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Problem Description:
After the temperature of the thermal imager test chip rises by 50 degrees, the input is 0, and the output has noise and serious interference. The output waveform is shown in the attached picture. After the temperature decreases, the output noise disappears and the output waveform is particularly clean. Please help analyze.
PCB Description:
The analog ground and digital ground of the circuit board are not grounded at a single point. The two grounds are shared. See the attachment for the schematic diagram and some PCB pictures. If there are any good suggestions for PCB layout, you can also provide the following information. thank you!
User,
Place the ADC in ramp test pattern mode and see if the output gets corrupted at hot temperature. If not, I would guess the issue is with the analog front end.
If the output gets corrupt, try slowing down the sample rate to see if this fixes the issue. If this does help, there is probably a timing issue. Use registers 0x04, and 0x0E to adjust clock and data timing as well as drive strength.
Attached are PCB layout tips and guidelines for your reference.
Regards,
Jim
5811.High Speed Serial Link Layout Recommendations.pptx8267.CMOS Schematic and Layout tips.ppt