Continue to Site

Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

Register Log in

How to get 12 bits precision with BurrBrown A/D?

Status
Not open for further replies.
2

2000

Member level 5
Joined
May 14, 2001
Messages
87
Helped
0
Reputation
0
Reaction score
0
Trophy points
1,286
Activity points
764
hello friends,

Once more I need your help, I'm working with a BurrBrown A/D ADS7812 12bits, bipolar, +5V single supply. I'm having problems with its precision, I'm unable to get the 12 bits precision, actually I'm really far from them. Anybody have already worked with thease A/D's?
Any help is welcome.

regards,

2000
 

Attachments

  • DSC06273.JPG
    DSC06273.JPG
    3.5 MB · Views: 165
  • DSC06264.JPG
    DSC06264.JPG
    3.5 MB · Views: 166
  • DSC06266.JPG
    DSC06266.JPG
    3.6 MB · Views: 160
  • DSC06269.JPG
    DSC06269.JPG
    3.5 MB · Views: 160
  • DSC06280.JPG
    DSC06280.JPG
    3.5 MB · Views: 161
  • DSC06279.JPG
    DSC06279.JPG
    3.5 MB · Views: 164
  • DSC06278.JPG
    DSC06278.JPG
    3.5 MB · Views: 182
  • DSC06277.JPG
    DSC06277.JPG
    3.5 MB · Views: 176
  • DSC06274.JPG
    DSC06274.JPG
    3.5 MB · Views: 175
  • DSC06272.JPG
    DSC06272.JPG
    3.5 MB · Views: 147

hi
you should add low pass (LC) filter on analog power line.
thx
 

pot a low pass filter too, to AD input, and check the REFERENCE!!!! is designed for 12 bits???? if n -> NO WAY... :smile:
check your PCB and remove the earth current loop, and use guarding architecture...
i miss something? (is much possible...:smile:)

best,
//a
 

HI friends,

Thanks for the help, the board I'm using is almos the one used for the test board distributed by BurrBrown... the decoupling capacitors, the ground plane, everything... but the precision is poor...
Do you sugest any other A/D like the one I'm using, I mean,12 bits, 200KHz sample, bipolar, serial, single supply, +-3V or +-5V scale??? I'm having difficulties to buy the ADS7812P and I'd like to choose one that would be cheap and easy to find, any sugestions?


2000
 

what test(s) did you do to determine this? have you looked at input to adc with an o-scope?
 

...but ADS7812 work great... anyway if yo want to simplify your design you could use some interesting AD from cr*ystal sem*iconductor ( a division of cirr*us-lo*gic)
best,
//a
 

sure,

I've put a known DC at its input and whatched it with an osciloscope... it is pure stable DC but the A/D varies its 3 last bits... I've used the decoupling capacitors but it still drifts...

2000
 

check the reference circuit this AD workz ok!!
 

check you power supply. this usually happens when your ps out put is not clean. you have to add inductor in analog supply input in addition to decoupling caps.
thx
 

Have you checked the
serial clock feedtrough ?

chief451
 

Status
Not open for further replies.

Similar threads

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Back
Top