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Original question:

UCC28950: To know the min switching frequency and max resistance on RAB/RCD

UCC28950: UCC28950 minimum switching frequency in slave mode

Steffen Theobald
Prodigy 10 points
Part Number: UCC28950

Hi,

according to the related thread "UCC28950: To know the min switching frequency and max resistance on RAB/RCD" it's possible to run at lower frequency than 50 kHz.

What is the minimum frequency at which the UCC28950 will work? Is ist possible to run at 20 or 30 kHz?

Thanks in advance

Steffen

  • 0
    TI__Guru* 85406 points

    Hello,

    Figure 35 of the data sheet shows the characterized frequency range of the UCC28950.  50 kHz appears to be the minimum frequency this device should be used at.

    Regards,

  • 0 in reply to Mike O'
    Prodigy 10 points

    Hello,

    Thank you for the promt reply. I know the information from the data sheet (minimum switching frequency is 50 kHz). But in the other thread, Colin mentioned that it would be possible to use lower switching frequencies if the UCC is configured in slave mode. So my question is what is the limiting factor and what frequency is possible for the UCC to still function stably?

    Thanks

    Best regards

    Steffen

  • +1 in reply to Steffen Theobald
    TI__Guru* 85406 points

    Hello Steffen,

    If it does work as Colin mentioned it is not characterized or guaranteed to match data sheet parameters or tolerances.

    What the limiting factors are generally the current mirrors that  product the timing inside the IC.  With external timing resistors the current mirror current can be adjusted to adjust the charging of the internal timing capacitors.  These currents have a limited range of what they can be adjusted too.  This is why the characterization curve was given.

    Regards,

  • 0 in reply to Mike O'
    TI__Guru* 85406 points

    Hello,

    As stated the device is characterized to work base on data sheet parameters.

    Regards,