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fogSource

Analog or digital PSU?

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Posted · Original PosterOP

I've seen occasional posts mention the terms "digital" or "analog" in relation to PSUs but I can't find much info about the differences or history..    

 

Like are any of the Tier S or A PSUs analog? 

Or is everything digital/"semidigital" now?  

 

 

Are certain manufacturers partial to certain designs?  If so who makes the best analog and who makes the best digital right now? 

 

I am not asking if "digital is better than analog".

 

 

 

 

 

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As far as I know, ALL power supplies are analog AND digital. Mains power is, by default, an analog signal. That signal goes through a transformer to drop it down to something usable inside the power supply. Then that signal goes through a rectifier to make it into a DC signal (Digital). There are a shit ton of filter caps and protection diodes in there as well.

 

Then, that DC signal... probably around 18 V or so, is fed into a 12V regulator to get 12 V. I'm unsure if that 12V is then fed into a 5V regulator, or if the 5V regulator just gets the full 18V, probably the ladder to avoid having to have a huge 12V regulator. And that's how you get your voltages. There are multiple 12V and 5V regulators in the power supply. As well as smaller regulators for 3.3V. -12V may be generated simply by switching the polarity of ground to the 12V rail, but I THINK it has it's own circuitry to generate it honestly. 

 

The only real difference I've noticed in power supplies over the last decade is switching vs linear regulators. Linear regulators are an older technology and ESSENTIALLY just waste excess power as heat. Switching regulators switch on and off instead and can be much more efficient. I'm 95% sure that all modern power supplies are of the switching variety. 

 

It's very hard to look at a power supply and say "that's analog" or "that's digital" when in reality we have no adjustment to it. Analog power supplies used to be controlled by potentiometers (variable resistors). Digital power supplies are controlled by microcontrollers, but they both do the same thing... provide a very specific voltage and amperage. 

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7 hours ago, corrado33 said:

As far as I know, ALL power supplies are analog AND digital. Mains power is, by default, an analog signal. That signal goes through a transformer to drop it down to something usable inside the power supply. Then that signal goes through a rectifier to make it into a DC signal (Digital). There are a shit ton of filter caps and protection diodes in there as well.

Holy shit. No.

 

AC does not stand for "Analog".  DC does not stand for "Digital".  AC stands for Alternating Current (what comes from your wall) and DC stands for Direct Current (what your electronics need.

 

7 hours ago, corrado33 said:

The only real difference I've noticed in power supplies over the last decade is switching vs linear regulators. 

Holy shit.  No.

 

PC power supplies have always been switch mode.  I mean... A Commodore 64 use a linear PSU, but......

 

8 hours ago, corrado33 said:

Analog power supplies used to be controlled by potentiometers (variable resistors). 

Holy shit.  No.

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9 hours ago, fogSource said:

I've seen occasional posts mention the terms "digital" or "analog" in relation to PSUs but I can't find much info about the differences or history..    

 

Like are any of the Tier S or A PSUs analog? 

Or is everything digital/"semidigital" now?  

 

 

Are certain manufacturers partial to certain designs?  If so who makes the best analog and who makes the best digital right now? 

 

I am not asking if "digital is better than analog".

The actual means by which a PSU converts AC to DC is relatively unchanged between analog and digital.  There are different TOPOLOGIES like double forward, resonant mode LLC, etc., but that doesn't mean one PSU is digital vs. analog.

 

What changes is how the PSU's switching is controlled.  Whether they use an analog IC (like an analog PWM controller, for example) or an actual MCU.

 

Essentially, 99% of the PSUs out there are analog.  The cost delta between an analog IC vs. a digital MCU is like 20 cents versus $5.  So you're not going to see digital controllers in your $99 Gold PSUs.  Also, it's unnecessary.  Usually, digital control of the switching frequencies is only needed to achieve very high efficiency.

 

An analog controller is pretty straight forward on what it needs to do.  A digital controller like the kind TI makes to drive digital totem-pole PFC, for example, allows switching frequencies to change quickly under different loads.  On the secondary side, an analog IC basically takes 1 or 0 input to determine a 1 or 0 result.  Digital PSUs can take data from teh output voltages and report back to the PSU as to how it could function better.

 

Currently, the only truly digital PSU on the PC desktop market is the Corsair AXi.  But the server market has many digital PSUs from the likes of Delta, Lite-On, etc.

 

Some PSUs call themselves "Digital" because they have an IC that analyzes data to report to the user, but since the rest of the PSU is actually analog, it can't actually control how the PSU works.  For example:  The NZXT E Series PSU and the Corsair HXi PSU aren't really digital.  They're still analog.  But they both have an IC that can read output voltages, output power, etc. and report it to the user via software.  

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13 minutes ago, jonnyGURU said:

Holy shit. No.

Holy shit.  No.

Holy shit.  No.

Holy shit.  No.

TL;DR;

 

(This is a joke, please go read what this angry pixies magician actually said)


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52 minutes ago, givingtnt said:

TL;DR;

 

(This is a joke, please go read what this angry pixies magician actually said)

I did.  If it's humor, it's incredibly dry.

 

Why would I not get this humor?

 

Because there are people out there that could potentially believe this stuff.

 

I mean... think about it.  We have flat earthers.  People that believe the sun is only 2000 miles away.  That the earth is only about 3000 years old.  That there was no moon landing and certainly no Mars rovers because Mars is nothing more than a "wandering star".

 

My faith in humanity is so completely shattered and if someone told me they believed that on the other end of their home's power receptacle was a goat's anus hiding in the wall that the plug fit into and that it shit out alternating current, I would nod and say I feel sorry for their offspring.

 

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Posted · Original PosterOP

OH wow lol, jonnyGuru is in my thread making jokes about conspiracy theories, I'm honored.  Also thank you,  it makes a lot more sense now.  

 

 

Funny you mention conspiracy theories.  Part of why I asked this question is I was curious what kind of PSU would be hardest to "hack" lol

 

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23 hours ago, jonnyGURU said:

 

Essentially, 99% of the PSUs out there are analog.  The cost delta between an analog IC vs. a digital MCU is like 20 cents versus $5.  So you're not going to see digital controllers in your $99 Gold PSUs.  Also, it's unnecessary.  Usually, digital control of the switching frequencies is only needed to achieve very high efficiency.

 

 

I thought it was also good for having better voltage regulation,

 

as for ripple, I don't know

On 12/14/2018 at 9:25 AM, jonnyGURU said:

 

 

An analog controller is pretty straight forward on what it needs to do.  A digital controller like the kind TI makes to drive digital totem-pole PFC, for example, allows switching frequencies to change quickly under different loads.  On the secondary side, an analog IC basically takes 1 or 0 input to determine a 1 or 0 result.  Digital PSUs can take data from teh output voltages and report back to the PSU as to how it could function better.


Currently, the only truly digital PSU on the PC desktop market is the Corsair AXi.  But the server market has many digital PSUs from the likes of Delta, Lite-On, etc.

2

I ever read:

 

"Digital PSUs often have lower switching frequencies than their analog counterparts, which might make a difference for our discussion. We’ll come to this soon."

 

https://www.tomshardware.com/reviews/graphics-card-power-supply-balance,3979-7.html

 

so digital psus have their drawbacks as well don't they?

 

On 12/14/2018 at 9:25 AM, jonnyGURU said:

 

Some PSUs call themselves "Digital" because they have an IC that analyzes data to report to the user, but since the rest of the PSU is actually analog, it can't actually control how the PSU works.  For example:  The NZXT E Series PSU and the Corsair HXi PSU aren't really digital.  They're still analog.  But they both have an IC that can read output voltages, output power, etc. and report it to the user via software.  

1

https://www.corsair.com/lm/es/blog/HXi_vs_AXi

 

i've never seen the HXi being considered DIGITAL:

 

While the AXi series enjoys digital power regulation, the HXi remains a more traditional, time-tested analog solution. Regulation is still extremely tight but can’t quite reach the precision afforded by the DSPs in the AXi units. The DSP is replaced instead by a DAC (digital-to-analog converter) to enable Corsair Link functionality.

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1 hour ago, 17030644 said:

I thought it was also good for having better voltage regulation,

 

as for ripple, I don't know

It can be.  Depends on how it's implemented.  Typically, it's implemented for higher efficiency.

1 hour ago, 17030644 said:

"Digital PSUs often have lower switching frequencies than their analog counterparts, which might make a difference for our discussion. We’ll come to this soon."

 

https://www.tomshardware.com/reviews/graphics-card-power-supply-balance,3979-7.html

 

so digital psus have their drawbacks as well don't they?

 

That's incorrect.  In fact, some GaN-FETs REQUIRE digital controllers for swiching.

1 hour ago, 17030644 said:

You saw who wrote that article, right?  Just checking.

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1 hour ago, 17030644 said:

 

i've never seen the HXi being considered DIGITAL:

 

Good for you.

 

I wasn't talking about the manufacturers calling them digital (while some manufacturers do call their analog PSUs digital just because they output to software).  I was talking about in general.  Like in forums.  Or resellers.

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1 hour ago, jonnyGURU said:

It can be.  Depends on how it's implemented.  Typically, it's implemented for higher efficiency.

That's incorrect.  In fact, some GaN-FETs REQUIRE digital controllers for swiching.

You saw who wrote that article, right?  Just checking.

so basically digital psus are a win win? when price is not an issue of course

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19 minutes ago, 17030644 said:

so basically digital psus are a win win? when price is not an issue of course

They're expensive.

 

That's why they're only used on the high end.... and servers.

 

But we may start to see more digital in lower end.  To meet new low load efficiency requirements and still hit audible noise and low ripple expectations.

 

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