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edhaslam
Joined: 15 Jul 2005
Posts: 89
Location: UK
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| Can anyone recommend the MCP3425 ADC? |
 Posted: Fri Jun 13, 2008 3:55 am |
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Just wondered if anyone had come accross this ADC from Microchip and if it was any good (or had any issues with it!)?
I have an application where I am measuring 8 channels of DC voltage i.e. speed is not an issue, and need separate 16-bit ADCs to carry out the conversion. Low noise (<2uV) would also be a considerstion.
My only concern with these chips is that the address seems to be hardcoded into them, so having multiply chips could be a problem? Can anyone recommend another device? |
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Steve H.
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| Posted: Fri Jun 13, 2008 9:36 am |
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You might get more help on the Microchip forums - they seem pretty lively.
I have no experience with this part, but there are plenty of dual channel ADC's in the world. TI makes many - this would save a chip and allow one driver / pin set to drive the device.
Consider looking at SPI devices - there are more of these than I2C to choose from.
HTH - Steve H. |
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treitmey
Joined: 23 Jan 2004
Posts: 1094
Location: Appleton,WI USA
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| Posted: Fri Jun 13, 2008 11:24 am |
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| or if slow enough, a analog mux and the A2D that is on the chip. |
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edhaslam
Joined: 15 Jul 2005
Posts: 89
Location: UK
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| Posted: Mon Jun 16, 2008 1:26 am |
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Thanks for the comments guys.
| treitmey wrote: | | or if slow enough, a analog mux and the A2D that is on the chip. |
I think I'll go down the analogue mux route and pick a really good 16-bit ADC (low noise). Switching speed shouldn't be too much of a problem, so this solution could work out really well. I'll probably use somthing like this:
http://www.analog.com/UploadedFiles/Data_Sheets/ADG526A_527A.pdf
That way I can use the PIC to control the mux. With it being a 16-bit mux I can add the option of having more channels in the future.
Is there anything to watch out for when using an analogue mux? Will they introduce a lot of noise? |
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treitmey
Joined: 23 Jan 2004
Posts: 1094
Location: Appleton,WI USA
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| Posted: Mon Jun 16, 2008 11:42 am |
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Sorry, but I've never used that chip.
I guess I would say try it and see.
Sorry that this wasn't much help.
Can anyone comment on this or any other Analog mux? |
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edhaslam
Joined: 15 Jul 2005
Posts: 89
Location: UK
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| Posted: Tue Jun 17, 2008 1:33 am |
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| treitmey wrote: | Sorry, but I've never used that chip.
I guess I would say try it and see.
Sorry that this wasn't much help.
Can anyone comment on this or any other Analog mux? |
No problem!
The only problem I can see so far is that the Ron resistance of this chip is around 280 ohms, which is too high for my application. However, they do an ADG706 which has an Ron value of around 2 ohms. Much better!
As you say, probably the best thing to do is to prototype it and see what problems are caused. |
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