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UCD9222 problem on C6678 board

haopeng han
Expert 1120 points
Other Parts Discussed in Thread: UCD9222, UCD7242

Hi,

I'm now debugging our C6678 board. We use UCD9222 & UCD7242 for DSP core power supply. Our design is almost the same with the EVM, so we use the same configuration file as the EVM.

Now we are able to download the configuration to UCD9222 through the USB-TO-GPIO tool. But it does not work. The PWM outputs of UCD9222 stay low. (I did the same download  process on the EVM, and that's OK. )

So I wander did I miss something? What key points should I consider when debugging the UCD9222?  Attached our schematic.(We only soldered the power section of our board for debug)

Any help / suggestion would be greatly appreciated!

Han

7245.power_ucd.pdf

  • 0
    TI__Mastermind 42545 points

    Hi Han,

    The UCD9222/UCD7242 can be effected by a number of issues including layout and component selection.  You stated that you copied the EVM and I didn't see anything in your schematic that looked incorrect.  Did you follow the layout from the EVM as well?  Did you follow all of the layout guidelines described in the UCD data sheets?  Are the UCD1_EN1, UCD1_EN2 and UCD1_CTL signals all high?  You mentioned that you have the fusion software connected.  Is it giving you any warnings?  The ground connections are particularly important around the UCD7242 so check those carefully.

    Bill

  • 0 in reply to Bill Taboada
    Expert 1120 points

    Hi Bill,

    Thanks for your reply!

    UCD1_EN1, UCD1_EN2 and UCD1_CTL are all high. I think we followed the layout rules. 

    The biggest difference between our design and the EVM is:  we switched the connections between UCD9222 and UCD7242, i.e. we connect output channel A of UCD9222 to power stage B of UCD7242.  Can we use the EVM configuration file for this hardware connection? Another thing is we did not solder the DSP, is that OK?

    Attached screen shot of the Fusion Digital Power Designer: monitor.png, the PWM output waveform of UCD9222: tek.png, and the layout of UCD9222 & UCD7242.

    Han

    4048.png.rar

  • 0 in reply to haopeng han
    TI__Mastermind 42545 points

    Hi Han,

    Did you use the exact same components (inductors, capacitor, resistors, etc) in your design or did you substitute other components? If you did not use the exact part numbers from the EVM then you will need to edit the information using the fusion software.  Under the Design tab you fill find a button labeled "Edit Full Power Stage in Schematic".  When you click on that it will present you with a schematic equivalent of the power supply circuit.  Each of the components shown needs to be updated with the specification for the component that you are using.  Click on the value for a component and you will be presented with a window which will allow you to either select commonly used components or to edit the component with the values from your data sheet.  You will need to do this for all the components in your schematic.  We'll need that information to help debug your problem.

    Regards, Bill

  • 0 in reply to Bill Taboada
    Expert 1120 points

    Hi Bill

    The problem is solved now. Turns out the chips we used at first were purchased from the market two months ago. And these chips probably are fake.

    Today we substitute the old chips with new samples, they work just fine.

    Thanks for your help!

    Han