Entry end ...
Just a joke. Iwant to tell you a few words more about it.
The life of an engineer begins with a customer specification. The engineer thoroughly analyzes this specification and quickly presents a block diagram to the boss and the customer, outlining a possible approach. Alternatively, the boss or the marketing team may specify the required topology for the DC-DC converter.
Then comes the research phase. The engineer (or even a junior engineer) frantically searches the internet for application notes, might have discovered some useful resources on the company’s internal network, and promptly updates an Excel spreadsheet with intricate calculations, cell dependencies, and a design curve aimed at maximizing customer satisfaction. A quick LTSpice simulation is performed, and then it's time to order the first prototype board...
The board arrives, and small voltages for powering up the microcontroller, MOSFET drivers, and other components are connected. Once everything is running smoothly, the main transformer is soldered in, and if possible, the mains voltage is slowly increased. If a PFC (Power Factor Correction) is involved, there's usually no chance to gradually ramp up the voltage, so you might use a good DC power supply instead. Then, bang, the switching MOSFET explodes with a loud noise and colleagues fallen off ther chairs.
What now?
First, take a walk and then get back to it. It’s only 10 AM, and there’s still a chance to diagnose the problem and meet the customer's most important asset: The schedule.
After the walk, back to work. Oscilloscope probes are sticking crazy out of the board. For critical and high-speed points, coaxial cables are used to capture the ideal signal, and the voltage is ramped up again... 100V... 200V... and bam, the MOSFET fails again.
Fortunately, the oscilloscope trigger was set well enough that the failure point is captured on screen. But what’s this? The current signal looks fine, gate voltage is okay... no overshoot in the converter voltage... hmmm, okay...
It's already 7 PM. My eyes ache from checking calculations, simulations, and reading theories five times over. One more time, re-solder the MOSFET and measure... Will the prototype board’s trace hold up to the heat of the soldering iron, or will it need to be painstakingly reassembled? Never mind, one more try...
While desoldering the scorched old MOSFET, there’s a sudden click—the thermal pad has torn off. Now it’s clear, and nerves are frayed. Resolving this issue will require another day!
Afterward, there are discussions with senior engineers, sifting through theories, and suffering through sleepless nights dreaming of equations and solutions. Then, suddenly, standing in the break room, talking not even about your own problem but about an issue that occurred years ago with an engineer in company X, you feel a thrilling surge—a big “AHA!” moment. You dash back to the lab, connect the oscilloscope to the discussed point, and... no, that’s not the problem...
Another week passes with the same routine as the previous one, and then, suddenly, you find it:
A tiny, almost microscopic, overlooked solder joint that you had insisted was fine because you had added a pull-up resistor to keep it stable.
You tell a colleague, “If this is the problem, I’ll quit my job..."
and immediately, everything works and makes sense. You can even trace a red thread of the issue from start to finish like an FBI board, with the cold solder joint as the now-known culprit.
The feeling you get is exhilarating—like being a god, though that’s perhaps an exaggeration. Still, it’s close to the feeling of finally answering the question,
“What lies behind it?”
after a long troubleshooting process, learning so much that you couldn’t have acquired through initial research.
This feeling motivates me every time to chase a problem for two weeks straight, keeping the customer's schedule in mind, and sticking with it!
And then comes the field test with the customer, introducing the so-called “dumbest conceivable user,” and you have to accept that some things will remain elusive or become apparent only immediately...
And that’s my life as an engineer, a life I have come to love—both in my hobby and in my profession today!
And I always remember the saying of one of our experienced engineers:
"The things you never think about will kill you in the end"
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