- 您現(xiàn)在的位置：買賣IC網(wǎng) > PDF目錄358816 > LM234Z-3 (National Semiconductor Corporation) 3-Terminal Adjustable Current Sources PDF資料下載
參數(shù)資料
| 型號： | LM234Z-3 |
| 廠商： | National Semiconductor Corporation |
| 英文描述： | 3-Terminal Adjustable Current Sources |
| 中文描述： | 三端可調(diào)電流源 |
| 文件頁數(shù)： | 7/14頁 |
| 文件大?。?/td> | 273K |
| 代理商： | LM234Z-3 |
Application Hints
(Continued)
This circuit will eliminate most of the LM134’s temperature
coefficient, and it does a good job even if the estimates of the
diode’s characteristics are not accurate (as the following ex-
ample will show). For lowest tempco with a specific diode at
the desired I
, however, the circuit should be built and
tested over temperature. If the measured tempco of I
is
positive, R
2
should be reduced. If the resulting tempco is
negative, R
should be increased. The recommended diode
for use in this circuit is the 1N457 because its tempco is cen-
tered at 11 times the tempco of the LM134, allowing R
= 10
R
. You can also use this circuit to create a current source
with non-zero tempcos by setting the tempco component of
the tempco equation to the desired value instead of 0.
EXAMPLE: A 1mA, Zero-Tempco Current Source
First, solve for R
1
and R
2
:
The values of R
1
and R
2
can be changed to standard 1% re-
sistor values (R
1
= 133
and R
2
= 1.33k
) with less than a
0.75% error.
If the forward voltage drop of the diode was 0.65V instead of
the estimate of 0.6V (an error of 8%), the actual set current
will be
an error of less than 5%.
If the estimate for the tempco of the diode’s forward voltage
drop was off, the tempco cancellation is still reasonably ef-
fective. Assume the tempco of the diode is 2.6mV/C instead
of 2.5mV/C (an error of 4%). The tempco of the circuit is
now:
A 1mA LM134 current source with no temperature compen-
sation would have a set resistor of 68
and a resulting
tempco of
So even if the diode’s tempco varies as much as
±
4% from
its estimated value, the circuit still eliminates 98% of the
LM134’s inherent tempco.
Typical Applications
Ground Referred Fahrenheit Thermometer
DS005697-15
*
Select R3 = V
REF
/583μA. V
REF
may be any stable positive voltage
≥
2V
Trim R3 to calibrate
L
www.national.com
7
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| LM234Z | CAP FILM MKP 1UF 440VAC X1 20% |
| LM234D | THREE TERMINAL ADJUSTABLE CURRENT SOURCES |
| LM234Z-6 | LED 2MM QUAD GREEN |
| LM236 | 2.5-V INTEGRATED REFERENCE CIRCUITS |
| LM236AD | Voltage Reference |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LM234Z-3/NOPB | 功能描述:基準電壓& 基準電流 3-TERM ADJ CURRENT SOURCE RoHS:否 制造商:STMicroelectronics 產(chǎn)品:Voltage References 拓撲結(jié)構(gòu):Shunt References 參考類型:Programmable 輸出電壓:1.24 V to 18 V 初始準確度:0.25 % 平均溫度系數(shù)（典型值）:100 PPM / C 串聯(lián) VREF - 輸入電壓（最大值）: 串聯(lián) VREF - 輸入電壓（最小值）: 分流電流（最大值）:60 mA 最大工作溫度:+ 125 C 封裝 / 箱體:SOT-23-3L 封裝:Reel |
| LM234Z-3/NOPB | 制造商:Texas Instruments 功能描述:Temperature Sensor IC |
| LM234Z-3/T4 | 制造商:Texas Instruments 功能描述:Current Source 3-Pin TO-92 |
| LM234Z-6 | 制造商:National Semiconductor Corporation 功能描述:3-Terminal Adj Current Source National IC TO-92 Plastic |
| LM234Z-6/LFT7 | 功能描述:基準電壓& 基準電流 RoHS:否 制造商:STMicroelectronics 產(chǎn)品:Voltage References 拓撲結(jié)構(gòu):Shunt References 參考類型:Programmable 輸出電壓:1.24 V to 18 V 初始準確度:0.25 % 平均溫度系數(shù)（典型值）:100 PPM / C 串聯(lián) VREF - 輸入電壓（最大值）: 串聯(lián) VREF - 輸入電壓（最小值）: 分流電流（最大值）:60 mA 最大工作溫度:+ 125 C 封裝 / 箱體:SOT-23-3L 封裝:Reel |
發(fā)布緊急采購，3分鐘左右您將得到回復(fù)。