Cause of failure of DCDC modules?

Hi,
We are powering some circuitry at some 5W on a 5V rail with a Traco DCDC module (THL 20-4811WI).
Its output is diode OR’d with the output of a XP Power DCDC module which is part number JTK3048S05. This is just in case the Traco DCDC module fails.

The circuitry being powered is a radio Transceiver and a micro.

Since the load is less than 50% of the DCDC modules’ rated power I asked why we were bothering to have the redundancy in DCDC modules. (The temperature of the module was not exceeding the datasheet rated temperature.)

The answer was that the DCDC modules had failed in the past. This company uses no ESD protection. Would you agree that the most likely reason for the failure of DCDC modules, which are not running at overtemperature, is ESD damage?

The DCDC modules have, on the PCB near to them, electrolytic input capacitors, and a mixture of ceramic SMD and SMD aluminium polymer caps at the output.

JTK3048S05 datasheet:
https://www.xppower.com/portals/0/pdfs/SF_JTK30.pdf

THL 20-4811WI datasheet:
https://www.tracopower.com/products/thl20wi.pdf

You might want to use a DSO in one shot mode, and trigger off power rails to see
what power up/down transients look like. Do same for any DC/DC control signals.

This should show if any L effects in loads causing HV transients.


Regards, Dana.

Hi,

What is:
*"some module" and how is it's wiring? Show a schematic.

zenerbjt said:

the DCDC modules had failed

Click to expand...

What does it mean? Which module failed and how?

zenerbjt said:

Would you agree....

Click to expand...

No.
ESD is low energy..
What ESD voltage at which pin with respect to which pin....is your failure mode idea?

You don't say anything about input power sources. Tell us about them.

Klaus

Failure analysis would tell the cause, sounds like
that was not done so nobody knows nuthin' and
slapping a Band-Aid on it is all that resulted.

ESD -can- damage converters (like if you blew
out the enable input?). But "can", "will" and "did"
are not the same thing and designing against
"can" wants some idea of the odds, to say whether
it's worthwhile - otherwise it's chasing speculation.
"Will" ought to follow from "did" and sample size.
"Did" is where you get your material to analyze
for root cause of failure, and maybe learn how
not to.

... is your alternate name Treez ... ?

... is your alternate name Treez ... ?

Click to expand...

Thanks but no its not.

What ESD voltage at which pin with respect to which pin....is your failure mode idea?
You don't say anything about input power sources. Tell us about them.

Click to expand...

Input is 48V Lithium battery
ESD with respect to any pin that may damage the DCDC modules linked in the top post.

I was thinking that once a DCDC module is soldered into a PCB, with input and output capacitors at its input/output...then its probably almost impossible to do ESD damage to it then?...as the caps would soak up any ESD voltage?
The only ESD risk concerning the JTK3048S05 DCDC module is the TRIM pin resistor...and presumably putting a cap across this resistor makes it very hard for ESD damage to occur to this pin?

First you ought to determine whether the failure
mode(s) is/are explainable by pin ESD. Mitigation
follows from mode.