XTR115 to convert single variable resistance parameter

John Es

Other Parts Discussed in Thread: XTR115

I'd like to hear from anybody familiar with XTR115 or XTR116 on their recommendations how to convert 0-1000 Ohm linear resistance to 4-20mA...

Any circuit ideas or schematic examples other than going full bridge front end?

John

over 14 years ago

0 Art Kay over 14 years ago

TI__Mastermind 22297 points

You should consider an XTR114. It was developed for a 1000 ohm RTD, so it fits your application well. RTD’s have nonlinearity, so the XTR115 has the ability to correct for the nonlinearity. You don’t need to use this so do not include Rlin (leave it open).

Also short out Rz (i.e. Rz =0 ohms). You don’t need Rz because your resistance range starts at zero.

Also Rg = 2.5k ohm for to give a 20mA output on a 1k ohm resistance. See calculation below.

0 John Es over 14 years ago in reply to Art Kay

Prodigy 100 points

How can I change a XTR115 2.5V voltage source into a practical 100uA current source?

0 Ian Williams over 14 years ago in reply to John Es

TI__Mastermind 27715 points

John,

I'm closing this thread since you found an answer to your current source question in this thread: http://e2e.ti.com/support/amplifiers/precision_amplifiers/f/14/t/75602.aspx

Best regards,
Ian Williams

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XTR115 to convert single variable resistance parameter