XTR110 is the precise voltage/electric current converter which American Burr - Brown Corporation promotes, it is designs specially for the simulated signal transmission. May use in 0~5V either the 0~10V input voltage transforms 4~20mA 0~20mA,5~25mA or other commonly used scope output current. In addition, its internal precise 10V reference voltage may also use in actuating the exterior electric circuit.
This chip by the precision resistor network module, the voltage/current transformation module, the electric current/current transformation module and the precise 10V voltage datum module is composed. Because it uses the electric current to carry on the transmission, can therefore overcome effectively in the long-line transmission process the environment disturbance to the test the influence, thus makes its performance to enhance greatly.
The XTR110 application scope is extremely broad, may use in any need signal processing the situation, particularly in the signal is small, the environment bad testing environment (for example commercial run control, pressure, temperature, strain measured that heavy, data acquisition system and in micro controller application system’s input channel and so on) under is more suitable.
1 pin function
XTR110 pin arrangement as shown in Figure 1.
2 performance parameters
The XTR110 main performance characteristic is as follows:
* uses the standard 4~20mA electric current transmission;
* the input/output range may choose;
* the biggest misalignment error is 0.005%;
* has the precise 10V reference voltage output;
* uses the independent power supply working pattern, and the voltage range is very wide (13.5V~40V);
* the pin is programmable.
Figure 2
3 model application electric circuit
Figure 2 is the 0~10V input corresponds to the 4~20mA output when 煟 the high-rising abundant remote guarantees dark grave Delta Yun pinworm oneself to steal low-lying village liao to meet the electric circuit strict. 熆 sieves regarding other input voltage and the output current scope 熓 coat meng hail according to the special details change base pin 3, 4, 5, 9, 10 connection modes.
The XTR110 output current available equation below indicated:
IO=10 (VREFIN/16 VIN1/4 VIN2/2) /RSPAN
In Figure 2, RSPAN in fact is internal 50Ω resistance R9. In order to obtain the different output current scope, may also connect corresponding exterior RSPAN. But exterior transistor QEXT uses in conducting the signal current output. The recommendation uses P the trench MOS transistor. Its voltage nominal value must be bigger than or be equal to the biggest supply voltage, if supply voltage Vcc has surpassed its electronics grid breakdown voltage, the QEXT drain electrode will be penetrated, but stall.
If internal arithmetic amplifier A1 (Figure 2 left under operational amplifier) the non-inversion input is lower than (0V) above voltage 0.5V, this operational amplifier damages on the possibility. This kind of situation appears generally in the XTR110 base pin 3, 4 or 5 is actuated by an unusual circumstance in reverse swinging operational amplifier time. If necessary, may connects a clamp diode between the reverse input and the place to come to the voltage to carry on the clamp.
The reference voltage should calibrate precisely in base pin 12. In order to maintain the precision, should be connected including base pin 3 any load with this spot.
As shown in Figure 3, may also use voltage divider R1 to adjust the bias electric current. But first should the input voltage reset, then adjust R1 to cause the output current is 4mA. Regarding the output current scope initial value is the 0mA situation, the available following specific step carries on the adjustment: Soon the input voltage adjusts to a very small non-zero value, then adjusts the output current which R1 obtains needs. Thus, when the input will be the zero hour, the output also will be zero.
Using Figure 3 voltage divider R2 may when the output current full scale division carries on the amplitude adjustment. This adjustment and the bias current regulation is the interaction. Regarding this electric circuit, may put in the input voltage the 10V full scale division, then adjusts R2 to the 20mA full scale division output. Uses in the amplitude adjustment R2, R3 and the R4 value should act according to the following principle selection: Chooses R4 to enable the scope to be possible the continual small scale to decrease progressively, then chooses R2 and R3 causes the scope rise, thus causes the scope to be opposite in the central value adjustable.
