What method do control units typically use to measure RTD sensors ?
I have used NTC thermistors before, consisting of a pull up resistor on an analogue input, but I have never used RTDs before.
Do control units use a special interface to measure RTD sensors, such as a wheatstone bridge or a dedicated IC designed for measuring RTDs ? Or do control units simply use a pull up resistor on an analogue input ?
I understand cost is an important factor in automotive, so thought control units would use the simplest and cheapest method to read RTD sensors.
The CCS connector states two temperatures thresholds:
- 80 degrees C to derate the charging current
90 degrees C to stop charging
- At 80 degrees C the resistance is 1308.97R
At 90 degrees C the resistance is 1347.07R
- At 80 degrees C the voltage drop is 2.835V
At 90 degrees C the voltage drop is 2.870V
There would also need to be hysteresis on each of the two threshold measurements which would be an even smaller voltage.