LTC6820 timing issue

Hi ADIexpert

my customer found some timing mismatch of  t16 (CS Falling Edge to isoSPI Data Transmit)  and t14 (SCK Non-Latch Edge to isoSPI Data Transmit) from the datasheet of LTC6820

below test results are tested at slave side , the setting of the SPI mode is 1 (POL=0, PHA=1), Slow=0 (SPI CLK = 750kHZ)

Also ,it used Capacitive Isolation Barrier for the  ISO SPI but not transformer (the cable length is under 1m)

please see the waveforms below:

1. Purple waveform is the ISO SPI (IP-IM)   yellow waveform is the CS

the timing is 8.43us , which fail the t16 spec (<345ns)

 

 

2.Purple waveform is the ISO SPI (IP-IM)   yellow waveform is the CLK

the timing is 930ns, which  Fail the t14 spec (<190ns)

May I have some of your suggestion if the test or the setting was wrong?

thanks

Ken



Add some highlights for the key setting
[edited by: Kencheng at 3:30 PM (GMT 0) on 6 Oct 2019]