PhoenixofMT

Member Since: January 13, 2015

Country: United States

  • The load spec refers to the input resistance of the device connected to the output. If you connect it to an ADC pin on a microcontroller, that pin must present a resistance of at least 80k. Same if you connect it to an op amp to buffer/scale the signal. If you wanted to scale it down with a simple voltage divider, the total resistance must be at least 80k. The input resistance of the ADC pins on the Arduino Uno is 200M. The uA741 op amp is 2M. Either can be driven directly from this sensor. The reason for this is that there is an internal resistance in the sensor, probably 1-5k. Assume it's 1k. If you connect a 9k resistor from the output to ground, you will have a voltage divider, and at a full scale output of 5V, you will only measure 4.5V across your resistor. This will throw off your measurements. It will also try to pull 500uA. The datasheet doesn't have an "absolute maximum ratings" section, but 500uA looks like the most it can manage for the whole device, not just the load.

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