Interfacing AD620 to a PIC microcontroller

[booth]

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

 

[colin]

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

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 =^.^=