MAP Scalar and Offset

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Here is how to calculate the scalar and offset for a MAP sensor.

 

1.Find the minimum and maximum voltage and absolute pressures.
2.Convert the pressures to mbar.
3.Subtract the minimum and maximum voltages to find the range, then do the same for the pressures.
4.Divide the pressure range by the voltage range to calculate the scalar.
5.Multiply the minimum voltage by the scalar to calculate the offset. Note that a positive voltage gives a negative offset.

 

Example for a 3.5 bar MAP sensor:

 

1. For a 3.5 bar data sheet:

0.5V @ 0 kPa (absolute)

4.5V @ 345 kPa (absolute)

 

2. 345 kPa = 3450 mbar.

 

3. Voltage range = 4.0V, pressure range = 3450 mbar.

 

4. 3450 / 4.0 = 862.5 = scalar

 

5. 862.5 x 0.5 x -1 = -431.25 = offset

 

So scalar = 862, offset = -431

 

Plug in the minimum and maximum voltages to check your work:

0.5V x 862.5 - 431.25 = 0 mbar @ 0.5v

4.5V x 862.5 - 431.25 = 3450 mbar @ 0.5v

 

If you have trouble then draw a graph and extrapolate the lines until they cross the pressure axis.