ISO1050: pulse distortion on cable of CANH-CANL

Howard Zou

Part Number: ISO1050

Hi,

my customer uses ISO1050 and the schematic is as below:

they connect two board together to test the communication and find it not working correctly.

So we monitored the CANH-CANL signal on the two board with differential probe and we will observe that there will be very short low pulse circled in red. The voltage supply is stable. We wonder how can we find the cause of such pulse?

over 5 years ago

0 Howard Zou over 5 years ago

TI__Genius 12365 points

We measured CANH and CANL, the waveforms are as below:

are there any way to filter out the voltage dip?

0 Lucas Schulte9 over 5 years ago in reply to Howard Zou

TI__Expert 6955 points

Howard,

Is the customer able to get waveforms of TX, RX, CANH, and CANL all on the same scope shot? How many devices are on the CAN bus? The spikes look evenly spaced which seems to suggest something on the CAN bus might be causing this.

Respectfully,

Lucas

0 Howard Zou over 5 years ago in reply to Lucas Schulte9

TI__Genius 12365 points

Lucas,

we add some capacitor between CANH to GND and CANL to GND. And the problem solved.

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ISO1050: pulse distortion on cable of CANH-CANL