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TPS54622: PVIN specification

Ella KIM
Expert 3862 points
Part Number: TPS54622
Other Parts Discussed in Thread: TPS54620

Hi taem,

I have several questions with TPS54622.

1. Recommended operation condition of VIN pin is 4.5 to 17V. What's the meaning of PVIN here?

 

2. What's difference between TPS54622 and TPS54620? It looks only difference is current protection scheme. Could you clarify the difference? And what's the recommended part between them for the new design?

Thanks,

  • 0
    TI__Mastermind 35115 points

    Hi Ella,

    PVIN is pin 4 and pin 5. I see these aren't shown in the simplified schematic on the front page but more description is given on the Pin Configurations and Functions section.

    Besides the current protection scheme (TPS54622 hiccup vs TPS54620 cycle-by-cycle), the other difference to point out is the internal reference. The TPS54622 has a 0.6V internal reference.

    Either part is recommended for a new design It depends on what is preferred in the application. Most applications seem to prefer hiccup protection and the lower 0.6-V reference of the TPS54622 so I would consider that one first. This is the trend for newer parts as well.

    Anthony

  • 0 in reply to Anthony F
    TI__Expert 3862 points

    Thanks, Anthony.

    I should have read thoroughly the datasheet..

    When it comes to the ref voltage, can I ask why the lower ref voltage is preferred in general? Is there a performance difference depending on ref voltage level?

  • 0 in reply to Ella KIM
    TI__Mastermind 35115 points

    Hi Ella,

    Two specific advantages which come to mind for the lower reference. First, the obvious one is it allows lower output voltages. Second, a feedforward cap has more effect the lower the reference is; specifically if we consider the frequency domain. A feedforward cap adds both a zero and pole to the loop. As the output voltage gets closer to the reference, the pole gets closer to the zero. So with a lower reference the pole is a higher frequency and the phase boost from the zero from the feedforward cap is increased. This should also have slight time domain or transient response performance effects as the higher frequency pole also results in slightly higher gain in the loop.

    Anthony