TPS2546: VBUS discharge during mode change

Antony Lin

Part Number: TPS2546

Hi,

I understand that there's a design in TPS2546 to discharge VBUS during mode change as a notification to the device for re-acquisition the updated status. THe question is, does it happens at all mode transition, or just some of the mode transition? Can you list all the mode transition that we could see such VBUS discharge behavior on TPS2546?

Thanks!

Antony

over 7 years ago

0 Chuck Branch over 7 years ago

TI__Mastermind 33171 points

Antony,

Here is the control state machine:

Note that the only transitions that do not cause an output discharge are between CDP (1111) and SDP2 (1110) All other changes result in an output discharge.

Regards,

Chuck

0 Jim CHEN over 7 years ago in reply to Chuck Branch

TI__Expert 4795 points

Hi Chuck,

How about those modes in DCP auto?

We can see there is a transition when the mode change from divider 1 to divider 2.

But there is no transition when the mode change from divider 2 to divider 1.

Do you know the reason?

0 Chuck Branch over 7 years ago in reply to Jim CHEN

TI__Mastermind 33171 points

The DCP state machine that controls DCP auto mode will discharge the bus when it is necessary to support BC 1.2 and non compliant devices.

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TPS2546: VBUS discharge during mode change