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TPS55340: Helpful use of sync Pin for multiple boost converters

Part Number: TPS55340

Hi all.

For a mixed signal device (analog part and digital part) I need to have multiple rails in order to make the device function properly.
I need in order:
-36V and +36V for analog output circuit (max current 500mA)
-24V +12V for the DAC part (100mA)
5V references, 3.3V reference, 2.5V reference. (for the DAC and digital part MCU, TFT display)
The goal is to power the device from12V mains transformer.

Now I have in mind using Webench to implement it with multiple IC in various configuration.

At least TPS55340 for the 36 and 24V rail, LM25776 for the -12V rail an so on.

I mean where is the issue on using on the same board different IC's in different topology?

Is there any helpful use of the SYNC pin?

Any help very appreciated as useful.

Best regards.


  • HI Stefano,

    thank you for using the E2E forum.

    There is no issue with having multiple SMPS on one application. This is even used quite often.

    On the layout side you should take care to place them properly so that you do not have an interference between the different SMPS.

    If you need multiple outputs and could tolerate a certain amount of output variation, esp. over load conditions you might also consider an Flyback as this is able to provide multiple outputs with one SMPS (even with negative voltages).

    Best regards,


  • Thank You so much Stefano.

    The device is used for medical application, and therefore the main goal is to have as low noise as possible. There was also a requirement to power the device via USB 5V but I don't know if it will be possible.

    I have currently problems obtaining via Webench the right +-36V rail converter for the analog part that will consist of a constant current pulsed generator obtained via two opamps in Howland Current Pump configuration. The 36V is the voltage compliance needed to have at least 30mA current on a 1k ohm load.

    Reaching +-36V from 12V seems a non trivial task for me, imagine from 5V. The Webench configurator is confident using at least 22V input.

    I have now created the +24V and -12V for the DAC using a TPS55340 from the MAIN 12V DC input

    Is it allowed to tap from the +24V for the DAC the input for the analog stage in a "cascaded" way?

    I am not so confident that using such a configuration wouldn't bring noise inside the DAC that is known to need "clean" power rails.

    Best regards and thanks.

  • Hi Stefano,

    Sorry, i have not understood your question, but have you already checked our available reference designs.

    I think there are some very close to your requirements and all of them are already tested.

    I made some preselection on the requirements - I have understood:

    TI Reference Designs Library

    (Sometimes it is easier to loosen the spec to get better suggestions which may filter away otherwise.)

    Best regards,


  • Thank You, Stefan. Really appreciate the link. Now I can study more practical design and find useful material for my goal. best regards and thanks