- 您現(xiàn)在的位置：買賣IC網(wǎng) > PDF目錄44530 > LM334MDC (NATIONAL SEMICONDUCTOR CORP) SPECIALTY ANALOG CIRCUIT, UUC PDF資料下載
參數(shù)資料
| 型號： | LM334MDC |
| 廠商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分類： | 模擬信號調(diào)理 |
| 英文描述： | SPECIALTY ANALOG CIRCUIT, UUC |
| 封裝： | DIE |
| 文件頁數(shù)： | 18/20頁 |
| 文件大?。?/td> | 362K |
| 代理商： | LM334MDC |
Application Hints (Continued)
With the R
1 to R2 ratio determined, values for R1 and R2
should be determined to give the desired set current. The
formula for calculating the set current at T = 25C is shown
below, followed by an example that assumes the forward
voltage drop across the diode (V
D) is 0.6V, the voltage
across R
1 is 67.7mV (64 mV + 5.9% to account for IBIAS),
and R
2/R1 = 10 (from the previous calculations).
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
example will show). For lowest tempco with a specific diode
at the desired I
SET, however, the circuit should be built and
tested over temperature. If the measured tempco of I
SET is
positive, R
2 should be reduced. If the resulting tempco is
negative, R
2 should be increased. The recommended diode
for use in this circuit is the 1N457 because its tempco is
centered at 11 times the tempco of the LM134, allowing R
2 =
10 R
1. 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 R2:
The values of R
1 and R2 can be changed to standard 1%
resistor values (R
1 = 133 and R2 = 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
effective. Assume the tempco of the diode is 2.6mV/C in-
stead 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 = VREF/583A. VREF may be any stable positive voltage ≥ 2V
Trim R3 to calibrate
LM134/LM234/LM334
www.national.com
7
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| LM1524DJ | SWITCHING CONTROLLER, 550 kHz SWITCHING FREQ-MAX, CDIP16 |
| LM1572MTCX-ADJ/NOPB | 3.2 A SWITCHING REGULATOR, 570 kHz SWITCHING FREQ-MAX, PDSO16 |
| LM1572MTCX-5.0/NOPB | 3.2 A SWITCHING REGULATOR, 570 kHz SWITCHING FREQ-MAX, PDSO16 |
| LM1572MTCX-3.3/NOPB | 3.2 A SWITCHING REGULATOR, 570 kHz SWITCHING FREQ-MAX, PDSO16 |
| LM1572MTC-3.3/NOPB | 3.2 A SWITCHING REGULATOR, 570 kHz SWITCHING FREQ-MAX, PDSO16 |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LM334MX | 功能描述:基準(zhǔn)電壓& 基準(zhǔn)電流 RoHS:否 制造商:STMicroelectronics 產(chǎn)品:Voltage References 拓?fù)浣Y(jié)構(gòu):Shunt References 參考類型:Programmable 輸出電壓:1.24 V to 18 V 初始準(zhǔn)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 |
| LM334MX/NOPB | 功能描述:基準(zhǔn)電壓& 基準(zhǔn)電流 RoHS:否 制造商:STMicroelectronics 產(chǎn)品:Voltage References 拓?fù)浣Y(jié)構(gòu):Shunt References 參考類型:Programmable 輸出電壓:1.24 V to 18 V 初始準(zhǔn)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 |
| LM334S8 | 功能描述:IC CURRENT SOURCE 8SOIC RoHS:否 類別:集成電路 (IC) >> PMIC - 穩(wěn)流/電流管理 系列:- 產(chǎn)品培訓(xùn)模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標(biāo)準(zhǔn)包裝:50 系列:- 功能:電流開關(guān) 檢測方法:- 精確度:±10% 輸入電壓:1.7 V ~ 5.5 V 電流 - 輸出:600mA 工作溫度:-40°C ~ 125°C 安裝類型:表面貼裝 封裝/外殼:10-UFQFN 供應(yīng)商設(shè)備封裝:10-UTQFN（1.4x1.8） 包裝:管件 |
| LM334S8#PBF | 功能描述:IC CURRENT SOURCE 8SOIC RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)流/電流管理 系列:- 產(chǎn)品培訓(xùn)模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標(biāo)準(zhǔn)包裝:50 系列:- 功能:電流開關(guān) 檢測方法:- 精確度:±10% 輸入電壓:1.7 V ~ 5.5 V 電流 - 輸出:600mA 工作溫度:-40°C ~ 125°C 安裝類型:表面貼裝 封裝/外殼:10-UFQFN 供應(yīng)商設(shè)備封裝:10-UTQFN（1.4x1.8） 包裝:管件 |
| LM334S8#TR | 功能描述:IC CURRENT SOURCE 8SOIC RoHS:否 類別:集成電路 (IC) >> PMIC - 穩(wěn)流/電流管理 系列:- 產(chǎn)品培訓(xùn)模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標(biāo)準(zhǔn)包裝:50 系列:- 功能:電流開關(guān) 檢測方法:- 精確度:±10% 輸入電壓:1.7 V ~ 5.5 V 電流 - 輸出:600mA 工作溫度:-40°C ~ 125°C 安裝類型:表面貼裝 封裝/外殼:10-UFQFN 供應(yīng)商設(shè)備封裝:10-UTQFN（1.4x1.8） 包裝:管件 |
發(fā)布緊急采購，3分鐘左右您將得到回復(fù)。