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TPS544B25: Same PMBUS for 3 x TPS544B25

Shlomi Yehezkia
Mastermind 6150 points
Part Number: TPS544B25

HI Team,

1) In schematics of a new card I want to use 3 x TPS544B25 (AVS).

Can I add only 1 x PMBUS Connector for 3 x TPS544B25?

I want to control separately each one.

2) Attached the EVM schematics of TPS544B25.

For setting the TPS544B25 to 0.72V without using the PMBUS, which resistor should I change?

Is the CNTL (pin 1) , like ENABLE pin?

Thanks,

Shlomi 

 

TPS544B25.docx

  • 0
    TI__Guru**** 191445 points

    Shlomi,

    1. Yes you can use one PMBus header.  Make sure each TPS544B25 has a unique address set via the ADDR0 and ADDR1 pins.

    2.  The default value programmed for Vout is 0.95 V.  To get a lower voltage, you will need to do some programming.  You can set it once for 0.72 and store that as the default in eeprom.  Going forward, it will power up to 0.72 without any other interaction.  For Vout less than 1 V, you will need to VOUT_SCALE_LOOP set to 1.  In that mode, no lower resistor is required.

    3.  Yes the CNTL pin acts like EN in the default configuration.  You can change that from the PMBus.

  • 0 in reply to JohnTucker
    Mastermind 6150 points

    Hi John,

    Ok, for the CNTL question #3.

    For the second question, without using the PMBUS, how can I change the 0.95 to be 0.72v?

    (I cannot give the load 0.95V at start up – it is 30% more than the nominal 0.72v)

    Thanks, 

    Shlomi

     

  • 0 in reply to Shlomi Yehezkia
    TI__Guru**** 191445 points

    Shlomi,

    You should set up the TPS544B25 prior to attaching the load a single time.  You can store the new settings in eeprom as the new defaults.  Then you can power up to 0.72 V automatically without further PMBus commands.

  • 0 in reply to JohnTucker
    Mastermind 6150 points

    Hi John,

    If all PMBUS pins are floating in schematics (no PMBUS supported in card) , how should I set the output to 0.72v?

    Thanks,

    Shlomi

     

  • 0 in reply to Shlomi Yehezkia
    TI__Guru**** 191445 points

    Shlomi,

    The default value for Vout is 0.95 V.  You can set a higher output voltage by using a divider circuit.  To get a lower voltage you have to change the VOUT_COMMAND value.  If you do not have PMBus support on your card, it begs the question "Why are you using TPS544B25 instead of a non-PMBus device?".  You could conceivably pre-program the TPS544B25 prior to assembly.  There is possibly a work around if you can inject current into the FB node.  Is one of those an option for you?  Can you tell me details about your application?  I may be able to suggest a suitable alternative.