519A vs B35AM in S21A

[manithree]

@Nyr

While the B35AM S21A might me better on paper, it had an important problem: some of them were smoking when pushed at 100%.

This was addressed by changing the maximum current from 3A to 2.2A in the drivers which are being shipped now, so it is important to have this in mind.

The B35AM may seem like a slightly better choice, but the output is now lower than it was in the initial design and reviews, and has a thermal design problem which was addressed in the only practical way possible, using a workaround and not addressing the root cause.

This is why, for my S21A order, I decided to purchase the 519A option even if I would have preferred to try the B35AM.

Nichia specifies 1.4A as the max current, so I’m not terribly concerned that Simon overdid it in his hot-rodding by 700 ma initially (Simon’s message says he dropped it to 2.3A). The 3V 519A tops out at 5A, so that’s really a tiny difference. I’m more interested in efficiency than starting fires, anyway, and my post-April S21A is very bright enough.