- 您現(xiàn)在的位置：買賣IC網(wǎng) > PDF目錄358861 > LM40 (National Semiconductor Corporation) Hardware Monitor with Dual Thermal Diodes and SensorPath Bus PDF資料下載
參數(shù)資料
| 型號： | LM40 |
| 廠商： | National Semiconductor Corporation |
| 英文描述： | Hardware Monitor with Dual Thermal Diodes and SensorPath Bus |
| 中文描述： | 硬件監(jiān)控雙熱二極管和SensorPath總線 |
| 文件頁數(shù)： | 24/27頁 |
| 文件大?。?/td> | 369K |
| 代理商： | LM40 |
第1頁第2頁第3頁第4頁第5頁第6頁第7頁第8頁第9頁第10頁第11頁第12頁第13頁第14頁第15頁第16頁第17頁第18頁第19頁第20頁第21頁第22頁第23頁當(dāng)前第24頁第25頁第26頁第27頁
2.0 Register Set
(Continued)
Bit
7-2
Type
RO
Description
Reserved.
Will always read "0".
Conversion Rate Control
LowPwr
0
1
0
1
0
1
0
1
[CR1:CR0]
00
00
01
01
10
10
11
11
Typical Conversion Rate (ms)
Fastest*: continuous
91
91
364
182 (default)
728
364
1456
*Fastest: 2x7.5ms(remote) + 7.5msec (local) + 5x1.42msec (voltage) = 29.6 ms total
The sensor conversion rate is controlled by this register as well as the Low Power Bit of Device Control Register. This register is
not defined by the SensorPath specification. Therefore, on a motherboard when using a Super I/O host this register must be
modified during BIOS run time. The conversion rate is dependent on system physical requirements and limitations. The thermal
response time of the MSOP package is one such requirement. Most systems will function properly with the default settings. The
master scan rate is related to the conversion rate of the LM40. If attentions are enabled the conversion rate and scan rate will be
equal.
3.0 Application Hints
The LM40 can be applied easily in the same way as other
integrated-circuit temperature sensors, and its remote diode
sensing capability allows it to be used in new ways as well.
It can be soldered to a printed circuit board, and because the
path of best thermal conductivity is between the die and the
pins, its temperature will effectively be that of the printed
circuit board lands and traces soldered to the LM40’s pins.
This presumes that the ambient air temperature is almost the
same as the surface temperature of the printed circuit board;
if the air temperature is much higher or lower than the
surface temperature, the actual temperature of the of the
LM40 die will be at an intermediate temperature between the
surface and air temperatures. Again, the primary thermal
conduction path is through the leads, so the circuit board
temperature will contribute to the die temperature much
more strongly than will the air temperature.
To measure temperature external to the LM40’s die, use a
remote diode. This diode can be located on the die of a
target IC, allowing measurement of the IC’s temperature,
independent of the LM40’s temperature. The LM40 has been
optimized to measure the remote diode of a 90 nm Pentium
4 processor as shown in
Figure 7
. A discrete diode can also
be used to sense the temperature of external objects or
ambient air. Remember that a discrete diode’s temperature
will be affected, and often dominated, by the temperature of
its leads.
Most silicon diodes do not lend themselves well to this
application. It is recommended that a 2N3904 transistor
base emitter junction be used with the collector tied to the
base.
A diode connected 2N3904 approximates the junction avail-
able on a Pentium microprocessor for temperature measure-
ment. Therefore, the LM40 can sense the temperature of this
diode effectively. Although, an offset will be observed. The
temperature reading will be offset by approximately 4.5C,
therefore a correction factor of +4.5C should be added to all
temperature readings when using a 2N3904 transistor.
20068415
FIGURE 7. 90 nm Pentium 4 Temperature vs LM40
Temperature Reading
L
www.national.com
24
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| LM4120AIM5X-5.0 | Precision Micropower Low Dropout Voltage Reference |
| LM4120AIM5-1.8 | Precision Micropower Low Dropout Voltage Reference |
| LM4120AIM5-3.3 | Precision Micropower Low Dropout Voltage Reference |
| LM4120AIM5X-2.5 | Precision Micropower Low Dropout Voltage Reference |
| LM4120AIM5X-3.3 | Precision Micropower Low Dropout Voltage Reference |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LM400 | 制造商:LM TECHNOLOGIES 功能描述:MODULE BLUETOOTH V2.0 CLASS 1 BC04 制造商:LM TECHNOLOGIES 功能描述:BLUETOOTH MODULE, BC04, CLASS 1, EDR 制造商:LM TECHNOLOGIES 功能描述:BLUETOOTH MOD, PDA, GPS, POS, BC04, CLASS 1, EDR; Supply Voltage Min:2.7V; Supply Voltage Max:3.6V; Data Rate:3Mbps; Bluetooth Version:Bluetooth 2.0 + EDR; Bluetooth Class:Class 1; Receive Sensitivity:-88dBm; Type:Bluetooth Module ;RoHS Compliant: Yes |
| LM4001 | 制造商:SEMTECH_ELEC 制造商全稱:SEMTECH ELECTRONICS LTD. 功能描述:SURFACE MOUNT SILICON RECTIFIERS |
| LM4001G | 制造商:SEMTECH_ELEC 制造商全稱:SEMTECH ELECTRONICS LTD. 功能描述:SURFACE MOUNT GLASS PASSIVATED SILICON RECTIFIERS |
| LM4002 | 制造商:SEMTECH_ELEC 制造商全稱:SEMTECH ELECTRONICS LTD. 功能描述:SURFACE MOUNT SILICON RECTIFIERS |
| LM4002G | 制造商:SEMTECH_ELEC 制造商全稱:SEMTECH ELECTRONICS LTD. 功能描述:SURFACE MOUNT GLASS PASSIVATED SILICON RECTIFIERS |
發(fā)布緊急采購，3分鐘左右您將得到回復(fù)。