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LM5020: Oscillator: RT resistor values? recommendation for DCM/CCM?

AnBer
Mastermind 30170 points
Part Number: LM5020

Team,

1) About RT recommendation in SNVS275F: http://www.ti.com/product/LM5020
It seems that there are some differences between the 'Electrical specs: Oscillator" table (page 4) and the Fig 5 "Osc Freq vs RT" (page 5).
-Which one should be used?
-Can you confirm that the below is possible?
         30k < RT < 100k
-What is the lowest possible Osc frequency and what RT value need to be used?

2) Any recommendation to use DCM, CCM and control the duty cycles at 50%?

3) How could two LM5020 be synchronized together?
The idea would be to have the PWM of the two LM5020 to be 180Deg interleaved. Is it possible and how?

Thanks in advance,

Anthony

  • 0
    TI__Mastermind 21720 points
    Hi Anthony

    Please be aware that there are two versions of the LM5020. The LM5020-1 and the LM5020-2

    The LM5020-1 frequency settings are described in the electrical characteristics table on page 4 and in figure 5 on page 5. The LM5020-2 switching frequency follows the same trend as figure 5 but is half the switching frequency as described by note 3 of the electrical characteristics table. The lowest recommended switching frequency for the LM5020-1 is about 65kHz per the graph in figure 5.

    For the other two questions please send over the application specifications. This will help to determine if CCM operation or DCM operation is correct for you application.

    Is is not typical if interleave two flyback regulators.

    Thanks,

    Garrett