EEVblog Electronics Community Forum
Electronics => Beginners => Topic started by: garethw on July 29, 2019, 07:26:18 pm
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Reading the data sheet of an STM32F0 reveals they have the option of supplying the analogue peripherals with a separate power supply. This got me thinking about the power supply requirements for my current project.
My question is this, is it common to use a switched mode power supply to step an input voltage down and then drop the final voltage with a low noise LDO? I’m thinking of stepping down an input voltage from 6-12V down to 5v and then to 3.3 using a couple of LDOs to prevent too much heat as I’m measuring temperatures amongst other things.
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LDOs to prevent too much heat
:palm:
LDOs do the same job as regular Voltage Regulators, convert excess voltage into heat.
The advantage of LDOs is that they can be used with a lower input voltage for regulation.
Yes, it is common to use switching regulators followed by Vregs to create multiple voltage rails.
It can also be done with multiple switching regulators as well (more efficient if it does not mind the noise)
Vregs are not a good choice when battery powered.
If powered via mains psu and heat can be managed, Vregs can be ok and easier to use than switching regulators
Micros do not mind too much if you feed them with noisy power rail.
ST, like many chip makers, provide for a seperate power supply section for noise sensative parts of the chip, eg ADCs or DACs
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LDOs to prevent too much heat
:palm:
LDOs do the same job as regular Voltage Regulators, convert excess voltage into heat.
The advantage of LDOs is that they can be used with a lower input voltage for regulation.
I am aware that an LDO is a conventional linear voltage regulator. What I meant was that stepping down the voltage with a SMPS produces less heat than doing so by the LDO alone.