Wight, have you had a chance to play with any of the LFPAK33 FETs yet? I ordered some and have a few boards almost done with them, but haven't had a chance to try any yet. I put one on the 15mm version of this board and according to NXP it looks like they are pretty much equivalent to the LFPAK56 FETs.
Heh, frankly I haven’t thought any about them, although as you probably realize I have a couple on hand. I haven’t really shopped to see what’s available. Where it fits I feel like Power-SO8 is the ideal footprint since there are so many options available. It’s a very popular package and no one is likely to be unable to source appropriate parts.
That said, when I re-attack buck circuits I’ll be looking hard LFPAK33 and the other 3.3x3.3 MOSFETs. I can see why it’s a good choice for the 15mm layout.
I forgot to mention this: when I ran the CAM job for v009 I ran both the old and the new job and uploaded both to OSH Stencils. Sure enough, both were off. I think it’s just a flawed setup on their end.
As far as I can tell the dual-pwm is working fine.
Moon 2
Low 37
Med 40
with dual-pwm at 38.
Mode spacing appears to be very good set that way. I’ll build another today and post pictures, the first is in a triple XPL 3D Convoy S2 right now.
On this and on some of the DD18 SO8 drivers I am getting a buzzing on the two highest pwm modes, what normally causes that? All of the solder appears solid.
AFAIK the buzzing is something resonating. Tuning your PWM should help eliminate it. Change duty cycles (mode levels), PWM freq, or PWM type (fast/phase correct). The Dual-PWM functionality can split PWM types right in the middle of your mode group if you’d like, that may be able to eliminate the noise at the top end. That’s what’s going on with the “#define FAST_PWM_START”.
Looking forward to pics of your next driver build.
9.6Mhz is right on the ragged edge with a protection diode in place. Atmel’s datasheet shows that up to 10Mhz is OK for 2.7-5.5v, but the diode drops around 0.2v or more. So at 2.9v the ATtiny13A sees 2.7v. There may be other considerations that push you over the edge in certain circumstances.
In other words if it’s possible I’d try and stick to 4.8Mhz rather than 9.6Mhz, just to have all your bases covered all the time.
What offtime values are you using and how much time is it taking to save?
I’m saying that it may malfunction once voltage drops low enough. There will be no damage to the driver, but it’s anybody’s guess what could happen. LVP could fail, that would be my primary concern.
How many seconds does the driver take to save the last used mode?
If I understand correctly, that will change the PWM speed to about 1.2 kHz or 2.4 kHz… which is much easier to see. Even 4.5 kHz bugs me; I can’t not see it strobing unless it’s at least 10 kHz or so.
But if it looks fine to you, then it sounds like you’ve found a solution.