EEVblog 1550 - Keysight E36731A Battery Emulator Teardown

[EEVblog]

Teardown the new Keysight E36731A Battery Emulator & Profiler

https://www.keysight.com/us/en/product/E36731A/battery-emulator-and-profiler.html

[klemmi]

Hi,
just saw the teardown.
I am new here, hope that is the right place to post the question?

Why would you run the vias down to the edge of the board before connecting it to the filled area instead of taking the shortest path?
(first attached image)

Why would you run four individual vias instead one and then fan it out in the end?
(second attached image)

Markus

[EEVblog]

Hi,
just saw the teardown.
I am new here, hope that is the right place to post the question?

Why would you run the vias down to the edge of the board before connecting it to the filled area instead of taking the shortest path?
(first attached image)

Why would you run four individual vias instead one and then fan it out in the end?
(second attached image)

Welcome!
There could be more vias under the big connector, but generally you don't want vias under components as a general rule due to the invariabiliy in them wicking the solder paste away.
Also, shortest path doesn't really matter much in this case because it's all low frequency stuff we are talking about.
And in this case the majority of the current to the bottom side will going through the large mounting bolt.

The fours traces are what's called a star power (or star grounding) configurations. It's so that the currents to the various loads they go off to don't interact with each other and cause crosstalk or other issues.

[Rdx]

The thick bus bars coming over from the electronic load seem to have exactly the same interface on the PCB  as does the grunty output brass posts on the output board. They probably use the same brass output posts for when you only have the electronic load on its own.

What about those capacitor PCB replacements? May this be a thing that they only did pre-production models shipped to youtubers because chip shortage prevented them from getting the default capacitors? Or does this additional PCB with SMD caps have any other advantage?

[Kleinstein]

The PCB with the SMD capacitors may be a replacement for a THT foil capacitor. At least the footprint looks a bit like such a capacitor. The extra board may offer lower costs or better performance or just better availability.  There could be different versions (e.g. high voltage) that use a THT film capacitor instead. Having the SMD capacitors on a separate riser board helps to keep mechanical stress away from the capacitors. So I like the solution.  Large SMD caps directly on such a large PCB with heavy parts can be an issue.

[klemmi]

Welcome!

Thanks!

There could be more vias under the big connector, but generally you don't want vias under components as a general rule due to the invariabiliy in them wicking the solder paste away.
Also, shortest path doesn't really matter much in this case because it's all low frequency stuff we are talking about.
And in this case the majority of the current to the bottom side will going through the large mounting bolt.

Sorry, I mixed up wording. I meant trace not via.

If I would have to route it, I would just connect the trace at inner position (as shown in the picture below).

The fours traces are what's called a star power (or star grounding) configurations. It's so that the currents to the various loads they go off to don't interact with each other and cause crosstalk or other issues.

Ahhh, I did not realize it was a ground connection. That explains it. Thanks!

[floobydust]

I see the dedicated purpose of the unit, most things battery related. The S/W is $845/year am I right?
For the dollars, I think it should be a free maga PSU and load i.e. be able to emulate solar panels for MPPT testing. No hardware difference for the PSU. Why would you not have this instrument general purpose?
I can't find input or output capacitance spec for it because that affects the impedance relevant with batteries feeding boost/buck converters for example. If it's got a fair bit of added capacitance then your "low battery" emulator works better than the real thing.

Oh and the SMT heatsinks for the DPAKs, I tried using them in a design and they are not serviceable, impossible to desolder. A blow torch could do it but they are pretty much something needing reflow IMHO.

[thm_w]

If I would have to route it, I would just connect the trace at inner position (as shown in the picture below).

Dave mentioned "sense traces" but you may have not caught on, you can google "kelvin connection" for an explanation.

https://www.electroschematics.com/kelvin-connection/
https://www.allaboutcircuits.com/textbook/direct-current/chpt-8/kelvin-resistance-measurement/
https://www.sensortips.com/featured/kelvin-4-wire-sensing-solves-the-ir-drop-problem/

[nctnico]

There could be more vias under the big connector, but generally you don't want vias under components as a general rule due to the invariabiliy in them wicking the solder paste away.

From what I've seen so far with lead free soldering is that holes in thermal pads (like under QFN packages) don't wick any tin away from underneath the part. Lead free solder has very little tendency to flow compared to leaded solder.

[Rudolph Riedel]

What about all the stuff on the front panel?

[jc101]

I was really interested in this unit, but...

To use the Battery emulation and profiling, you have to *rent* a software licence per year to have access.  Access is all via a subscription licence model.

This costs ~20% of the unit cost per year.  You can rent (subscribe) for a 3-year licence for a small saving.

You never actually own the ability to use the Battery emulation and profiling ability.