It’s always important to do testing, even on non-SMPS designs, but yes, using a chip like this makes it much easier to get to something that works very quickly. There’s always a lot of opportunities for optimizing the design after the initial attempt if you have the means to do detailed tests.
For example, in this design, I chose a big inductor because of Maxim’s test circuit, but after a crude saturation analysis, it appears that we could use a much smaller one. If space isn’t an issue, you could just stick with 33uH and have very low ripple, but if we’re short on space, I’d order a few smaller inductors and then measure the frequency that the converter decides to run at - if it doesn’t approach the 2MHz limit, it will work just fine.
On the design of the board, you Can use 0603 pads for space, and still be able to use 0805 components, it is a “high density ” pad footprint, but you already knew that
Awesome thread, let’s get this sukka started
Both mattaus and wight had good designs but haven’t heard much about them late
To save board safe would the Atmel ATtiny10 be sufficient, I found a PCB based ZIF socket, might work for programming, just need a good code writer to whip up an awesome UI ; )
For a power cycle only, more simple UI yes it’s probably enough, plus with the attiny10 a 10f322 is a direct swap, same pinout between AVR & PIC. One thing tho is no voltage divider input so no voltage monitoring on the attiny10
With the initial design being for a dual switch light (courui is side switch only but I’ll be installing a tail clicky) it’ll have to be something bigger to run momentary FW.
Ok looking at the Vishay SL42 datasheet (covers the SL43 also) I see that theIF (AV) rating is different from Al to FR4 and that on FR4 its only 4A, is this still safe to use at 8A output on an oshpark board (albeit with a large Cu pour) considering that?
6 Diodes inc Schottky 10A 40V PowerDI™ 5 (I choose this slightly more expensive and higher rated diode for a few reasons, one being this package is smaller than the more common DPAK and also because while its more expensive individually it offers a better bulk discount)
7 AOD510 (exceeds all requirements, has great low RDS(on) and I have a hundred of them)
8 For my use a 12F617 but probably make an ATTiny13A version at the same time for everyone else
10 470ohm 0603's cause again thats what I already have on hand
Good catch, fixed. And while I’m waiting for either one of my Courui’s to get here or for someone to hook me up with measurements, just for S&G’s I thought I’d see if it’d fit in 26mm, definitely not even close!
Very first draft of the very first board, AVR based for you guys (cause if it was for me I’d make everything in PIC). Wish I cold be working on the Courui driver but no one’s yet came threw with measurements or a driver I can borrow…
Notice there is only one remaining air wire (which I cant find, even when I turn off all layers) and it almost passes DRC (only has a couple of clearance errors)!
42mm for TK61. I have some more components to add to the other side including a smart latching FET based switch to kill the buck chip (since it doesn’t have a low power standby mode), that’s what the 2nd e-switch will do, one for power and one as the normal AVR momentary FW input. That will all require major changes, I just needed something to show for what I’ve got in this already so I threw this together.
Sorry C_K, I loaned my Courui to a mate for the night. I should be getting it back tomorrow, so I can give you dimensions in about 24hrs from now if need be.
excerpt from OP in Teardown and Mod Thread of Courui XML2 Aka “Big Head 3x18650 Side-Switch Thrower”. See the bottom of the OP for two pictures of the driver, one of which includes a good view of the driver cavity. The ledge looks pretty meaty, so watch out for that. That’s probably an important measurement to get your hands on.