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TPS92074: Is it possible to supply additional circuits from the VCC

Part Number: TPS92074

Dear TI-forum,

I would like to feed additional circuits (like a micro controller generating a 0-3V dim signal). If so, what is the maximum current I can draw?

Thanks,

Frits

  • Hello Frits,

    It depends on how well the VCC generating MOSFET can dissipate power. If your input is 120VAC, average will be 108V. If VCC is at 12V that leaves 96V across the MOSFET. Every 1 mA used from VCC will cause 96 mW of power dissipation in the MOSFET.

    Best Regards,
  • Hi Erwin,
    Thanks. Our design will most of the time operate from 230VAC. For some countries, like US, on 120VAC. The chip that I want to use the Vcc supply for will draw most of the time a few micro amps, but on regular intervals at most 20mA for about 100us. Duty cycle 100ms. Now that I know that I can use the Vcc circuit I will make the necessary calculations as you suggest. Most likely with a more suitable MOSFET. As mentioned in my other post I will order an evaluation board and do some experiments as well.
    Thanks,
    - Frits