Hi Sirs,
Sorry to bother you.
We use ISO1540 and we found the waveform is be inverted from the original waveform
(CH1: I2C_SCL_S0, CH2: I2C_PSE_CLK_IC)
We saw over shoot & under shoot on channel 2
Is it normal?
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Hi Sirs,
Sorry to bother you.
We use ISO1540 and we found the waveform is be inverted from the original waveform
(CH1: I2C_SCL_S0, CH2: I2C_PSE_CLK_IC)
We saw over shoot & under shoot on channel 2
Is it normal?
Hi Shu-Cheng,
Thanks for sharing the waveform and schematic for better understanding of the issue.
I see you have mentioned that the output is inverted from the input signal in your post but I do not see any such inversion in the waveform. I am assuming the inversion is not the issue and the issue is the noise seen on the output waveform. Could you please confirm this?
I am not very sure where this noise is coming from, ISO1540 doesn't produce such noise. It is possible that the power supply +V3.3_PSE is noisy or the PCB layout is not optimum which is leading to noise coupling from other circuit on the same or nighbouring PCB. Please do share +V3.3_PSE waveform and customer PCB layout to check if there is any issue in them.
I also noticed that there are no pull-up resistors listed on I2C_SDA_S0 and I2C_SDA_S0 pins, I am assuming the pull-up resistors are not visible in this schematic but are present in rest of schematic which is not shown here. Thanks.
Regards,
Koteshwar Rao
Hi Shu-Cheng,
Please do share us your inputs or let us know the update on the issue so that we can help you address this issue. Thanks.
Regards,
Koteshwar Rao
Hi Sirs,
The oscilloscope will short the ISO GND to the digital GND
Remove digital GND, ISO1540 waveform is normal
Thanks for your help.