A Ratiometric pressure sensor typically requires a supply voltage of 3V to 5V .They have a voltage output that is proportional to the supply voltage , the output voltage range10% to 90% of the supply voltage.

Ratiometric pressure sensors are an ideal output type for

• IoT
• Embedded Systems
• Arduino
• Low power systems.

Key rules for Ratiometric pressure sensors are:

•  Output is 10% to 90% of the supply.
• Low Power.
• If the supply Voltage changes the output value will change.

Ratiometric output is becoming increasingly popular and is a common choice to measure pressure with embedded and electronics design engineers.

Ratiometric connections

Ratiometric is a voltage output which requires at least 3 connections these are

• VDD Power 3-5V
• Signal Output
• VSS 0V

Ratiometric Output Span

The voltage span also depends on the supply voltage, for a typical 5V system the span is 4V. The below diagram illustrate the span relationship to the supply voltage.

The span is calculated by the ZeroVoltage - FullScaleVoltage

What is the Voltage output for Ratiometric output.

Keynote to remember the output Voltage is proportional to the Supply Voltage.

Zero pressure – output Voltage 10% of the supply voltage

Midpoint pressure – output Voltage is 50% of the supply voltage

Full scale pressure – output Voltage 90% of the supply voltage

Example of a 5V 0-10 Bar Ratiometric pressure sensor

Supply  = 5V  

Pressure Range = 0-10 Bar

Pressure Span  = 10 Bar

Voltage Output = 10% to 90% of Supply

Voltage Output = 0.5V to 4.5V

Voltage Span = 4.5V-0.5V=4V

How to calculate pressure value from Ratiometric Voltage

To work out the pressure from the Ratiometric output voltage the below formula calculates this

Therefore using and example of 2.5V

Mechanics

OnlineSensors Ltd Ratiometric Pressure sensor is available in the following forms as standard. Customisations are available

M12 Ratiometric Presure sensor

IP65 Cable gland Ratiometric pressure sensor

Conclusion

This simplistic equation and low operation voltage indicates why Ratiometric pressure sensors are a popular choice for embedded systems.

Ratiometric pressure sensors are available from the OnlineSensors Store