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TPS54361: Select Switching Frequency

vinoth kumarG
Prodigy 20 points
Other Parts Discussed in Thread: TPS54361

              I have a question regarding the buck regulator TPS54361. I am going to use this IC for variable voltage Regulation.Input Voltage Max=60V, Output Voltage=5V to 48V ,Maximum Load Current 3Amps.I dont know ,how to choose Switching frequency that will be reliable for both high and low output voltage.

  • 0
    TI__Mastermind 28220 points

    There are 3 factor for choosing the switching frequency:

    1- EMI/EMC depends on the system. The swiching frequency fundamental can interfere with some frequency band and it is depends on system requirement

    2- Min on time typical value is 100nS should not be violated. This happens at high input voltage and low output voltage i.e VIN = 60V and VOUT = 5V. the formula is in the datasheet page 30. If the On time is violated the duty cycle will not be constant and AC ripple voltage is higher

    3- Switching and gate charge  losses are higher with high switching frequency. The formulas are in datasheet page 40

  • 0 in reply to Mahmoud Harmouch
    TI__Guru**** 191445 points

    One other thing you should consider.  TPS54261 is a current mode control device.  For current mode control, the power stage gain varies with the output voltage.  While it is possible in general to compensate the loop for that wide variation in output voltages that you seek, you would be better off to choose a voltage mode control converter.