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There are several ways to implement the current/voltage control for an SMPS. The easy way I see is to use an ASIC/PMIC to manage the control loop. One of the other methods would be implement a PID control algorithm using a microcontroller and control the duty cycle of an SMPS.

I need some help in understanding the pros and cons of the above two methods in order to arrive at a justification of selecting one of the two methods.

Besides, if in case, there are control/communication/dimming requirements, then a PMIC with an MCU could also be used.

Please support me with some comparison.

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    \$\begingroup\$ I'm not sure I see any real difference between the two, other than the level of integration... \$\endgroup\$ Commented Sep 22, 2015 at 5:59
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    \$\begingroup\$ Advantages of Analog: speed, reliability, accuracy, fault tolerance (cannot get stuck on software bug). Advantages of digital: more flexibility after building hardware. In high-power SMPSes I dislike using an MCU, what if the software crashes and keeps the power FET on all the time. In an analog implementation the current limiting would prevent such disasters. \$\endgroup\$ Commented Sep 22, 2015 at 6:59
  • \$\begingroup\$ ASICs are very expensive unless you need thousends of them. There is a 3rd possibiliy: FPGAs. But I think a ready to use PMIC is cheap and much less error prone. \$\endgroup\$
    – Paebbels
    Commented Sep 22, 2015 at 7:01
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    \$\begingroup\$ A dedicated SMP chip is always my preferred solution. \$\endgroup\$
    – Andy aka
    Commented Sep 22, 2015 at 7:33
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    \$\begingroup\$ Although full digital control has flexibility, if the PID algorithm has a bug, the output may even oscillate, another type of disaster to be avoided. Dedicated controllers are plentiful and cheap. \$\endgroup\$ Commented Sep 22, 2015 at 7:41

2 Answers 2

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These are my general thoughts: -

  • Easiest - power management IC (PMIC)
  • Smallest footprint - PMIC usually
  • Cheapest - usually PMIC (for a certain minimum performance level)
  • Highest performance - PMIC will outshine all others
  • Best reliability - PMIC
  • Best stability - PMIC
  • Quickest reaction time to load changes - PMIC
  • Quickest reaction time to incoming voltage changes - PMIC

And now the bad things: -

  • Unreliability - microcontroller
  • Instability - microcontroller
  • Noisiest - microcontroller
  • Poor reaction time to load changes - microcontroller
  • Poor reaction time to input voltage changes - microcontroller
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    \$\begingroup\$ Software maintenance - Microcontroller \$\endgroup\$
    – Lior Bilia
    Commented Oct 22, 2015 at 11:36
  • \$\begingroup\$ Where will the microcontroller get its power from? Does the power supply need a power supply? \$\endgroup\$
    – Oskar Skog
    Commented Feb 17, 2017 at 13:50
  • \$\begingroup\$ @OskarSkog I feel I don't need to answer that! \$\endgroup\$
    – Andy aka
    Commented Feb 17, 2017 at 13:51
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    \$\begingroup\$ @Andy Aka: It's a rhetorical question. \$\endgroup\$
    – Oskar Skog
    Commented Feb 17, 2017 at 14:12
  • \$\begingroup\$ Everything you write is true but I feel like your answer lists reasons to "never build something you can buy an optimized off the shelf version of". If you compared a PMIC with a manually designed analog controller circuit (I know nobody does that but bear with me) you would basically get the same set of answers. \$\endgroup\$
    – jpc
    Commented Jan 30, 2021 at 12:31
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Imagine: your SMPS has to operate in arbitrary load conditions, most often in pulse loads; you need almost impossibly low ripple(<5mV), transient response almost in 1 cycle or a few, least amount of reflected input ripple, stable under all variations/tolerances, no electrolytic capacitors allowed, smallest size, almost flat efficiency across line/load. Meanwhile, please report all diagnostics to the host.

Get me a "dedicated" analog chip for this app please. I know, I know, you think'n, heck I can throw in this opamp, & that circuit you did for Julie…...while adding up hundreds of components. Now, you have an unproducible unpredictable SMPS - all for a few bucks.

You get the picture.

If your uncle Harry still needs an old fashioned 13.6V @ 100 amp, and will not mind fanning it, chilling it, throwing it away when not happy, I will get you a "dedicated" 50 cent chip for sure.

Using analog approach, none of the advanced control schemes can ever be implemented nor a system built with the demands I mentioned above, only to make you feel jittery if not annoyed.

Please don't.

That is what I have to deliver.

All shortcomings mentioned as to "microcontroller" based system are null & void off the bat.

YOU HAVE TO FIND APPROPRIATE TOPOLOGIES THAT MATE WITH AWESOME POWER OF DIGITAL SYSTEMS

That is the catch.

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    \$\begingroup\$ Welcome to EE.SE, Robin, but I've read this twice and I don't know what your message is. Please write in plain English. e.g., What does "null & void off the bat" mean in a technical context? (I'm a native English speaker but you are on an international site.) \$\endgroup\$
    – Transistor
    Commented Sep 13, 2018 at 21:47

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