Joined: 28 June 2006
Location: US
Posts: 9

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From the MLX90308 & MLX90314 User's Manual: "Voltage mode can be used simultaneously with Current mode."

We are currently using the MLX90314 in our design. We would like to be able to use both voltage mode and current mode at the same time. The user's manual does not clearly indicated how to calibrate the MLX90314 for this type of setup.

I can calibrate in current mode or voltage mode with no problems. (I'm doing either a 1-5V calibration or a 4-20mA calibration). When I try to use both modes simultaneously, though, I see unexpected results.

For example, if I select only current mode, then calibrate my 4mA & 20mA points, when I then select voltage mode (I'm now in simultaneous mode), my 0 and span (i.e. 4 & 20mA) points shift.

Can you please detail how to correctly calibrate for simultaneous voltage/current mode and/or point to documentation that elaborates on this type of calibration?

Joined: 1 January 2005
Location: US
Posts: 43

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Hello,
There are no provisions to calibrate the Voltage and Current modes simultaneously. If you look at the block diagram on the datasheet, the voltage and current outputs are sharing the same calibration circuits.

Joined: 28 June 2006
Location: US
Posts: 9

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I believe I did not state my question clearly. I understand that the calibration circuits are shared between voltage mode and current mode.

My question is how do I use both voltage mode and current mode simultaneously (the datasheet specifically points to this as being a feature)?

As indicated above, if I have only current mode selected and calibrate, when I then use the config software to select voltage mode (with current mode still selected) the current mode performance has changed (even though I did not change any calibration parameters).

This behavior seems unexpected to me.

Can you provide any details as to the proper use of simultaneous voltage and current mode?