Try using a smaller footprint FET like the LFPAK56, about half the size and very low Rds-on.
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)!
NICE)!! smash compments, fix silk scrern,but daggum most AWESOME what size driver and what will it go in when you are done?
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.
…So he ‘forgot’ to bring it back in to work today….
If you need other measurements, like shelf width, etc., let me know.
Yes I need everything, I also need the spacing of the cells so I can get that figured out.
Question, will it be possible to drill and tap mounting / ground holes (2 or 3) in the ledge the driver sits on to be able to screw it down? With the series conversion driver orientation will be critical.
This is what I’m working on in the mean time, there are several components missing for a smart latching switch (that will run off a coin cell) that uses a FET to kill power to the MAXUM chip, this will allow both buttons on the TK61 to work as normal, one as power (turn the FET on/off) and the other as the one mode change switch everyone uses for the different AVR momentary FW’s. The ATTiny13A wont control the FET at all, the Li coin cell will power a small iC to handle that part.
As you can see this is version 0.1, there are several issues I see right off the bat so still very far from having anything to order.
Nice job CK!
The inside diameter of the driver tube on my Courui is 34.1mm and the cells are in a 22.2mm circle.
Hope this helps, keep up the good work 
The driver for the Courui has two locating tabs, with corresponding cut-outs in the shelf, which would be the perfect place to drill & tap. ~12 o'clock & 6 o'clock in picture below;
In fact, I will do this to mine when I get it back instead of having the solder blobs there for grounding purposes.
subbed
Hm, I hadent paid attention to the ears, one thing I’ll need to verify is that the cut’s for the tabs are at the same location in every different variation of host. I may have to end up not doing them, since again there’s only gonna be one way the driver can be orientated cause of the cell conversion.
I’ll be getting a couple more Courui’s from the GB deal, so will be able to compare the cut out location. Unfortunately, they probably are a few weeks off yet.
Even with the driver in a fixed position, won’t we have to make sure the battery tube will end up in the same position when screwed on?
edited- changed ‘BG’ to ‘GB’…
In my experience they always end up within one degree every time you tighten them back down, maybe a different location than with the original board but I’m willing to bet it’ll work once we get it figured out, it’ll also probably be different for everyone’s lights.
Hopefully the pictures here give you what you need.
That was my concern.
The 'ears' on the driver are at 90 degrees to the hole for the switch. ( & I'll bet that will be the same for all of them).
:beer:
Very useful, thank you.
One more slightly more in-depth request, could you please remove the tail. remove the Batt- contact plate and then screw the body onto the head (with driver installed) and mark the position of each cell’s + button on the bottom of the driver? (I’ve done this by using a drop of fingernail polish on the button, it’ll transfer leaving you an exact position mark)
I’ll get a picture up of that tonight for you.
I’m guessing that your design is going to have one (or more) separate battery contact points on the base?
The only way I can see that working is if the driver was fixed in the correct orientation for each individual head/tube combination, which would be relatively easy, using the existing cut-outs in the shelf for screw-points.
As requested;
Ive got my circuit designed for the power cutoff using a P-FET, I have selected a large, high enough rated P-FET to be able to supply all the power to the entire driver /load but I’m wondering if I need to do that or if I could use a much smaller rated (and package) FET to ONLY cut power to the MAXUM chip?
That would be ideal, but unfortunately it’s not practical because of the high-side current sense on this chip. If you look at the circuit:
you can see that the chip is measuring sense voltage between the Vin and CSN pins. If you put a FET in front of Vin, you’d have a voltage drop due to the RdsOn, so the voltage the chip measured would be lower than the actual sense voltage, meaning it would skew your current setpoint up, possibly by a quite significant level, and even worse it would be unpredictable due to FET drive differences and Vbat changes.