The USC701 is combined with the Resistance Simulator to convert an analogue signal (or sensor input) to a resistance output. The example below shows the conversion of a 0-10Vdc representing a temperature range into a resistance output to simulate a thermistor
The USC701 converts the input signal with the necessary linearisation to a pulse width modulated signal that adjusts the SPL0627B resistance to the required output.
The pulse width modulated control signal input to the SPL627B has a defined nonlinear relationship with the resistance output. The USC701 performs all the necessary calculations to ensure the correct output is generated.
Input 0-10V wants output resistance equivalent to -35...+25°C.
The relationship of res vs temp in given in table.
For a particular voltage Vx input,the USC scales the equivalent temperature; the table gives Rx. SPL0627 needs G=0 for res 'a', G=1 for res b.
For res Rx, need G=(Rx-a)/b-a).
Out is scaled 0..100%PWM for G=0..1
| res | degC |
|---|---|
| 4.7 | 25 |
| 5.869 | 20 |
| 7.378 | 15 |
| 9.34 | 10 |
| 11.91 | 5 |
| 15.3 | 0 |
| 19.81 | -5 |
| 25.87 | -10 |
| 34.08 | -15 |
| 45.3 | -20 |
| 60.77 | -25 |
| 82.35 | -30 |
| 112.8 | -35 |
General Limitations
| Maximum output voltage across simulated R: | 5V |
| Maximum output current across simulated R: | 5mA |
| Note | Output resistance cannot be zero. |
Program
| File | Comment |
|---|---|
 Help |
If unexpected results occur when loading the .usc file press back and click on help for instructions. |
 UAP1068a.usc |
First Issue. |