Electronics > Projects, Designs, and Technical Stuff
voltage regulator with crazy specs: drop max 50mV, Vout = 2V, startup at 0.7V
magic:
Not bad.
--- Quote from: tatus1969 on August 16, 2019, 09:41:11 am ---When modifying it such that the voltage regulator is connected across the MOSFET, instead of being connected to the input terminals, then this could actually become a real two-terminal (almost) ideal diode. I wonder if that has been done before.
--- End quote ---
I thought about it and I think it hasn't been done before and I will tell you why: because then another ideal diode is needed to power the boost converter while protecting it from reverse bias. Kinda "you can have an ideal diode if you have an ideal diode" thing :)
Maybe there is some way to do it but probably not as simple as demanding ground connection.
capt bullshot:
--- Quote from: tatus1969 on August 16, 2019, 09:41:11 am ---Actually your side cut regarding the additional terminals gave me another idea. The current circuit stops bootstrapping as soon as the input voltage is high enough for permanent operation, but it could actually be a good idea to drop that function. When modifying it such that the voltage regulator is connected across the MOSFET, instead of being connected to the input terminals, then this could actually become a real two-terminal (almost) ideal diode. I wonder if that has been done before.
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http://www.ti.com/product/LM74610-Q1
These use an interesting kind of oscillator that starts at 20mV:
https://www.analog.com/media/en/technical-documentation/data-sheets/LTC3108.pdf
tatus1969:
--- Quote from: capt bullshot on August 29, 2019, 08:50:56 pm ---http://www.ti.com/product/LM74610-Q1
--- End quote ---
That's why I love this forum, someone always has the answer. That's exactly what I need, and it does everything that my current circuit does in a single chip. Startup at 0.48V is also low enough for my MOSFETs. Available, price okay, demo board ordered :-)
--- Quote from: capt bullshot on August 29, 2019, 08:50:56 pm ---These use an interesting kind of oscillator that starts at 20mV:
https://www.analog.com/media/en/technical-documentation/data-sheets/LTC3108.pdf
--- End quote ---
I've come across these in the past and had forgot, but the price of these is prohibitively high. Still awesome technology.
tatus1969:
--- Quote from: capt bullshot on August 29, 2019, 08:50:56 pm ---http://www.ti.com/product/LM74610-Q1
--- End quote ---
That chip appears to have one caveat for my application, as it needs 'significant' reverse voltage before turning off the MOSFET. It's only 20mV, but this translates to 30A of reverse current. That would make the solution 'a bit' less than 'ideal'. I might still get away with that because that controller naturally duty cycles the MOSFET, and the period can be adjusted to maybe 100ms. This would reduce backfeeding duration, as many power supplies don't like that.
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