Understanting the icl7107(adc with display)

[saviour84]

Hi guys, I am attempting to understand the 200mV configuration of th icl7107 (fig 1) in the datsheet attached. My question is the analogue ground shorted internally with the power of chip? why is the reference voltage is connected between the 9V supply and the analogue ground?instead connected by the ground of the power supply?Thanks

 

[IRstuff]

Do you think that they would corrupt the analog ground by tying it to the digital ground?

TTFN

FAQ731-376

 

[Skogsgurra]

Answer to your first question: No, IN LO ("analogue ground") is not connected internally to power supply ground. The analogue section of the chip is floating and can accept any differential voltage within the common-mode range of the chip.

From the data sheet: "The input can accept differential voltages anywhere within the common mode range of the input amplifier, or specifically from 0.5V below the positive supply to 1V above the negative supply"

Study the schematic diagram in figure 3. It answers all your questions. There is also explanatory text that is worth studying.

Gunnar Englund

http://www.gke.org

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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

 

[saviour84]

Many thanks for your replay! You mention fig.3 in the datasheet attached.I can't understand in this figure is lamp symbol.Can someone help me and tell me the perpose of this symbol please?Good day and thankyou in advanced.

 

[benta]

Analog switches.
Why don't you just buy a ready-made voltmeter module? There are tons of them out there.

Benta.

 

[IRstuff]

There are no lamps in figure 3

TTFN

FAQ731-376

 

[saviour84]

Sorry, we cant understand each other clearly, its my problem.I am trying to be more clear ,the symbol is marked on the this attachment. Please can you tell me the function of this symbol in this circuit .Thank you for your patient.

 

[IRstuff]

I understood you perfectly. You need to read the datasheet.

TTFN

FAQ731-376

 

[saviour84]

I read the datasheet.I am telling you what I am understood.
There are three state of the symbol ,the Auto Zero,the Integrate State and De Integrate State.The symbol is used as the current flow or as an indication path of the current between each state, I think so. Did I understand well, tell me please.Thanks.

 

[Skogsgurra]

The "lamps" are analogue switches. The text close to the switches tell when they are closed. Sorry, we cannot take you by the hand through this. You need to do some of the work on your own. I think that you are getting close to understanding now.

Gunnar Englund

http://www.gke.org

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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

 

[saviour84]

Many thanks I understand you perfectly, thankyou I understand now.Good day all the best!