What happens if the system draws more than advertised?

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MiMu_4671456
Level 1
Level 1

I'm planning on building a setup using the BCR IC. What will happen if the BCR advertises 12V/3A to a compatible source but later the system starts drawing 5A?

Will the BCR detect this and terminate the connection and revert back to 5V or is it solely the responsibility of the system designer to limit the system such that the advertisement is correct?

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1 Solution

Hi ,

The process is below:

1) The SOURCE have capabilities to 20V/5A, but attached BCR controlled device with a non-EMCA cable. The Source will only advertise 20V/3A.

2) And BCR have capabilities to sink 20V/5A. But the source just advertise 20V/3A. The BCR will request 20V/3A with cap_mismatch bit set 1.

3) And then, the Fault of BCR is enabled.

4) And then, Turn off SINK FET and Trun on SAFE_PWR_FET. And go to 5V on VBUS.

Best Regards,

Lisa

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3 Replies
ShifangZ_26
Moderator
Moderator
Moderator
10 likes given 250 sign-ins 1000 replies posted

Hi ,

What's you describe is the VBUS over current case. You are correct that it is solely the responsibility of the system designer to limit the system current. The BCR do not terminate the connect at this condition. But the Source will be terminate the connect if the VBUS over current is occurred.

Best Regards,

Lisa

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MiMu_4671456
Level 1
Level 1

Hi Lisa,

thank you very much. So analogous if I ask for 20V/5A from a compatible source and use a non-EMCA cable the source will only supply 5V/1A, correct?

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Hi ,

The process is below:

1) The SOURCE have capabilities to 20V/5A, but attached BCR controlled device with a non-EMCA cable. The Source will only advertise 20V/3A.

2) And BCR have capabilities to sink 20V/5A. But the source just advertise 20V/3A. The BCR will request 20V/3A with cap_mismatch bit set 1.

3) And then, the Fault of BCR is enabled.

4) And then, Turn off SINK FET and Trun on SAFE_PWR_FET. And go to 5V on VBUS.

Best Regards,

Lisa

0 Likes