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Should UCD9240 be programmed befor functoining?

Xiang Chao
Intellectual 360 points
Other Parts Discussed in Thread: UCD9240, UCD9248, UCD9246

I am considering using UCD9240 as power manager.

There are something I want to figure out.

1. Is there a default configuration stored in it? Or I should program it before it can output PWM signal?

2. Can I program it with a common MCU with I2C interface?

Thanks.

  • 0
    TI__Intellectual 1755 points

    Xiang Chao,
    The UCD9240 has 4 error amplifier inputs and 6 or 8 PWM outputs.  Before it is configured, the PWM outputs are not assigned to an input and are disabled.  Therefore, you need to configure the device to identify which inputs are assigned to a voltage rail and which PWM outputs will drive that voltage rail.  The PMBus command that makes this assignment is called PHASE_INFO.  You will also need to set the regulation voltage, and the over/under fault thresholds for voltage, current and temperature for each voltage rail. 

    Yes, you can configure the UCD92xx controller over the I2C based PMBus from a MCU, as long as the I2C interface supports clock stretching as defined for SMBus and PMBus.  (This is where the slave device is allowed to hold the clock low while it determines whether to ACK or NACK the command.)  Configuration is most easily done through the TI Fusion Digital Power Designer.  I would recommend the following design sequence:
    1.  Use the Fusion Digital Power Designer to create a design for the MOSFET power stages that drive each voltage rail.  Save the design schematic, output voltages, fault limits and compensation coefficients in a configuration project file. 
    2.  From the above configuration, create the board design for your system.  Include a header or testpoints for the PMBus so that the TI UCB2GPIO adapter can be used by the Fusion design tool to assist in bringing up the first board.  Layout, fab and assemble your board. 
    3.  Apply power to the first assembled board and download the project file over the PMBus with the UCD2GPIO adapter and Fusion design tool.  Make any necessary adjustments to the configuration. (For instance, you may want to fine tune the current sense gain and offset used to monitor current.) 
    4.  Now that you know that you can correctly bring up the power system on your board, use the Fusion design tool to export a script of the PMBus configuration commands needed to program the device.  (File/Export)
    5.  From the script, create the sequence of PMBus commands that the MCU will issue to configure the power for the rest of the boards you plan to produce.

    Note that the UCD9246 and UCD9248 are newer versions of the UCD9240 that have improved sequencing capability. 

     

     

  • 0 in reply to Mark Hagen
    Intellectual 360 points

    Thank you for your response.
    With the file exported by Fusion design tool, the UCD9240 only need to be programmed once by a MCU. Is that right?

    Thanks.

    Xiang Chao

  • 0 in reply to Xiang Chao
    TI__Intellectual 1755 points

    That is correct.  The configuration process, as defined in the PMBus Standard, is to first write all the configuration registers in the device.  Then send the STORE_DEFAULT_ALL command to save those register values to nonvolatile memory (flash).  On subsequent applications of power, the controller will use the saved configuration values.