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TPS544B25: Questions of TPS544B25

Jimmy Lai
Expert 6845 points
Part Number: TPS544B25
Other Parts Discussed in Thread: TPS546B24A, , TPS546C23, TPS543B20

Dear Team,

I would like to ask, the initial chip is applied by pulling down VSET, whether the default values inside the chip, such as undervoltage and overvoltage, will affect my normal use of the output voltage?

I use VSET to connect the resistance to ground, adjust the upper and lower resistance of FB to output my 2.57V,
My question is if the initial chip has default values such as Vmax Vmin output or undervoltage, will these values affect the normal operation of my chip.

Many  Thanks

Jimmy

  • 0
    TI__Mastermind 30990 points

    Hello Jimmy, 

    I am trying to understand your question before I answer.

    Can you please clarify the question? 

    Thanks! 

    Tahar

  • 0 in reply to Tahar Allag
    TI__Expert 6845 points

    Hi Tahar,

    What I mean is an initial chip, whether there are default values such as VOUTmax VOUTmin VOCP inside the chip, if any:
    My output voltage is connected to AGND through VSET through a resistor, and the upper and lower resistance of FB is changed to achieve an output voltage of 2.57V. Will the default values of these chips affect the normal output of 2.57V? (If my output voltage is not within the range of the default value of the chip)

    Many Thanks,

    Jimmy

  • 0
    TI__Guru 53495 points

     

    Unfortunately the answer is yes, you will have other issues that interfere with the operation of the converter.  The TPS544x25 family of devices monitor the DIFFO pin for sensing VOUT_OV and VOUT_UV warning and fault levels.  Setting the FB reference voltage with the VSET pin and then using a resistor divider from DIFFO to FB to set the output voltage to 2.57V without programming the PMBus command values will trigger an OV fault when DIFFO reaches 1.2V.

    Possible options:

    1) Add a low impedance divider in front of the remote sense amplifier to reduce the voltage at DIFFO to the reference voltage programmed at VSET.  The divider needs to be low impedance due to the input impedance of the remote sense amplifier, which is about 60kΩ with +/- 30% tolerance.

    This will affect the scaling of setting or reading the Output Voltage over PMBus, which sets and senses the voltage at the DIFFO pin.

    2) Use a 10k + 10k 2:1 resistor divider from DIFFO to FB and program VOUT_SCALE_LOOP, VOUT_MAX, VOUT_OV_FAULT_LIMIT, VOUT_OV_WARN_LIMIT, VOUT_COMMAND, VOUT_UV_WARN_LIMIT, VOUT_UV_FAULT_LIMIT and VOUT_MIN in that order over PMBus prior to starting the output voltage.

    3) Select an alternative device, such as the TPS546B24A, which offers all of the PMBus features of the TPS544B25, and allows the Output Voltage to be programmed through the VSEL pin.  While 2.57 is not an available voltage, 2.56 or 2.60 are pin programmable, and the voltage could be set closer to 2.57V via PMBus once the TPS546B24A has powered up.  After the first power-up, this updated VOUT_COMMAND value could be stored to NVM and the Pin Detect Override set to boot to the NVM stored VOUT_COMMAND rather than the pin-programed VOUT_COMMNAD in order to eliminate the need to program VOUT_COMMAND each time.

    4) Depending on your PMBus command needs, you may also be able to select the TPS546C23, which detects VOUT_OV and VOUT_UV warning and faults form the FB pin and does support Output Voltage setting via the feedback divider without PMBus programming.

    5) If you don't need PMBus programming, you could consider the TPS543B20, which also supports VOUT programming with feedback resistors, but does not support PMBus.

  • 0 in reply to Peter James Miller
    TI__Expert 6845 points

    Hi Peter,

    Thanks for your great support!!

    We hope to set it through the PMBUS method, which is your second suggestion. Could you help us gen a code.
    Requirements: Vin:12V vout=2.57V , Itdc=6.6A , Imax=8.9A. IOCP is set to 12A,
    Do we need to provide any information to gen this code? Thanks a lot!

    Many Thanks,

    Jimmy

  • +1 in reply to Jimmy Lai
    TI__Guru 53495 points

     

    If you are looking for a programming script for configuring the TPS544B25 for a specific application, I would recommend using the FUSION Digital Power Designer in Off-line mode.  This graphical user interface will allow you to select the TPS544B25 and the PMBus address you plan to use with it (It will be programmed via the ADDR0 and ADDR1 pins to a value between 0-63d (0-3Fh)

    Once in the GUI, you can Create new Offline system from start 

    Select a device from the GUI support list -> TPS40xxx/TPS53xxx/TPS544xxx/TPS546xxx Analog Power Converters, then pin the TPS544B25 from the list.

    The default address is 36d (24h) but you can select another value, that you will program into the device through the resistors on the ADDR0 and ADDR1 pins.

    Then click "Finish" to create the system.  In the system view, click "Click to configure device" at the right side to open the configuration page for the TPS544B25

    It will open up a new window, allowing you to program the device.

    Go to the "ALL CONFIG" tab at the  upper right side and change VOUT_SCALE_LOOP from 1.00 to 0.50 (0xF002)

    This will put the part into 1.5V - 3.0V operating mode, expecting a 2:1 divider from DIFFO to FB. (Rfb_hs = Rfb_ls) 

    Click "Write to Hardware" on the upper left side to save that change.

    At this point, go back to Limits & On/Off to make setting the current limit and ouptut voltage easier.  You'll need to raise each of the following values:

    VOUT_MAX - Recommend setting to 1.25x VOUT (3.215 - 0x066D)

    VOUT_OV_FAULT_LIMIT - Recommend setting to 1.2x VOUT (3.084 - 0x062B)

    VOUT_OV_WARN_LIMIT - Recommend setting to 1.1x VOUT (2.955 - 0x05E9)

    VOUT_COMMAND - 2.57V (0x0524)

    VOUT_UV_WARN_LIMIT - Recommend 0.85x VOUT (2.185 - 0x045E)

    VOUT_UV_FAULT_LIMIT - Recommend 0.80x VOUT (2.056 - 0x041D)

    MFR_VOUT_MIN - Recommend 0.75x VOUT (1.927V - 0x03DB) 

    With a 9A application current, I would recommend a little more margin than a 12A current limit.  Instead, I would recommend setting:

    IOUT_OC_WARN_LIMIT to 12A (0xF818)

    IOUT_OC_FAULT_LIMIT to 13A (0xF81A)

    this will reduce the risk of false triggering of the OCP level.

    Click "Write to Hardware at the upper left corner again" 

    You you can save the project with File -> Save Project As"  and you can generate a programming script using the File -> Export 

  • +1 in reply to Peter James Miller
    TI__Expert 6845 points

    Hi Miller,

    We appreciated your strong support always! Slight smile

    Have a nice day!

    Many Thanks,

    Jimmy