資料
| 型號： | MAX6640AEE+T |
| 廠商： | MAXIM INTEGRATED PRODUCTS INC |
| 元件分類： | 模擬信號調(diào)理 |
| 英文描述： | 2-Channel Temperature Monitor with Dual Automatic PWM Fan-Speed Controller |
| 中文描述： | SPECIALTY ANALOG CIRCUIT, PDSO16 |
| 封裝： | 0.150 INCH, 0.025 INCH PITCH, ROHS COMPLIANT, MO-137AB, QSOP-16 |
| 文件頁數(shù)： | 10/24頁 |
| 文件大?。?/td> | 428K |
| 代理商： | MAX6640AEE+T |
MAX6640
Effect of Ideality Factor
The accuracy of the remote temperature measurements
depends on the ideality factor (n) of the remote diode
(actually a transistor). The MAX6640 is optimized for n
= 1.008, which is the typical value for the Intel
Pentium III and the AMD Athlon MP model 6. If a
sense transistor with a different ideality factor is used,
the output data is different. Fortunately, the difference
is predictable.
Assume a remote-diode sensor designed for a nominal
ideality factor nNOMINAL is used to measure the tem-
perature of a diode with a different ideality factor, n1.
The measured temperature TM can be corrected using:
where temperature is measured in Kelvin.
As mentioned above, the nominal ideality factor of the
MAX6640 is 1.008. As an example, assume the
MAX6640 is configured with a CPU that has an ideality
factor of 1.002. If the diode has no series resistance,
the measured data is related to the real temperature
as follows:
For a real temperature of +85°C (358.15K), the mea-
sured temperature is +82.91°C (356.02K), which is an
error of -2.13°C.
Effect of Series Resistance
Series resistance in a sense diode contributes addition-
al errors. For nominal diode currents of 10A and
100A, change in the measured voltage is:
VM = RS (100A - 10A) = 90A x RS
Since 1°C corresponds to 198.6V, series resistance
contributes a temperature offset of:
Assume that the diode being measured has a series
resistance of 3. The series resistance contributes an
offset of:
The effects of the ideality factor and series resistance
are additive. If the diode has an ideality factor of 1.002
and series resistance of 3, the total offset can be cal-
culated by adding error due to series resistance with
error due to ideality factor:
1.36°C - 2.13°C = -0.77°C
for a diode temperature of +85°C.
In this example, the effect of the series resistance and
the ideality factor partially cancel each other.
For best accuracy, the discrete transistor should be a
small-signal device with its collector connected to GND
and base connected to DXN. Table 11 lists examples of
discrete transistors that are appropriate for use with the
MAX6640.
3
0 453
1 36
×
°
=°
.
C
90
198 6
0 453
°
=
°
V
C
.
TT
n
TT
ACTUAL
M
NOMINAL
MM
=
=
=
1
1 008
1 002
1 00599
.
(.
)
TT
n
M
ACTUAL
NOMINAL
=
1
2-Channel Temperature Monitor with Dual
Automatic PWM Fan-Speed Controller
18
______________________________________________________________________________________
FIGURE
DESCRIPTION
PULSE STRETCHING
PWM FREQUENCY
PWM POLARITY
6
High-side PWM drive
Yes
Low
Negative
7
Low-side PWM drive
Yes
Low
Positive
8
High-side PWM drive with keep-alive supply
No
Low
Negative
9
High-side linear supply
No
High
Positive
10
4-wire fan with PWM speed-control input
No
High
Positive
Table 10. Summary of Fan-Drive Options
MANUFACTURER
MODEL NO.
Central Semiconductor (USA)
CMPT3906
Rohm Semiconductor (USA)
SST3906
Samsung (Korea)
KST3906-TF
Siemens (Germany)
SMBT3906
Table 11. Remote-Sensor Transistor
Manufacturers
Intel and Pentium are registered trademarks of Intel Corp.
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| MAX6640ATE | 功能描述:板上安裝溫度傳感器 RoHS:否 制造商:Omron Electronics 輸出類型:Digital 配置: 準(zhǔn)確性:+/- 1.5 C, +/- 3 C 溫度閾值: 數(shù)字輸出 - 總線接口:2-Wire, I2C, SMBus 電源電壓-最大:5.5 V 電源電壓-最小:4.5 V 最大工作溫度:+ 50 C 最小工作溫度:0 C 關(guān)閉: 安裝風(fēng)格: 封裝 / 箱體: 設(shè)備功能:Temperature and Humidity Sensor |
| MAX6640ATE+T | 功能描述:板上安裝溫度傳感器 RoHS:否 制造商:Omron Electronics 輸出類型:Digital 配置: 準(zhǔn)確性:+/- 1.5 C, +/- 3 C 溫度閾值: 數(shù)字輸出 - 總線接口:2-Wire, I2C, SMBus 電源電壓-最大:5.5 V 電源電壓-最小:4.5 V 最大工作溫度:+ 50 C 最小工作溫度:0 C 關(guān)閉: 安裝風(fēng)格: 封裝 / 箱體: 設(shè)備功能:Temperature and Humidity Sensor |
| MAX6640ATE-T | 功能描述:板上安裝溫度傳感器 RoHS:否 制造商:Omron Electronics 輸出類型:Digital 配置: 準(zhǔn)確性:+/- 1.5 C, +/- 3 C 溫度閾值: 數(shù)字輸出 - 總線接口:2-Wire, I2C, SMBus 電源電壓-最大:5.5 V 電源電壓-最小:4.5 V 最大工作溫度:+ 50 C 最小工作溫度:0 C 關(guān)閉: 安裝風(fēng)格: 封裝 / 箱體: 設(shè)備功能:Temperature and Humidity Sensor |
| MAX6640EVCMOD2 | 功能描述:板上安裝溫度傳感器 Evaluation System/Evaluation Kit for the MAX6640 RoHS:否 制造商:Omron Electronics 輸出類型:Digital 配置: 準(zhǔn)確性:+/- 1.5 C, +/- 3 C 溫度閾值: 數(shù)字輸出 - 總線接口:2-Wire, I2C, SMBus 電源電壓-最大:5.5 V 電源電壓-最小:4.5 V 最大工作溫度:+ 50 C 最小工作溫度:0 C 關(guān)閉: 安裝風(fēng)格: 封裝 / 箱體: 設(shè)備功能:Temperature and Humidity Sensor |
| MAX6640EVKIT | 功能描述:板上安裝溫度傳感器 Evaluation System/Evaluation Kit for the MAX6640 RoHS:否 制造商:Omron Electronics 輸出類型:Digital 配置: 準(zhǔn)確性:+/- 1.5 C, +/- 3 C 溫度閾值: 數(shù)字輸出 - 總線接口:2-Wire, I2C, SMBus 電源電壓-最大:5.5 V 電源電壓-最小:4.5 V 最大工作溫度:+ 50 C 最小工作溫度:0 C 關(guān)閉: 安裝風(fēng)格: 封裝 / 箱體: 設(shè)備功能:Temperature and Humidity Sensor |
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