Power supplies and Microcontrollers - do they really get along?

[Th3_uN1Qu3]

I'm seeing more and more power supply projects using micros. I don't think that's such a good idea - i'm quite apprehensive of letting a device that runs code control an offline SMPS for instance... But i see them even in higher power devices like spot welders and they seem to do fine.

Have you had any first hand experience with microcontroller based power supplies? Is for instance a cheap PIC fast enough to run a 100kHz SMPS? I'd like to get started in micros and a custom SMPS controller sounds like a good idea. I have my own 555-based controller that i designed, but in some areas it leaves to be desired. A micro would allow for more expansion.

[redwire]

A PIC is fast enough but sensitive to EMI/RFI generated by the power electronics, which makes it crash. Your timer code must be perfect.

I rarely see all MCU type SMPS controllers. Any mistakes in your software, or an MCU crash can blow up the power-semi's. After the smoke clears the question comes up "what happened?" and you have no idea, it's too late. So testing and debug is very difficult.

Instead, I prefer a dedicated SMPS IC that gets controlled by an MCU (turn on/off/standby/Vout fine adjust etc.) If the MCU crashes or does something silly, no parts get damaged as the PWM IC keeps running and looks after things.

[PCBONEZ]

My computer needs a power supply but my power supply doesn't need a computer.
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[ratdude747]

sounds like a way to jack up the pricetag and reduce usable life...

spot welders i can understand, as you want to get the amount of heat and therefore the amount of juice right on target... you don't want to overheat the metal, just fuse it. the reason you might want a microcontroller is so you ca select the metal to be welded and you can measure the resistance to calculate the correct power... the resistance is critical to making a spot weld work in the first place.

[japlytic]

If I remember correctly, I have read about Gigabyte power supplies of which the output rails can be programmed.

[PCBONEZ]

I remember seeing some from someone? that called it 'programed' rails but in reality all it amounted to was adjustment pots to fine tune the OP voltage.

[Toasty]

The Delta DPS-700FB uses a PIC chip on the daughterboard. All the sense lines run into that board.

Which brings me to the question, can the PIC be reverse programmed? Is there a way to "get the code" and change the parameters?

From Scenic's post thread: http://www.badcaps.net/forum/showthread.php?t=5998

Pictures:
http://bambooz.pytalhost.net/badcaps...0/image016.jpg
http://bambooz.pytalhost.net/badcaps...0/image020.jpg
http://bambooz.pytalhost.net/badcaps...0/image028.jpg
http://bambooz.pytalhost.net/badcaps...0/image029.jpg

Toast

[Wizard]

Well, There are some plasma panel SMPSes that have microcontroller to show error by blinking a LED and some other functions.

Cheers, Wizard

[PCBONEZ]

Originally Posted by Toasty

The Delta DPS-700FB uses a PIC chip on the daughterboard. All the sense lines run into that board.

Which brings me to the question, can the PIC be reverse programmed? Is there a way to "get the code" and change the parameters?

From Scenic's post thread: http://www.badcaps.net/forum/showthread.php?t=5998

Toast

LOL, I actually have one of those but never needed to peek inside.
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