4 ms·

How does one learn to build such things? Most would say school, but I imagine there are particularly good reads out there that are more helpful to those driven

How does one learn to build such things? Most would say school, but I imagine there are particularly good reads out there that are more helpful to those driven enough to be autodidacts. Thank you for such an excellent and digestible article. Such a pleasure to read.

kens 5y ago
I don't know how to build them, just take them apart :-) But seriously, there are a lot of books on switching power supply design. E.g. Fundamentals of Power Supply Design by Mammano, who is "the father of the PWM controller IC industry".
- andrewmcwatters 5y ago
  Very cool! Thank you!
- seltzered_ 5y ago
  Huh, that's a new one. I worked in the space and Erickson and Maksimovic - Fundamentals Of Power Electronics (along with the courses taught at UC Boulder) was one many centered around. In many cases most of the power engineers I worked with just sorta had a feel for things and relied on simulation tools (LTSpice / SwitcherCAD).
cogman10 5y ago
For something as basic as a charger, an intro to electronics course/book is probably good enough. There's more than enough youtube videos out there about bridge rectifiers and the like. The charge circuitry here isn't anything too special.
- andrewmcwatters 5y ago
  I imagine then that some of the more claimed sophisticated elements come from multidisciplinary backgrounds like having experience with electronics in noise-sensitive circuitry.
- kens 5y ago
  It's easy to make a linear power supply, but a switching power supply like a charger has a lot of complications. Among other things, the layout of the board matters a lot due to the high frequencies involved. I'll point out the the application note on this controller chip is 34 pages long. https://www.st.com/resource/en/application_note/an1326-l6565-quasiresonant-controller-stmicroelectronics.pdf https://www.st.com/resource/en/application_note/an1326-l6565...
  - cogman10 5y ago
    Certainly. My point was more that the basics are pretty readily covered in intro electronics courses. Heck, throw in a low pass filter or two and you end up with a lot of the same required knowledge to make a switching power supply. I agree you won't be able to make an apple quality device, it'd just be enough info to understand how one is working (Without taking into account things like line noise impact on wiring).
- lmilcin 5y ago
  Far from it. Chargers are actually very complex and demanding design tasks with a lot of interesting* fault modes. (* assuming you like small fires and exploding devices) Just because you can make it work doesn't mean it is safe. Good charging circuit will be designed to behave correctly if any of the components fail. Even a simple battery charger can easily cause fire. The usual advice to amateurs is to stay away from charging circuits and switching power supplies. And reuse existing circuits in their designs. There is a lot of complete charging circuits and power supplies made to be included in designs.
  - dontcare123 5y ago
    This isn't an actual charger though, just a basic off the shelf switching power supply, low power AC -> 5V DC. The actual battery charger chip is on the phone (which again, will use a ready made BMS IC, so not really complicated either, all the smarts are already done). There's some things to consider when laying out a switcher (keep loop areas small, keep sensitive lines from noise ones, etc), but it's not that complicated, and once you've done a few of them, it becomes routine. And of course to pass safety standards there are clearance and creepage rules and EMI/EMC to keep in mind. Any junior level EE/hobbyist with a few years of tinkering should be able to put this together.

kens 5y ago

I don't know how to build them, just take them apart :-) But seriously, there are a lot of books on switching power supply design. E.g. Fundamentals of Power Supply Design by Mammano, who is "the father of the PWM controller IC industry".

andrewmcwatters 5y ago
Very cool! Thank you!
seltzered_ 5y ago
Huh, that's a new one. I worked in the space and Erickson and Maksimovic - Fundamentals Of Power Electronics (along with the courses taught at UC Boulder) was one many centered around. In many cases most of the power engineers I worked with just sorta had a feel for things and relied on simulation tools (LTSpice / SwitcherCAD).

cogman10 5y ago

For something as basic as a charger, an intro to electronics course/book is probably good enough. There's more than enough youtube videos out there about bridge rectifiers and the like. The charge circuitry here isn't anything too special.

andrewmcwatters 5y ago
I imagine then that some of the more claimed sophisticated elements come from multidisciplinary backgrounds like having experience with electronics in noise-sensitive circuitry.
kens 5y ago
It's easy to make a linear power supply, but a switching power supply like a charger has a lot of complications. Among other things, the layout of the board matters a lot due to the high frequencies involved. I'll point out the the application note on this controller chip is 34 pages long. https://www.st.com/resource/en/application_note/an1326-l6565-quasiresonant-controller-stmicroelectronics.pdf https://www.st.com/resource/en/application_note/an1326-l6565...
- cogman10 5y ago
  Certainly. My point was more that the basics are pretty readily covered in intro electronics courses. Heck, throw in a low pass filter or two and you end up with a lot of the same required knowledge to make a switching power supply. I agree you won't be able to make an apple quality device, it'd just be enough info to understand how one is working (Without taking into account things like line noise impact on wiring).
lmilcin 5y ago
Far from it. Chargers are actually very complex and demanding design tasks with a lot of interesting* fault modes. (* assuming you like small fires and exploding devices) Just because you can make it work doesn't mean it is safe. Good charging circuit will be designed to behave correctly if any of the components fail. Even a simple battery charger can easily cause fire. The usual advice to amateurs is to stay away from charging circuits and switching power supplies. And reuse existing circuits in their designs. There is a lot of complete charging circuits and power supplies made to be included in designs.
- dontcare123 5y ago
  This isn't an actual charger though, just a basic off the shelf switching power supply, low power AC -> 5V DC. The actual battery charger chip is on the phone (which again, will use a ready made BMS IC, so not really complicated either, all the smarts are already done). There's some things to consider when laying out a switcher (keep loop areas small, keep sensitive lines from noise ones, etc), but it's not that complicated, and once you've done a few of them, it becomes routine. And of course to pass safety standards there are clearance and creepage rules and EMI/EMC to keep in mind. Any junior level EE/hobbyist with a few years of tinkering should be able to put this together.