thefreeman
January 11, 2023, 3:22pm
368
thefreeman:
Well there are several points that makes it more complicated :
it’s double sided so the setup fee is significantly higher, increasing the price per driver in a small batch. Because it would be produced by a fab I could use 0402 passives to save space but that wouldn’t be enough to make it one sided.
for the FW3X, since it’s a boost driver, it would be configured to 9Vout (3 LEDs in series), and the MCPCB would have to be modified to 3S like I’ve done several times on different MCPCBs, but are people willing to do that ? That may decrease the number of people interested in the driver.
physically it’s the same driver in the FW1A, potentionally increasing the demand, but then it would be different Vout/Iout variants, which require a couple of different resistor values. For example 6Vout for B35AM and XHP50, 12Vout for XHP35, technically there is the B35AR (12V) but the availability is not as good, and the XHP50 can be wired in 12V with adequate MCPCB, the problem is that they are often non DTP, or if they are DTP the middle connection goes through the middle pad, shorted to ground, meaning shorted to batt- , it’s a problem that people tend to not be aware of and end up with a non functioning modded light.
because the driver cavity is only ~2.5mm, the inductor choices are only XAL6020 or XGL6020, both of which can’t be sourced with JLC, which I considered as 1st option since they have the lowest setup fees. I would have to reflow the inductor myself.
So that’s why I would prefer to go with a single sided driver for a first production batch, a buck driver would have only one configuration, which would be simpler.
So I’ve been working on making it production ready :
now single sided for lower assembly setup fee, the FWxA having 20mm clearance I used BST21 as base, a 6024 inductor instead of 7030 and a few 0402 passives to shrink it to 20mm
for the different output variants (6V5A, 9V3.33A, 12V2.5A) I left the resistors to be changed as 0603 for easier swapping.
I used a much less costly inductor that still has very good characteristics, only very slightly higher DCR (8-9.6mΩ instead of 6.8-8mΩ for XGL6020)
And efficiency measurements :
1 Thank
