AMC1305M05: Sinc3_16 and ripple wave relation ship

user4370495

Part Number: AMC1305M05

Dear E2E:

I Use AMC1305M05 as a sense currents in green energy system.

In no load conditon: sample rate: sinc3-16 the ripple wave about channel 1 was a little high, but the channel 2 is normal;

But i change the sample rate: sinc3-32 the ripple wave reduce quickly and the channel 2 still is normal;

i have double check the GND & VDD net is fine, the schematic are the same. so i was little confused what's the reason?
i also do load condition , the situation is same.
sinc3-16: channel 1 is bad; channel 2 is fine;
sinc3-32: channel 1 is fine; channel 2 is fine;

schematic:

over 5 years ago

0 Alexander Smith over 5 years ago

TI__Mastermind 47595 points

Hello,

Thanks for your post!

When you say channel 1, do you mean MDAT06 and channel 2 is MDAT07?

This could be a result of an offset in your nets (IA1, IB1, glA, glB) or perhaps channel 1 is closer to a noise source that is susceptible at sinc3-16 sampling rate.

Can you provide additional schematics showing these nets as well as the channels location on the board?

0 user4370495 over 5 years ago in reply to Alexander Smith

Expert 1155 points

Dear Alexander:

thanks
Schematic 1:

Load circuit:

ISO Power:

Circuit Measurement :

第六版APF_IGBT板V21_英飞凌.pdf

And i have double check the PCB layout about A-Channel and B-channel. the different is the position of resistor R1 & R2,
and so the via in A-channel near C31/C41.
Thanks

A channel:

B channel:

0 Alexander Smith over 5 years ago in reply to user4370495

TI__Mastermind 47595 points

Hello,

Thank you very much for the detailed schematics and layout.

I think this is noise coming from R1 and going directly to the device. I would suggest moving R1 above C41 and C31 such that the trace must pass through the capacitors before going to the device.

On channel 2, the resistor R2 connects to the capacitors (C42, C32) before going to the device.
On channel 1, the resistor connects directly to the device in one direction, and the capacitors in the other.

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AMC1305M05: Sinc3_16 and ripple wave relation ship