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參數資料
| 型號： | XTR106PA |
| 元件分類： | 運動控制電子 |
| 英文描述： | 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 |
| 中文描述： | 的4 - 20mA的電橋激勵和線性電流變送器 |
| 文件頁數： | 10/15頁 |
| 文件大?。?/td> | 272K |
| 代理商： | XTR106PA |
10
XTR106
R
1
≈
5V
R
B
4
V
TRIM
EXTERNAL TRANSISTOR
External pass transistor, Q
1
, conducts the majority of the
signal-dependent 4-20mA loop current. Using an external
transistor isolates the majority of the power dissipation from
the precision input and reference circuitry of the XTR106,
maintaining excellent accuracy.
Since the external transistor is inside a feedback loop its
characteristics are not critical. Requirements are: V
CEO
= 45V
min,
β
= 40 min and P
D
= 800mW. Power dissipation require-
ments may be lower if the loop power supply voltage is less
than 36V. Some possible choices for Q
1
are listed in Figure 1.
The XTR106 can be operated without an external pass
transistor. Accuracy, however, will be somewhat degraded
due to the internal power dissipation. Operation without Q
1
is not recommended for extended temperature ranges. A
resistor (R = 3.3k
) connected between the I
RET
pin and the
E (emitter) pin may be needed for operation below 0
°
C
without Q
1
to guarantee the full 20mA full-scale output,
especially with V+ near 7.5V.
The low operating voltage (7.5V) of the XTR106 allows
operation directly from personal computer power supplies
(12V
±
5%). When used with the RCV420 Current Loop
Receiver
(Figure 8), load resistor voltage drop is limited to 3V.
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 XTR106.
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
REF
output. Be sure the additional
load on V
REF
does not affect zero output. See the Typical
Performance Curve, “Under-Scale Current vs I
REF
+ I
REG
.”
The effective load of the trim circuit is nearly equal to R
2
.
An approximate value for R
1
can be calculated:
(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
.
LINEARIZATION
Many bridge sensors are inherently nonlinear. With the
addition of one external resistor, it is possible to compensate
for parabolic nonlinearity resulting in up to 20:1 improve-
ment over an uncompensated bridge output.
Linearity correction is accomplished by varying the bridge
excitation voltage. Signal-dependent variation of the bridge
excitation voltage adds a second-order term to the overall
transfer function (including the bridge). This can be tailored
to correct for bridge sensor nonlinearity.
Either positive or negative bridge non-linearity errors can be
compensated by proper connection of the Lin Polarity pin.
To correct for positive bridge nonlinearity (upward bowing),
Lin Polarity (pin 12) should be connected to I
RET
(pin 6) as
shown in Figure 3a. This causes V
REF
to increase with bridge
output which compensates for a positive bow in the bridge
response. To correct negative nonlinearity (downward bow-
ing), connect Lin Polarity to V
REG
(pin 1) as shown in Figure
3b. This causes V
REF
to decrease with bridge output. The Lin
Polarity pin is a high impedance node.
If no linearity correction is desired, both the R
LIN
and Lin
Polarity pins should be connected to V
REG
(Figure 3c). This
results in a constant reference voltage independent of input
signal.
R
LIN
or Lin Polarity pins should not be left open
or connected to another potential.
R
LIN
is the external linearization resistor and is connected
between pin 11 and pin 1 (V
REG
) as shown in Figures 3a and
3b. To determine the value of R
LIN
, the nonlinearity of the
bridge sensor with constant excitation voltage must be
known. The XTR106’s linearity circuitry can only compen-
sate for the parabolic-shaped portions of a sensor’s
nonlinearity. Optimum correction occurs when maximum
deviation from linear output occurs at mid-scale (see Figure
4). Sensors with nonlinearity curves similar to that shown in
LOOP POWER SUPPLY
The voltage applied to the XTR106, V+, is measured with
respect to the I
O
connection, pin 7. V+ can range from 7.5V
to 36V. The loop supply voltage, V
PS
, will differ from the
voltage applied to the XTR106 according to the voltage drop
on the current sensing resistor, R
L
(plus any other voltage
drop in the line).
If a low loop supply voltage is used, R
L
(including the loop
wiring resistance) must be made a relatively low value to
assure that V+ remains 7.5V or greater for the maximum
loop current of 20mA:
(2)
It is recommended to design for V+ equal or greater than
7.5V with loop currents up to 30mA to allow for out-of-
range input conditions. V+ must be at least 8V if 5V sensor
excitation is used and if correcting for bridge nonlinearity
greater than +3%.
R
L
max
=
(V
+
) – 7.5V
20mA
– R
WIRING
8
XTR106
0.01μF
E
I
O
I
RET
V+
10
7
6
R
Q
= 3.3k
For operation without external
transistor, connect a 3.3k
resistor between pin 6 and
pin 8. See text for discussion
of performance.
FIGURE 2. Operation without External Transistor.
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| 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 |
| XTR106UA | A/D Converter (A-D) IC; Resolution (Bits):16; ADC Sample Rate:60SPS; Input Channels Per ADC:1; Input Channel Type:Differential Inputs; DNL +/-:0.5LSB; Data Interface:Serial, 3/4/5-Wire; Package/Case:24-SOIC |
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相關代理商/技術參數 |
參數描述 |
|---|---|
| XTR106PA | 制造商:Texas Instruments 功能描述:Transceiver IC |
| XTR106PAG4 | 功能描述:電流靈敏放大器 4-20mA Crnt Trnsmtr w/Bridger Exc & Lin RoHS:否 制造商:Texas Instruments 通道數量: 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 |
| XTR106PG4 | 功能描述:電流靈敏放大器 4-20mA Crnt Trnsmtr w/Bridger Exc & Lin RoHS:否 制造商:Texas Instruments 通道數量: 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 |
| XTR106U | 功能描述:電流靈敏放大器 4-20mA Crnt Trnsmtr w/Bridger Exc & Lin RoHS:否 制造商:Texas Instruments 通道數量: 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 |
| XTR106U | 制造商:Texas Instruments 功能描述:CURRENT LOOP TRANSMITTER SOIC14 |
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