Electronics > Beginners
PCI-e Power - resistance??? / cheap+efficient HS Current limit
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HeartOfGermany:
I am trying to implement a TL494 for a 12-24V Boost converter with a continous power output of 120W (200W peak for >50ms / <20% of the time).

There is however one problem. I want to get the booster working and have no proper way to verify some parameters.

The TL494 is configured, to switch off for a short time, if the voltage drops below 10V on the TL494.

The configuration is as follows in my simulation:

PCI-e 6 Pin Power input: 12.6V at 100mOhm, PCI-e Power input via PCI-e Connector 200mOhm. This however gets spikes into the output capacitors (10x1mF [100mOhm/capacitor], 10x 10uF [50mOhm/capacitor] for higher frequency). The spikes rise to a max of aproximately 60A!!! This also means a very very high current on the input. This could lead to system instability or even crash the PC...



What is a realistic resistance on the PCI-e connector VCC and the PCI-e 6 Pin? 12.6V is idle voltage on many supplies. Definitely would drop a bit... Whatever.


I would love a very cheap IC (tiny+SMD!), that just gives a logic output. The lower, the detect voltage is, the better for efficiency. It is absolutely required, to be a very low voltage drop detecting high side current monitor with digital output (don't mind, if output inverted or so). The V_detect should be less than 60mV for a max of 1W of TDP for the shunt.

Thank you.
HeartOfGermany:
Hey, biggest E-Forum in the WWW I guess, but no one knows, how to current limit? I doubt it. ;)
thm_w:
Its a bit hard for me to understand what you are doing.
It sounds like you are trying to power a boost converter, using a PC power supply from 6 pin PCI-e connector, and are worried about the high surge currents. Thats a valid concern.

In PCs/servers usually you will see something called "hot swap IC", https://para.maximintegrated.com/en/results.mvp?fam=hot_swap which can limit the current.
There may be other ways to approach this as well: https://www.electronicdesign.com/power/use-smart-load-switches-current-limit-protection
But usually hot swap stuff is optimized for low voltages and very high current found in PCs.
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