wuchy143
Member
Hi,
I'm using a simple FET hardware soft-start for my current 5V design. The Fet needs to supply ~200mA to the +5V rail which will power up my entire PCB. Which essentially means that there will be 200mA flowing across the FET.
I proto'd up my system and when I take my voltmeter and measure across the source and drain of the FET I read 0V across the FET. Now I doubt it's really 0V probably in the mV range.
From what I'm seeing it appears that I'm drawing negligible power across the FET and should not provide a heatsink. Even now when I have it powered up it isn't hot at all.
Theta(ja) for this part is = 42 degrees C per watt.
Is this a correct approach to ensuring I do not need a heatsink?
attached is my schematic(simplified)
Thanks
I'm using a simple FET hardware soft-start for my current 5V design. The Fet needs to supply ~200mA to the +5V rail which will power up my entire PCB. Which essentially means that there will be 200mA flowing across the FET.
I proto'd up my system and when I take my voltmeter and measure across the source and drain of the FET I read 0V across the FET. Now I doubt it's really 0V probably in the mV range.
From what I'm seeing it appears that I'm drawing negligible power across the FET and should not provide a heatsink. Even now when I have it powered up it isn't hot at all.
Theta(ja) for this part is = 42 degrees C per watt.
Is this a correct approach to ensuring I do not need a heatsink?
attached is my schematic(simplified)
Thanks