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UCC24630 / CCM operation during fixed frequency

Pao Wu
Intellectual 920 points
Other Parts Discussed in Thread: UCC24630

According to UCC24630 spec, it mention

 

“Do not use the UCC24630 in CCM designs that are operating in CCM while the flyback controller is operating

in variable frequency, FM, modulation. The CCM dead-time function is compatible with CCM operation during

fixed-frequency, PWM operation.”

 

Could we use CCM+Green mode for primary main PWM?

Multi-mode  PWM  controller  which could  operate  in  continuous  Current  Mode  (CCM).
Together  with  its  green  mode  operation  during  light load.

  • 0
    TI__Expert 4015 points
    Hi Pao,
    It depends on the frequency characteristic of the primary side controller. What is the part number of the primary side IC you are considering.
  • 0
    TI__Mastermind 23155 points

    The main consideration of the primary controller is if the control is a fixed frequency in high load conditions, or if the frequency is variable in the high load conditions.

    The UCC24630 is compatible with many controllers that have green mode operation. Operation at lighter loads in DCM operation, with variable frequency is not an issue with the UCC24630. Where there is a concern, is if the primary controller can be in variable frequency operation when the converter is operating in CCM, usually at higher load conditions.

    Many controllers have a fixed frequency operation (65kHz, 100kHz, 130kHz) at the high load conditions; and also have green mode operation.

    There are also controllers that have a "peak power" mode where the frequency increases during the high load conditions. This type of control is more likely to cause issues with the UCC24630 dead time control, which is based on previous cycle information.