Interfacing AD620 to a PIC microcontroller

Jun 25, 2007 1 Replies

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booth 19 years ago

Dear All, I have a 4-20mA pressure sensor and use a microcontroller to measure the pressure. My region of Interest is 9-11mA and an AD620 maps it to

0-5V. However, occasionally the pressure swings and the output of the AD620 becomes negative or above 5V due to the high gain of the amplifier. I wonder if negative or >5V will hurt the A/D port of the microcontroller. Do I need a clamping circuit that holds the output between 0-5V.

Thanks

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colin 19 years ago

the spec tells you what input is safe, but with most PIC you cant go outsdie the supply voltages by more than a fraction of a diode drop.

cant the ad620 work of 0-5v or use some other chip that does? this will assure limited range.

a resistor and schotky diode clamp to the rails would be suitable clamp otherwise.

Colin =^.^=

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