>1Mohm impedance on Teensy 3.2 analog inputs?

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clawsoon

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The datasheets for these resistive position sensors say that impedance needs to be >1Mohm for accurate performance:

https://www.murata.com/~/media/webr...alog/products/sensor/rotaryposition/r51e.ashx

https://industrial.panasonic.com/cdbs/www-data/pdf/ARE0000/ARE0000C1.pdf

Do I need to add anything to the connection from position sensor to Teensy 3.2 analog input pin to achieve >1Mohm impedance? Capacitors, resistors, inductors?

If it makes a difference, the wire lengths from position sensor to Teensy will be 5-20cm.

Thanks.
 
What resolution and sample rate or bandwidth do you need? You could simply put a 1M resistor in series, that would make your sensor happy, but the Teensy ADC unhappy (either extremely high noise, and/or slow response with a filter capacitor, due to RC time constant). Normally with such a high impedance requirement you would use an active device, like a buffer opamp between the sensor output and the ADC input.
 
What resolution and sample rate or bandwidth do you need? You could simply put a 1M resistor in series, that would make your sensor happy, but the Teensy ADC unhappy (either extremely high noise, and/or slow response with a filter capacitor, due to RC time constant). Normally with such a high impedance requirement you would use an active device, like a buffer opamp between the sensor output and the ADC input.

Thanks for mentioning opamps. With that hint I found this article which goes into more detail about the tradeoffs involved in driving an MCU ADU with a resistive voltage divider:

https://www.embeddedrelated.com/showarticle/110.php
 
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