- 您現(xiàn)在的位置：買賣IC網(wǎng) > PDF目錄372951 > XTR104BP 4-20mA Current Transmitter with BRIDGE EXCITATION AND LINEARIZATION PDF資料下載
參數(shù)資料
| 型號： | XTR104BP |
| 英文描述： | 4-20mA Current Transmitter with BRIDGE EXCITATION AND LINEARIZATION |
| 中文描述： | 4 - 20mA電流變送器的電橋的激勵和線性化 |
| 文件頁數(shù)： | 7/11頁 |
| 文件大?。?/td> | 165K |
| 代理商： | XTR104BP |
7
XTR104
BRIDGE BALANCE
Figure 1 shows a bridge trim circuit (R
1
, R
2
). This adjust-
ment can be used to compensate for the initial accuracy of
the bridge and/or to trim the offset voltage of the XTR104.
The values of R
1
and R
2
depend on the impedance of the
bridge, and the trim range required. This trim circuit places
an additional load on the V
R
output. The effective load of the
trim circuit is nearly equal to R
2
. Total load on the V
R
output
terminal must not exceed 2mA. An approximate value for R
1
can be calculated:
5V R
B
4 V
TRIM
(3)
Where: R
B
is the resistance of the bridge.
V
TRIM
is the desired
±
voltage trim range (in V).
Make R
2
equal or lower in value to R
1
.
Figure 2 shows another way to adjust zero errors using the
output current adjustment pins of the XTR104. This pro-
vides
±
500
μ
A (typical) adjustment around the initial low-
scale output current. This is an output current adjustment
that is independent of the input stage gain set with R
G
. If the
input stage is set for high gain the output current adjustment
may not provide sufficient range.
With V
+LIN
and V
–LIN
connected to the bridge output, the
bridge excitation voltage can be made to vary as much as
±
0.5V in response to the bridge output voltage. Be sure that
the total load on the V
R
output is less than 2mA at the
maximum excitation voltage, V
R
= 5.5V.
Signal-dependent variation of the bridge excitation voltage
provides a second-order term to the complete transfer func-
tion (including the bridge). This can be tailored to correct for
bridge sensor nonlinearity. Either polarity of nonlinearity
(bowing up or down) can be compensated by proper connec-
tion of the V
LIN
inputs. Connecting V
+LIN
to V
+IN
and V
–LIN
to V
–IN
(Figure 1) causes V
R
to increase with bridge output
which compensates for a positive bow in the bridge re-
sponse. Reversing the connections (Figure 3) causes V
R
to
decrease with increasing bridge output, to compensate for
negative-bowing nonlinearity.
To determine the required value for R
LIN
you must know the
nonlinearity of the bridge sensor with constant excitation
voltage. The linearization circuitry can only compensate for
the parabolic portion of a sensor’s nonlinearity. Parabolic
nonlinearity has a maximum deviation from linear occurring
at mid-scale (see Figure 4). Sensors with nonlinearity curves
similar to that shown in Figure 4, but not peaking exactly at
mid-scale can be substantially improved. A nonlinearity that
is perfectly “S-shaped” (equal positive and negative
nonlinearity) cannot be corrected with the XTR104. It may,
however, be possible to improve the worst-case nonlinearity
of a sensor by equalizing the positive and negative
nonlinearity.
The nonlinearity, B (in % of full scale), is positive or
negative depending on the direction of the bow. A maximum
of
±
2.5% nonlinearity can be corrected. An approximate
value for R
LIN
can be calculated by:
K
LIN
V
FS
(5)
Where: K
LIN
≈
24000.
V
FS
is the full-scale bridge output (in Volts) with
constant 5V excitation.
B is the parabolic nonlinearity in
±
% of full scale.
R
LIN
in
.
Methods for refining this calculation involve determining
the actual value of K
LIN
for a particular device (explained
later).
B is a signed number (negative for a downward-bowing
nonlinearity). This can produce a negative value for R
LIN
. In
this case, use the resistor value indicated (ignore the sign),
but connect V
+LIN
to V
–IN
and V
–LIN
to V
+IN
as shown in
Figure 3.
This approximate calculation of R
LIN
generally provides
about a 5:1 improvement in bridge nonlinearity.
Example:
The bridge sensor depicted by the negative-
bowing curve in Figure 4. Its full scale output is 10mV with
constant 5V excitation. Its maximum nonlinearity, B, is
–1.9% referred to full scale (occurring at mid-scale). Using
equation 5:
R
1
≈
15
14
XTR104
16
10k
XTR104
5k
5k
16
(a)
(b)
15
14
±500μA typical
output current
adjustment range.
±50μA typical
output current
adjustment range.
FIGURE 2. Low-scale Output Current Adjustment.
R
LIN
=
0.2 B
LINEARIZATION
Differential voltage applied to the linearization inputs, V
+LIN
and V
–LIN
, causes the reference (excitation) voltage, V
R
, to
vary according to the following equation:
(4)
Where: V
LIN
is the voltage applied to the V
+LIN
and V
–LIN
differential inputs (in V).
R
LIN
in
.
K
LIN
≈
24000 (approximately
±
20% depending on
variations in the fabrication of the XTR104).
V
R
=
5V
+
V
LIN
K
LIN
R
LIN
相關PDF資料 |
PDF描述 |
|---|---|
| XTR104BU | A/D Converter (A-D) IC; Resolution (Bits):16; Sample Rate:100SPS; Input Channels Per ADC:1; Input Channel Type:Differential; Data Interface:Serial; Package/Case:20-SOIC; DNL +/-:0.5LSB; Leaded Process Compatible:No; No. of Bits:16 RoHS Compliant: No |
| XTR106 | A/D Converter (A-D) IC; Resolution (Bits):16; Sample Rate:212SPS; Input Channels Per ADC:1; Input Channel Type:Differential; Data Interface:Serial; Package/Case:8-SOIC; Leaded Process Compatible:No; No. of Bits:18 RoHS Compliant: Yes |
| XTR106P | A/D Converter (A-D) IC; Resolution (Bits):16; Sample Rate:100SPS; Input Channels Per ADC:1; Input Channel Type:Differential; Data Interface:Serial; Package/Case:8-SOIC; Leaded Process Compatible:No; No. of Bits:18 RoHS Compliant: Yes |
| XTR106PA | A/D Converter (A-D) IC; Resolution (Bits):20; Sample Rate:100SPS; Input Channels Per ADC:1; Input Channel Type:Differential; Data Interface:Serial; Package/Case:8-SOIC; Interface Type:Serial; Leaded Process Compatible:No RoHS Compliant: Yes |
| XTR106U | A/D Converter (A-D) IC; Resolution (Bits):16; Sample Rate:60SPS; Input Channels Per ADC:1; Input Channel Type:Differential; Data Interface:Serial, 3/4/5-Wire; Package/Case:; DNL +/-:0.5LSB; Interface Type:Serial RoHS Compliant: No |
相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| XTR104BU | 制造商:Texas Instruments 功能描述: |
| XTR105 | 制造商:BB 制造商全稱:BB 功能描述:4-20mA CURRENT TRANSMITTER with Sensor Excitation and Linearization |
| XTR105-DIE | 制造商:TI 制造商全稱:Texas Instruments 功能描述:4-20mA CURRENT TRANSMITTER WITH SENSOR EXCITATION AND LINEARIZATION |
| XTR105P | 功能描述:電流靈敏放大器 4-20mA Crnt Trnsmtr w/Sensor Exc & Lin RoHS:否 制造商:Texas Instruments 通道數(shù)量: 共模抑制比（最小值）:110 dB 輸入補償電壓:80 uV 電源電壓-最大:5.5 V 電源電壓-最小:2.7 V 電源電流:350 uA 最大工作溫度:+ 125 C 最小工作溫度:- 40 C 安裝風格:SMD/SMT 封裝 / 箱體:VQFN-16 封裝:Reel |
| XTR105PA | 功能描述:電流靈敏放大器 4-20mA Crnt Trnsmtr w/Sensor Exc & Lin RoHS:否 制造商:Texas Instruments 通道數(shù)量: 共模抑制比（最小值）:110 dB 輸入補償電壓:80 uV 電源電壓-最大:5.5 V 電源電壓-最小:2.7 V 電源電流:350 uA 最大工作溫度:+ 125 C 最小工作溫度:- 40 C 安裝風格:SMD/SMT 封裝 / 箱體:VQFN-16 封裝:Reel |
發(fā)布緊急采購，3分鐘左右您將得到回復。