New HDPLEX 200W LPS

[octaviars]

25 minutes ago, austinpop said:

Which suggests that the HDPlex uses switching regulators on these rails?

 

The big span of output voltages on the new HD Plex (3.3V/5V/7.5V/9V/12V/15V) from the LT3045 board would be impossible when the input to the board is 16V and needs a pre regulator as the voltage drop is so big. A switching DC/DC converter can do big voltage drops without producing much heat.

 

If this is done right it should work and not make much difference from a true linear supply.

 

Here is what John Swenson wrote about it.

 

 

 

[octaviars]

This is what John wrote regarding DC/DC converters as there will be some of those in the new etherREGEN. 

 

"First off some clarifications about the differences between SMPS and DC/DC switching regulators. An SMPS plugs into the mains, it chops up the mains voltage into high frequency pulses, feeds that through a transformer, on the other side rectifies the high frequency pulses coming from the transformer, filters it into fairly clean DC, measures the DC and sends a feedback signal through another transformer or optical coupler to the front end to modify the pulse width so the DC output voltage is correct.

 

These have low level high frequency noise on the output AND input, but also have both high impedance and low impedance leakage current from the AC line to the DC output. This is what causes a lot of the issues with SMPS, NOT the high frequency noise on the output.

 

A DC/DC converter does NOT connect to the AC mains, its input is DC from some other power supply. Their purpose is to convert one DC voltage to another (either up or down). Their big advantage over a linear regulator is that the POWER is constant, not the current. With a linear regulator the current going in is the same as coming out. With a switching DC/DC converter the current going in depends on the power on the output.

 

Say for example you have 10V coming in and you want 1 volt coming out. If your load takes 1 amp, a linear regulator will need 10V at one amp on the input, that means 9 watts of power are dissipated in the regulator (ie a BIG heat sink). With a DC/DC converter the power on the output is 1 watt (1V x 1A = 1W). So on the input it takes 1W / 10V = 0.1A. Now in reality the converters are not 100% efficient, maybe say 85%, so the power needed by the input will be a little higher, in this case 1.15W, so the input current is 0.15A. This means the DC/DC converter is dissipating 0.15W instead of 9W, 60 times lower!

 

The DC/DC converter DOES have high frequency output noise, but it is usually at a much higher frequency than an SMPS. SMPS usually run at 40KHz to 70KH, DC/DC converters usually run at 500KHz to 1MHz. This is a big difference. At 60KHz a filter is fairly large and costs some money. The same amount of attenuation at 1MHz takes very small very inexpensive components. The result is that IF you use a filter on the output, you can get a huge attenuation for very small board spaceand cost when using a DC/DC converter. Of course you DO have to spring for the filter, very cost constrained devices usually don't.

 

The DC/DC converter does NOT create any extra leakage since it is not connected to the mains. Whatever leakage exists from the power supply is still there, the DC/DC converter does not attenuate it, but it doesn't increase it either.

 

With a DC/DC converter you can always add a linear regulator after the converter, good ones can decrease the high frequency noise from the converter by 80-100dB. So a combination of the filter AND a linear regulator reduces the high frequency output to much less than the inherent noise of the regulator, it is essentially gone. So if properly implemented a DC/DC converter does not have any down side and it drastically reduces the amount of heat that has to be dissipated.

 

All that said, very low cost devices are not going to go to any of those measures, they are going to use a cheap DC/DC converter and and feed the output directly to the chips.

 

On the etherRegen, there ARE a few DC/DC converters in the design. But they have the good filters and very good linear regulators after the converter. I have tried using some very sensitive test equipment and have not seen ANY sign of the DC/DC converter on the final DC.

 

One other issue with DC/DC converters is EMI, the converter can radiate high frequency signals that can be picked up by other traces on the board. I am using some very special converters that have extremely low EMI, I can JUST barely measure it, where I can measure strong emission from other converters. Even though the EMI is so low I am laying out the board so that pickup by other signals is quite small. Again I have not been able to see any hint of this in prototypes.

 

The whole reason for using the DC/DC converters is to drastically cut down on the amount of heat the box has to dissipate, AND the high cost of getting the heat from the regulators TO the heatsinks.  I'm quite confidant that this is done in such a way that there will be NO impact of this on the operation of the device.

 

John S."

[octaviars]

I have the old 200W modell (No LT3045 and the 19V outputs share the ground). I have encountered some problems with it.

 

First: I run all four rails and power ISP fiber modem with 5Vdc, router with 19Vdc, switch with 12Vdc and a NUC with Roon ROCK with 19Vdc and all loads are small perhaps 1.5A on 5Vdc and around 1A on 19Vdc and it runs hot and by that I mean so hot I think it will be damaged by it so I cool it with a fan, no big deal but to run 10A on the 19Vdc rail I think it will have a meltdown

 

Second: Twice after some power surge or something on the net it has shutdown and needed to be powered down and restarted to put out power again but this is normall I think as the circuits to keep it safe are working (fingers crossed that it will do this if something goes really wrong).

 

Third: Both my 19Vdc outputs stoped working (both the 19V and the 19-5V at the same time). I contacted Larry and he directly told me it was the potentiometer at the back that changes the 19-5V output that was broken (it was broken as the ohm was really strange on it and this affects both 19V outputs) he sent me a replacement (not exactly the same one) and this new one was not made to be mounted through a hole so I bought one from Elfa distrelec that was the exakt same one that was originaly mounted and soldered yhis one in and it works as it should right now.

 

If you look on forums there have been lots of problems with the old 160W and the old 200W so once again see this with the new 200W is a bit well not so good. To put four rails in this small box and the be able to draw this amount of power from them is perhaps not the best way of doing things.

[octaviars]

I hope to get my new PSU tomorrow (replacing the old 200W) anyone here using all four outputs on it with modest loads (NUC, router, switch etc.) and how hot does it get? 

[octaviars]

@dctom good to know. I use a 120mm fan to cool my PSU as all my network equipment is in a cabinet,think I will keep using it.

 

[octaviars]

2 hours ago, No Disc said:

Does this sound like it will need to be sent back for repair?

 

This also happened to mine. It is the potentiometer that is used to change the voltage that is bad. This will affect 19V and the adjustable 19V. 

It is not that hard to find the right potentiometer and solder of the cable and put a the new one in.