General > General Technical Chat
5V linear reg with high max input voltage(>35V) and low quiescent draw(<200uA)
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Psi:

--- Quote from: mikeselectricstuff on August 28, 2022, 10:50:44 am ---Do you really need 1A and 35V in? That would dissipate way too much heat to be practical.

For lower currents, LP2951 isn't bad - 30V and 75uA Iq, but only 100mA out

--- End quote ---

There's a couple of 5V to 24V DCDC bricks that run off it, so it does need at least 400mA.
But yeah, I just picked 1A to give it some extra room.

The 7805 used now does get very warm, but it's on a large 6 layer 3oz pcb, so isn't really a problem.

I think the solution is to split the power rails up a bit. Have a lower current reg to run the MCU that has low quiescent and then a pfet to switch on a 7805 that controls everything else.

I was more just curious why there wasn't a cheap drop in 7805 replacement with much lower quiescent.
Given the 7805 is very old tech.
ryan_zheng:
If I understand it correctly, you are ultimately generating multiple 24V rail and a 5V rail, from a 12V automotive system. Why not generate both the 24V and 5V from the 12V rail?
Psi:
The isolated 5V-12V DCDC bricks input range was too narrow for automotive 12V
Zero999:

--- Quote from: Psi on August 30, 2022, 07:53:05 am ---The isolated 5V-12V DCDC bricks input range was too narrow for automotive 12V

--- End quote ---
Then swap them for some which can work over a wider voltage range. They're fairly common.
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