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參數(shù)資料
| 型號： | MAX6640AEE+ |
| 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： | ROHS COMPLIANT, QSOP-16 |
| 文件頁數(shù)： | 10/21頁 |
| 文件大?。?/td> | 215K |
| 代理商： | MAX6640AEE+ |
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 10μA and
100μA, change in the measured voltage is:
ΔVM = RS (100μA - 10μA) = 90μA x RS
Since 1°C corresponds to 198.6μV, series resistance
contributes a temperature offset of:
Assume that the diode being measured has a series
resistance of 3
Ω. 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
Ω, 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
Ω×
°
Ω
=°
..
C
90
198 6
0 453
μ
Ω
μ
°
=
°
Ω
V
C
.
TT
n
T
ACTUAL
M
NOMINAL
M
=
=
1
1 008
1 002
.
= TM(.
)
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.
AMD Athlon is a registered trademark of Advanced Micro
Devices, Inc.
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| MAX6640AEE+ | 功能描述:板上安裝溫度傳感器 Sensors, Transducers 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 |
| MAX6640AEE+T | 功能描述:板上安裝溫度傳感器 Sensors, Transducers 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 |
| MAX6640AEE-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 | 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 |
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