LT1790 Voltage Reference

Sal Ammoniac

Has anyone used this Linear Technology voltage reference? I got two of the 4.096v (LT1790-4096) parts as samples with the intention of using them as Vref for my 12-bit ADC so the transfer function would be 1mV per step.

The input voltage range on these parts goes up to 18v and the dropout voltage is only 50-100mV. I connected these up as shown in the datasheet with a 9v Vin and measured the no-load output on Vout. On both parts I see ~0.335 volts on the output. I was expecting to see 4.096v.

Am I doing something wrong?

sam_sam_sam

Did you put the two·0.1 uf·caps the ones··on the input and output on the regulator and are other end of the caps tied· to ground ·and are·pins 1 and 2 to to ground very importance that this is done or you will get these weird reading that you are getting


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··Thanks for any··that you may have and all of your time finding them

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Sam

Post Edited (sam_sam_sam) : 12/6/2009 3:03:01 AM GMT

Sal Ammoniac

Yep, pins 1&2 are tied together and both input and outputs have 100nF caps.

kwinn

Are pins 3 and 6 floating. The spec sheet says do not connect.

Sal Ammoniac

Found the problem. When I looked at the connections with a 10x loupe, I noticed that the 100nF cap on the Vout pin wasn't making contact with ground. I fixed that and now see 4.096v on the output.

Man, those tiny surface mount components are brutal on my 50 year old eyes.

Franklin

I'm seriously thinking of getting a usb microscope sometime soon to keep my face out of the solder fumes.

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- Stephen