ADS1675 performance not so good about 12bit,why the ainn and ainp has a clock noise about 32MHz

Yuelei Tong

Other Parts Discussed in Thread: ADS1675, THS4521

I have done the ADS1675 board,and I got the ADS1675 data.But there's something not so good that the noise is very very big,about 500uV from the ADC,and more,the ainn and ainp has a clock noise,about 7mVpp,32M,is equal to the AD clk. I just want to know why?

over 9 years ago

0 Greg Hupp over 9 years ago

TI__Mastermind 23235 points

Are you using the EVM? If not, please send your schematic.
How is the device configured? What are the signal sources?
- A good test is to short the input pins and see what the noise looks like.

0 He Winston over 9 years ago in reply to Greg Hupp

Prodigy 185 points

Hi
I have the same problem,that the inn and inp has a clock noise 32MHz. When I pull down /PWD pin,the noise disapper.
Can I send you our schmematic?
Thanks!

0 He Winston over 9 years ago

Prodigy 185 points

Have you resolved the problem?

0 Yuelei Tong over 9 years ago in reply to He Winston

Prodigy 30 points

Hi,we both have the same problem,but I don't solve it until now.This only affect the precision performance,I think.Do you have a good precision performance?

0 He Winston over 9 years ago in reply to Yuelei Tong

Prodigy 185 points

I haven't test the performance yet.Which OP do you use?can you send me your schematic?

0 Yuelei Tong over 9 years ago in reply to He Winston

Prodigy 30 points

THS4521,basic sch，5V avdd,2.5V vcom,4 resister I use 1k.I'm now at home,and don't have the sch.Because of BW requirements,I closed all of the filter of ADS1675,and have a bad precision performance.

0 Greg Hupp over 9 years ago in reply to He Winston

TI__Mastermind 23235 points

Hi He -
If the 32MHz is common to both inputs, you should not have a problem since the input signal is a differential signal. You may want to look at you layout and better route your input signals to keep them away from clock and clock noise that may be coupling from your PCB.

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ADS1675 performance not so good about 12bit,why the ainn and ainp has a clock noise about 32MHz