Here’s a driver I’ve been wanting to do for a long time and never did. It’s based on the Chinese QX5241 buck controller, same controller used in the old DX SKU 20330 and the new-version DRY driver. As far as I know it’s also the same one used for a bunch of other drivers such as one IOS previously carried and this 5A one from LCK-LED as well as a few others.
A Nanjg 105c and a new-version DRY driver together will contain nearly all the needed components to assemble this driver. It requires the torroid from the new-version DRY driver, so that makes this driver quite tall, the top of the torroid is about 11mm above the bottom of the PCB. This driver requires a 5mm diameter by >2.4mm tall spring or spacer due to the large diode on the bottom. As you can see, the combined height of the board may be 14-15mm thick overall. I haven’t calculated sense resistors, but since I only put a single 1206-sized pad you’ll probably need to pick that out for a special order.
LED+ connects to one leg of the torroid, the other leg attaches to the via next to the Q1 marking. LED connects to the body of the FET. I forgot to add some 1μF capacitors on the VIN and VCC lines for the two microchips respectively. I’ll need to go back and add those. We may be able to cram in a second 1206-sized sense resistor.-
are those standard 0603 or 0805 solder pads for the resistors or capacitors? Not sure if they just look really close together to me or not. Most cool though, is this a buck type setup? ATtiny driven?
Really? Why? Only the SM5241 datasheet shows 47uF, the QX5241 shows 1uF and the LY5241 datasheet doesn’t seem to mention it. To me it doesn’t seem like you’d need that much capacitance just to smooth out the 5mA the chip draws.
They are 0805 pads. It’s a buck setup. I used the standard pin configuration for the ATtiny13a w/ one of our normal firmwares. This is for clicky only. It’s going to look at little more packed in a minute or two here.
What is the voltage range of that driver? If it can buck 3x in series down to run a single emitter…I have a home depot defiant I can upgrade to a 26650 rather than C cell
I expect this driver to perform like a less-efficient new-version DRY driver. The voltage range should be something like 2-3s or 2-4s. Remember, this thing will be huge with the torroid on top.
I have revised the driver to add 0805 caps for both Vin on the QX5241 and Vcc on the ATtiny. I also added a second sense resistor in parallel. I did not do a very clean job and I will probably improve the layout in the C1/R4/R1 area at least, as well as some unattractive traces.
Yea, I think they look off too. 0805 should have a pad separation around 0.7mm. Oshpark renders boards using tStop for the copper areas instead of Top for some reason. Makes all pads look 3mil larger in the renders.
Are you using the oshpark DRC? The default eagle DRC has 4mil mask instead of 3.
I don’t know, even if its the eagle default 4mil, pads look off. Course I didn’t sleep last night so my eyes might be off.
I didn’t realize that I could adjust that - I see it now. Thanks. I had it set to the default, 4mil. I’m using the Eagle R0805 package for the divider resistors and C0805 for the caps.
WarHawk-AVG, please read the thread. It’s a buck driver and will go at least low enough for a single white emitter. Results are posted in the short thread I linked. The driver will not operate on a single lithium ion cell. The links in the OP were meant to answer this question.
Thanks, let’s hope we get something useful out of this thing. I’m feeling pretty good based on the lineage (all the other successful drivers based on this controller). The only thing that I’m concerned about is how big an efficiency hit we take from eliminating the weird dual-FET setup I mention in the OP. It’s not a synchronous buck configuration, so I really don’t understand what those other designs are doing with the second FET.
At ~$2.50/each in China I figure that’s not much better than the new-version DRY driver. Has anyone seen these drivers around on AliExpress or eBay for a better shipped price? I see them on eBay for crazy prices (>$10!!), but no decent prices.