How to test IEC61000 ESD for DC-DC power supply - Page 1
Forum section: electronics / projects

author: TimNJ
author_rank: Super Contributor
timestamp: December 09, 2019, 07:52:42 pm
content: Hi all,Does anyone have experience testing ESD according to IEC61000 (or any standard) for a DC-DC supply that is fed from another regulated switchmode power supply.When I've tested AC-DC converters, it's pretty simple because the AC source is the wall outlet (usually with isolation transformer in between). However, for DC-DC, we are using a rack-mount AC-DC converter to create the input voltage to the DC-DC supply. In this case, it looks like we are causing the source supply to glitch out during ESD pulses. We don't want the DC source to be affected by ESD pulses. Was thinking about using some sort of LC filter in between the source and the DUT, but I can't find much information about an actual, industry accepted test setup. Anyone have any experience?Thank you!Tim

author: T3sl4co1l
author_rank: Super Contributor
timestamp: December 09, 2019, 09:53:14 pm
content: So the source you're testing with, isn't ESD compatible? Yikes! (Not class A compliant, at least.)Probably put the source behind an ISN, maybe with some TVS (between lines, and to ground if applicable) if that's not enough.ISN is also recommended for doing induced noise, like EFT (61000-4-4).Tim

author: TimNJ
author_rank: Super Contributor
timestamp: December 09, 2019, 11:15:58 pm
content: Thanks Tim. I need to double check, but seems like the source we are using is not 100% tolerant to ESD pulses. It seems to drop out for a short period of time after the ESD event. It could also be our DUT, but initial troubleshooting seemed like the source was dropping out.It's a GWInstek rackmount source, which I'd think would be relatively robust. We'll see.So, maybe we'll use the same LISN/decoupling network that our EFT/surge generator has and see if that works, if that's what you're saying.Maybe that will do the trick.Thanks!

author: trobbins
author_rank: Frequent Contributor
timestamp: December 10, 2019, 04:11:15 am
content: What's the source DCV and current requirement?What's the application and nominal method of power source input?

author: coppice
author_rank: Super Contributor
timestamp: December 10, 2019, 04:29:00 am
content: Quote from: T3sl4co1l on December 09, 2019, 09:53:14 pmThere is plenty of compliant test equipment which still give you trouble during EMI, ESD and related testing. Not just power supplies, but things like scopes going crazy during testing. Compliance means they passed a test schedule, not yours.Quote from: T3sl4co1l on December 09, 2019, 09:53:14 pmThe snag with an ISN is that any impedance between the source and the unit under test can affect the performance of the unit under test, say when its impulse response is being tested, and it needs to pull rapid bursts of energy from the source. The LISN that is part of AC/DC supply testing isn't really a problem in this regard, as an AC source isn't capable of supplying rapid bursts of energy at arbitrary times, so the LISN can't mess things up.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: December 10, 2019, 11:35:41 am
content: I said "ISN" because this is low voltage, and an appropriate type would do; of which a LISN would be nice but not necessarily defined by any standard?Tim

author: TimNJ
author_rank: Super Contributor
timestamp: December 16, 2019, 06:25:46 pm
content: Thanks for your replies. I was away the last week, and asked this question before I left.After testing again, the DC source's voltage is actually stable...as (perhaps) expected for an industrial-grade/production-environment source. We tried with an LC network of about 2mH and 10uF, similar to the decoupling networks used in EFT generators, but did not help. This makes sense because it really has nothing to do with the DC source, as postulated.The DUT is a DC-DC power supply, input voltage range 9-36VDC, 100W output. Normal application is automobile/aircraft DC power.Thanks!

author: TimNJ
author_rank: Super Contributor
timestamp: December 27, 2019, 07:01:20 pm
content: Sorry for resurrecting my own thread.I am still wondering if there is an "accepted" test setup for ESD testing on a DC-DC power adapter. This is something I can ask our EMC lab about too...but I've found it difficult to get clear information from them, since they are located in China.Since an isolated AC-DC converter feeds the DC-DC DUT, it's hard for me to separate what part of our issue might be related to the DUT and what might be related to the DC source. The DC source maintains good regulation throughout the ESD event, but since the DUT is a Class II (double insulated) converter, I imagine that the ESD return path is somehow through the DC source (which is an AC-DC converter ). If we consider the DC source as "part of the DUT" then I'd imagine there could be a lot of variability in the test, depending on the lab and the source they use. The ESD return impedance to earth might be quite variable for different DC sources, I'd expect.At the end of the day, the unit should function well during the ESD event, regardless of what the source looks like, but I am still wondering if there's something more concrete I can refer to, for this particular situation.Thanks a lot.

author: Tomorokoshi
author_rank: Super Contributor
timestamp: December 28, 2019, 04:41:08 am
content: At ~$300/hour some consulting time with a local lab:https://www.nwemc.com/testing-capabilities/emi-emc-testingmight help with both interpretation of standards and test techniques. Then you can suggest and argue your case to the other lab in China.I wonder if the ESD events are interfering with the over-current shutdown circuit.I had a marginally similar setup with EMC testing of a DC-operated device powered from an AC-DC supply, such that we wanted to ignore the AC-DC supply, therefore all power-related testing was done directly to the DC-operated device. This is a much harsher to the DC-operated device than hitting the AC-DC supply directly.

author: jonpaul
author_rank: Super Contributor
timestamp: December 28, 2019, 01:24:04 pm
content: Hello againWhat is the rise time of the ESD pulses causing the problem?Very fast rise ESD is hard to track down, common mode can convert to normal mode noiseWe used a combination of ferrite beads and small geometry TVS diodes in medical electronics with 35 kV arc lamp ignitors inches away.Reccomend the white papers from Protek Devices.http://www.protekdevices.comFinally, in testing the energy and rise time of ESD Simulators must be carefully selected to replicate the problem in the field.Just the ramblings of an old retired EEGood luck!Jon