Author Topic: Instrument Amplifier gets Warm  (Read 2255 times)

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Offline PStevensonTopic starter

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Instrument Amplifier gets Warm
« on: October 26, 2011, 09:15:12 pm »

I made a microphone preamp using a INA217 Instrument Amplifier IC at the heart of it and to power the overall circuit I used an LT1054 switch cap voltage converter to give me upto -15/+15 voltage, the whole circuit works fine however I am very new to using Instrument amplifier IC's and when this circuit is running it gets warm - not too hot to touch or anything just noticeably warm I just want to know if this is normal really.
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Offline amspire

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Re: Instrument Amplifier gets Warm
« Reply #1 on: October 26, 2011, 10:32:45 pm »
You are running at +-15V with a 10mA quiescent current, so that is 300mW in the amp - you should feel it as a little warm.

Richard
 

Offline PStevensonTopic starter

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Re: Instrument Amplifier gets Warm
« Reply #2 on: October 26, 2011, 11:01:40 pm »

thankyou, so it won't damage the IC or shorten its life at all?
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Offline amspire

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Re: Instrument Amplifier gets Warm
« Reply #3 on: October 27, 2011, 12:27:04 am »
No. It is exactly the way that that particular IC works.

You can get much lower power IC's, but that is probably a pretty nice chip, if you don't mind the 300mW.

Richard.
 

Offline PStevensonTopic starter

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Re: Instrument Amplifier gets Warm
« Reply #4 on: October 27, 2011, 09:58:57 am »

no, I don't mind the 300mW - I should have probably read the datasheet a bit more closely I was shocked when I plugged in the old DMM and saw the power usage but it's not a problem - it'll be mains powered

thanks so much for the info
I learned more from the EEVBlog than I did in school
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