ISO224: output noise

Yasushi Fujiwara

Part Number: ISO224

Hello Experts,

My customer is evaluating ISO224B and found output noise. He tied input to GND1 and monitor the OUTP/N. Please see attached file. Does it internal oscillator noise?

https://tidrive.itg.ti.com/a/MqA7KL6gOz4goDsy/27a536c7-75e3-4f2e-bae0-7558b5d57804?l

Best Regards,
Fujiwara

over 3 years ago

0 Alexander Smith over 3 years ago

TI__Mastermind 47595 points

Hi Fujiwara-san,

Yes, this appears to be internal oscillator noise. When the customer does a differential measurement at the ADC or differential to single-ended conversion, much of this noise should be cancelled out.

0 Yasushi Fujiwara over 3 years ago in reply to Alexander Smith

TI__Genius 11695 points

Hi Alexander,

Thank you for answer. Would you please provide an oscilloscope shot of this noise waveform of EVM? Customer would like to get it for a reference.

Best Regards,
Fujiwara

0 Alexander Smith over 3 years ago in reply to Yasushi Fujiwara

TI__Mastermind 47595 points

Hi Fujiwara-san,

Please do not spam the forum with repeated questions.

If you search the forum, you will find that this is a well documented question customers have. This noise on the output is normal and is why we recommend low-pass filtering and differential measurements at the ADC, or a proper differential to single-ended conversion when interfacing with a single-ended ADC.

https://e2e.ti.com/support/amplifiers/f/amplifiers-forum/958086/iso224-550khz-noise

Furthermore, if you look at "Output noise" in the electrical characteristics table in the datasheet, you will see that the output noise is only specified with a bandwidth of 100kHz. The noise shown in the attachment is beyond the specified bandwidth.

+1 Alexander Smith over 3 years ago in reply to Alexander Smith

TI__Mastermind 47595 points

Hi Fujiwara-san,

Please see attached.

Amplifiers

Amplifiers forum

ISO224: output noise