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THS3217: Vcc power up order

Kazuhiko Hirano
Genius 11613 points
Part Number: THS3217

Hello,

 

+VCC1, +VCC2, -VCC1 and –VCC2 can be powered up in any order?

 

Best regards,

 

K.Hirano

  • 0
    Guru 140200 points

    Hi Kazuhiko,

    please read section 11 of datasheet:

                                                "Operate the two positive supply pins and the two negative supply pins at the same
    voltage. Using separate sources on the two pins risks forward-biasing the on-chip parallel diodes connecting the
    two supply inputs together. +VCC1 (pin 13) and +VCC2 (pin 16) have two parallel diodes that are normally off if
    the voltage at the two pins are equal. The same is true for –VCC1 (pin 8) and –VCC2 (pin 5)."

    And:

    "The recommended external supply configuration brings ±VCC into the output stage first, then back to the input
    stage connections through a π-filter comprised of ferrite beads and added decoupling capacitors at +VCC2 (pin
    16) and –VCC2 (pin 5). Figure 106 shows an example decoupling configuration."

    Kai

  • 0 in reply to kai klaas69
    Guru 47485 points

    Incidentally, the separate supply connections for the output stage and input stage simulated to show incrementally improved HD performance vs using only one supply pin - that showed up in the full package model simulations. 

    Those Ferrite beads are not really 4uH inductors as shown, but lossy inductive elements, you might look at the EVM BOM to get a part number. 

  • 0 in reply to Michael Steffes
    Guru 140200 points

    Now, if we talk about the EVM...

    The EVM shows a much better layout compared to the "layout example" of datasheet. The "layout example" of datasheet has vias in the solder pads which I do not like at all due to soldering problems:

    The EVM layout, on the other hand, does not have this:

    Kai