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Need a help in selecting a current limit switch which is driven by a PWM signal

Suman Muralikrishnan
Prodigy 40 points

I need a suggestion in Load Switch where i have certain power to be transfered to a load of 7 ohm

Currently the power transfered is controlled by a PWM given to a mosfet at 500Hz. and voltage to load is 3.3 V

I need to limit the current if the PWM would go wrong or the load changes at any situation

I doubt if the same power could be delivered with the power switch since the rise time is large in load switches.

Suggest some IC which could do this work.

  • 0
    TI__Genius 15780 points

    Hi Suman,

    With a 3.3V voltage and a 7 ohm load, your current would be about 470mA.  The TPS22951 has a current limit of 600mA and can support voltages between 2.2V and 5.3V.  Please let me know if this load switch would fit your needs.

    Regards,

    Alek Kaknevicius

  • 0 in reply to Aleksandras_Kaknevicius
    Prodigy 40 points
    Thank you for your reply,

    I saw the specs of the IC but it has rise time of 41uS
    I am running my system in 500Hz so i have 2000ms time period of that the i use a minimum duty cycle of around 2% which is 400us ,
    The 41 uS is significant in the slot of 400uS which is around 10% change and thus the effective dutycycle would be 1.8% .
    This is a constraint for my system and is this would cause overheating for my load.

    Secondly the currents which flow through the switch are pulsating so does that require any RC Filter for the switch to get the continuous current.

    Suggest if any other approach could be applied for the system.
  • 0 in reply to Suman Muralikrishnan
    TI__Genius 15780 points

    Hi Suman,

    Unfortunately the TPS22951 is the only device we have which can support a current limit higher than 470mA.  Because the timing specs of that device do not work for your application, I am going to move this thread to the power interface forum since they have a larger selection of current limited switches.

    Regards,

    Alek Kaknevicius