參數(shù)資料
型號(hào)： LM81CIMTX-3
英文描述： Single-Ended Data Acquisition System
中文描述： 單端數(shù)據(jù)采集系統(tǒng)
文件頁(yè)數(shù)： 18/33頁(yè)
文件大小： 414K
代理商： LM81CIMTX-3
Functional Description
(Continued)
7.0 DAC OUTPUT
The
LM81
Converter) with an output range of 0 to 1.25 volts (4.88 mV
LSB). This DAC can be used in any way, but in most
applications of the LM81 the DAC will be used for fan control.
Typically the DAC output would be amplified to provide the
up to 12 volt drive required by the fan. At power-on the DAC
provides full output, insuring that full fan speed is the default
condition. Care should be taken such that the analog
circuitry tied to this pin does not drive this pin above 2.5V.
Doing so will place the LM81 in NAND tree test mode which
will make all pins inputs, thus disabling any response from
the LM81.
Fans do not start reliably at reduced voltages, so operation
at a reduced voltage should be preceded by a brief (typically
1 second) excursion to full operating voltage, then reduce
the voltage. Most fans do not operate at all below 5 to 7
volts. At those lower voltages the fan will simply consume
current, dissipate power, and not operate and such
conditions should be avoided.
provides
an
8-bit
DAC
(Digital-to-Analog
The output of the amplifier can be configured to provide a
high or low side pass transistor. A high side pass transistor
simplifies the coupling of tachometer outputs to the
tachometer inputs of the LM81 since the fan remains
grounded. Low side drive will require AC coupling along with
clamping at the LM81 input to prevent negative excursions.
A typical circuit for fan drive is shown in Figure 8 R4 is used
when a negative power supply is available to eliminate offset
in the amplifier and provide a 0 to 11.5 volt output (actually
12 volts less saturation). Omitting R4 will create a “dead
zone” between approximately 0 to 6 volts output (a
potentially unusable region anyway). In many applications
protecting the pass transistor Q2 from faults such as a
shorted fan can be accomplished by taking advantage of the
current limit already existing on the 12 volt supply. Q2 will
have to be heat-sunk accordingly. Otherwise, use the
suggested current limit circuit as shown.
DS100072-28
FIGURE 8. Amplifier circuit for connection between DAC output and fan.
L
www.national.com
18
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LM81CIMTX-3/NOPB 功能描述:監(jiān)控電路 RoHS:否 制造商:STMicroelectronics 監(jiān)測(cè)電壓數(shù): 監(jiān)測(cè)電壓: 欠電壓閾值: 過(guò)電壓閾值: 輸出類型:Active Low, Open Drain 人工復(fù)位:Resettable 監(jiān)視器:No Watchdog 電池備用開(kāi)關(guān):No Backup 上電復(fù)位延遲（典型值）:10 s 電源電壓-最大:5.5 V 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:UDFN-6 封裝:Reel
LM81CIMTX-32 制造商:NSC 制造商全稱:National Semiconductor 功能描述:Serial Interface ACPI-Compatible Microprocessor System
LM81DH12 功能描述:基本/快動(dòng)開(kāi)關(guān) Foot Switch RoHS:否 制造商:Omron Electronics 觸點(diǎn)形式:SPDT 執(zhí)行器:Lever 電流額定值:5 A 電壓額定值 AC:250 V 電壓額定值 DC:30 V 功率額定值: 工作力:120 g IP 等級(jí):IP 67 NEMA 額定值: 端接類型:Wire 安裝:Panel
LM8-1M.5M.1 制造商:Banner Engineering 功能描述:LM8-1M.5M.1 LOGIC MOD MULTIBM
LM81-S 功能描述:基本/快動(dòng)開(kāi)關(guān) Foot Switch RoHS:否 制造商:Omron Electronics 觸點(diǎn)形式:SPDT 執(zhí)行器:Lever 電流額定值:5 A 電壓額定值 AC:250 V 電壓額定值 DC:30 V 功率額定值: 工作力:120 g IP 等級(jí):IP 67 NEMA 額定值: 端接類型:Wire 安裝:Panel
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