datasheetsensor
I have this pressure sensor with the following details from the datasheet:
The diagram for connections is given as follows as Vsupply, GND and Vout:
But the chip has 6 legs and described as follows:
1-) What is V1, V2 and Vex?
2-) And how can I obtain the transfer function equation? Is it Vout = Vs* (.009*P-.095) ± Error ?
How do i measure RL and VRL?
They're noted on page 2 of the datasheet you linked. RL is your 10k resistor. VRL is the voltage developed across it. VC is the sensor's supply voltage (note that the heater (VH) must be 5V +/-5%, but VC can be up to 15V max per the datasheet).
Furthermore, in order to obtain Ro, do i need to run a control, and record RL in clean air and assign Ro to that value?
The datasheet defines Ro as "Sensor resistance in clean air". So if you require Ro, it would appear that you need a sensor exposed to clean air. I'd suggest chatting with the manufacturer as to whether your application requires a) continuous operation of a clean air reference sensor, b) if it's just a one-time calibration step, or c) if it can be done empirically.
"ALS" does not stand for "A low sense", it stands for "A low source". The two lines ALS and BLS provide the means to reference the MOSFET gate drives to the sources of the respective MOSFETs. They are not typically connected to ground. It is expected that there will be current sense resistors to ground. The outputs of these resistors, properly conditioned, are fed back to the input comparator to control the cycling of the bridge.
Best Answer
The fact that the pins are listed by name in the package spec, but not further defined, indicates to me that they're either ports for automated end-of-line testing or for diagnostic purposes. Less likely, but quite possible, is that they're special purpose functions such as fine adjustments or reference voltages that are used only internally or by a few select customers. In any case, the only advice given is on page 4, where they're listed as no connects. I'd take that to the bank, as it's possible that some connected conditions could damage the sensor.
The transfer function you listed agreed with the one on page 5, and matches the graph as well as the specs table. Since it's directly proportional to Vs, if you want good accuracy you should regulate Vs pretty tightly, or alternatively use Vs as a reference to your ADC if you're digitizing the output.