Voltage Divider

The circuit below shows a voltage divider (RSEN and R3) that converts the sensor resistance to a voltage. The MCP6XXX op amp acts as a voltage follower (buffer). If the op amp and resistors are ideal then VOUT = (VDD) R3/(RSEN + R3).

voltage-divider.png

Advantages:

  • Simplicity
  • Ratiometric output (with Analog-to-Digital Converter (ADC) using VDD as its reference voltage)
  • Detection of open sensor due to failure

Disadvantages:

  • Poor common mode noise rejection
  • Voltage is non-linear with resistance

Sensor Examples:

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