At 4S you would need to not use the 7135’s and only use the FET.
There are some 12V capable 7135 replacements that could work with 4S setups now but no one has tested them that I know of yet.
OK, thanks.
BTW, TC (maybe with minor adjustments) could regulate 4s lights up to its thermal limits, right?
Yes, the Texas Commander could run up to 4S but you would be limited to pretty low currents due to the high wattage it would have to dissipate.
The LD-4 has a 4 layer PCB that offers better cooling and thus higher limits but if you really want good 4S linear regulation I saw that LED4Power is not selling an mcpcb with the FET on it as well like I suggested back in the Texas Commander thread.
That solves the heat issue and allows you to run basically as much power as you want. It is possible his mcpcb would work with the TC but it has not been tested.
Yeah, I would gladly use LD-4, but:
- it is 17 mm only
- it doesn’t support e-switch
- it doesn’t have open-source UI, which I can customize to my whim
In that case the TC is only in 17mm as well so that won’t help you I suppose.
The TA series will work but is limited to FET PWM control at 4S. That is unless those 12V 7135 replacements work. If so then they would be an option.
TC is open source, so I can figure out how to design a PCB and with help from the great BLF members make it up to size.
True, it would not be hard to extend it to larger sizes, it was quite hard to shrink it down to 17mm though lol.
In particular, I’d like to see some fairly cheap and fairly good way of doing Q8 with XHP35 HI. FET-only is not a good option.
TA with 7135-like chips would work and be able to get good efficiency up to fairly high outputs. It doesn’t exist, no one has tried the necessary components and shared the results publicly.
TC would be probably more thermally limited, so have lower regulated output. But it would have better efficiency at low modes and maybe lower moonlight. It doesn’t exist either, but all the parts except for PCB are available. It is at the concept stage of development though.
I view both options as roughly equally good (assuming 7135-like chips work well for our purposes) and roughly equally distant. But different. And, assuming the price is similar, I’d like TC more.
Buck or boost drivers would work (assuming they are not too high), but probably cost more and be less hot-roddy (which is not bad by itself).
The FET actually works pretty well with the XHP35. Particularly with 4 of them in parallel it should work pretty good, be it without true regulation.
I have a few lights running xhp35’s with the TA driver and they all work good. You might need to limit the max duty but this is easy, although with 4 LED’s you should be ok without it.
A buck driver would be the next option, it is possible but not easy. The GT driver for example would handle up to 5A. It is possible to make a bigger driver to handle more as well, 10A should be doable without too much hassle. Which would be perfect for 4 xhp35’s.
Although with how the driver is mounted in the Q8 getting the cells to line up properly with a 4S cell setup could be difficult.
I don't see anything stopping most of these features. Bistro-HD with OTSM already works on your boards, just have to change the components as described there. Lexel has been making some up. Sure you could do it with cheaper caps with a newer low-power chip. Ok, but come on designing a new board just to save $1.00? It wll require more motivation than that. It also includes what I would call an improved thermal protection. There's no reason your boards can't have thermal regulation either, the coding is just hard. TK seems to have something that works pretty well. I see no reason it couldn't get added to HD either. TK also has clikcy ramping now and I see no reason that shouldn't work on your boards. Current regulation, again, if you mean the software voltage feedback stuff, that's still possible exactly as is. I almost started into it again recently, but I find it hard to get that excited about it. Plus I did some of the groundwork on voltage curves and lost it, and got frustrated. Flash programming, well, I'm not sure on that one, might need different circuitry. I'd be happy just to have rear access pins for flasshing with one of the QFN chips.
The nice thing adding a feature to HD is you automatically get it added to any compatible board you want just by adding the #define to a config for it, which was kind of the idea of HD. Even if you #define out the entire UI (most of the code) and #define in a new one, like a ramping one, you still get to re-use battcheck and voltage calibration and the layout definitions, so again, you get to apply it to all compatible boards. Although the need for pretty different ADC read methods adds tension to merging some codes.
It's unfortunately a bit hard (but not impossible) to imagine all frmware features merging into one code base like that because the need for inlining functions to save space tends to complicate code organization some. That is a place where small chips with more memory help. I don't really imagine stuff ever becoming truly that unified though. It's just not how people work.
Anyway, TA, your Q8 boards you mentioned somewhere back that the indicator should be wired to the divider pin? Is that right? Then the idea to use "internal" voltage sensing?
It seems like that should work. I may add an HD config for it, since I'm playing with Q8 eswitch configs anyway.
[quote=Mike C]
Ages old post, and probably irrelevant now, but yes, using the same pin for divider and pin-check is exactly how I did it in HD. But you have to keep the LVP voltage high and for 1S there is no reference voltage high enough. So for 1S you use "internal" voltage read. For more than 1S you use the Vcc pin driven by the LDO as the high reference voltage, and then just keep the battery sense voltage between 0.6Vcc and Vcc, which happens to be just how much range you need, and just how much range you're allowed by pin change specs before risking a low-pin detection. Exact details are in the manual.
Well the biggest thing I want to change with any new versions is updating to the latest MCU’s like the 1616 or 1617. The other features come with them.
HD can indeed be used with the boards as is (although I still have yet to see a clearly laid out change list which is why it is not in the OP).
I simply see no reason to make any changes to these drivers until said changes would net a worthwhile improvement. In this case, that would be the newer MCU’s and all the features they unlock (both internally and in the fact they are a fraction of the size of what we are using now).
The clearly laid out change is in the manual. But many of those other feature don't come with the new chips. Many are already available just fine, other than the flashing and extra memory. I'll go grab a quote from the manual for you for the parts change list for 1S and multi-S.
Here's it is. >1S haven't really been tested yet. I think lexel is offering them up now, but I'm not sure he's built any yet. So no feedback on any typos on that yet.
VIII.1a Parts and build for tested TAv1 board for 1S
MCU:
It's required to have BODS support for the mcu (see theory below). From page 36
of the manual this requires:
• ATtiny25, revision E, and newer
• ATtiny45, revision D, and newer
• ATtiny85, revision C, and newer
The spec for OTSM also requires V version (10Mhz, low voltage version) chips.
You might get by without it, but it won't work as well and may cause
corruption.
Unfortunately most ATtiny 85s reported off the shelf have been revion B, for
the past many years even. They don't work. So far Attiny25, attiny25V,
attiny45 and attiny45 v's where reports exist on this, have been of recent
enough version. Of course attiny25V is available in the smaller footprint and
fits 17mm TAv1 boards. At the time of this writing all HD features including
OTSM can fit on an attiny25.
Diode part number: RB751V40T1G
http://www.onsemi.com/pub/Collateral/RB751V40T1-D.PDF(link is external)
This is the MCU protection diode. It isolates voltage from the C2 cap that
powers the MCU while input power is down. It was chosen for its low leakage
even at high temperatures. Leakage below 1 or 2 uA is probably fine.
C2 cap (powers MCU during off time, quality counts here)
Cap part number: 298D476X0010P2T
http://www.vishay.com/docs/40065/298d298w.pdf(link is external)
This cap was chosen to get the most capacitance in an 0805 possible and because
Tantalum does not suffer from DC bias de-rating or temperature fluctuation.
Capacitance this high (47uF) in an 0805 are all low voltage. For Ceramic if
the DC offset is more than about 1/3 of the rated voltage the capacitance
starts to drop, some times a bunch. This cap does have a large tolerance
though unfortunately.
Voltage divider:
Tested with R1 of 1K and R2 of 3.3K (1%), R1 should be no more than about 1/3 of R2,
but this ratio should be ideal for OTSM performance in a 1S light (but only in
a 1S light). Lower values can improve OTSM performance, at the expense of
higher mood mode drain. If you use lower quality caps or diode, you can try to
add a bleeder of about 500ohm to gain a little advantage on off time, not much.
OTC:
None, unpopulated.
C1: 1uF
VIII.1b Parts and build for TAv1 board for LDO (2S, 3S etc)
Quick version:
See section VIII.1a for mcu, cap and diode selection.
Place the diode on the R7 resistor pad with the anode (+ side) pointing away
from C2. No OTC cap is needed. Use the following divider resistors:
R1 R2
2S: 1780 2210
3S: 2250 1500
4S: 2870 1100
No bleeder. That's it.
So I do need to review what lexel said about his experience with LDO without a diode. I think he said it worked on your small boards. On the large board, we added the diode in place of R7. I'll review it. That part should indeed get updated now.
Ok, so with the 17mm board he said he "got it working" without the diode. He said you use a different LDO on the 22mm board. For that one the solution was to replace R7 with my stated diode as in the post above. It could only possibly help in the 17mm board too though. So I think there's no change to the above instructions (he just hadn't seen them).
Also Lexel said this:
He's not exactly right. The Vishay has much more detailed specs. It lists half the max leakage current (and it's at levels where it could matter) and lists much more explicit temperature derating curves. Still, his cheaper one might work ok, I'm just not ready to call it my recommendation, but you could list it as an alternative budget option.
Updated with bolds for the impatient reader.
Now the shortened OP-like version, just the bolds:
All builds:
• ATtiny25V, revision E, and newer (all known recent attiny25V's) or
• ATtiny45V, revision D, and newer (all known recent attiny45V's) or
• ATtiny85V, revision C, and newer (none have ever been seen, skip the attiny85)
Schottky Diode part number: RB751V40T1G
http://www.onsemi.com/pub/Collateral/RB751V40T1-D.PDF(link is external)
For alternatives, leakage should be below about 1 or 2 uA when hot.
C2 cap (powers MCU during off time, quality counts here)
Cap part number: 298D476X0010P2T
http://www.vishay.com/docs/40065/298d298w.pdf(link is external)
For alternatives, compare leakage and temp derating. Beware DC performance of ceramic.
OTC: None, unpopulated.
C1: 1uF
1S builds:
Voltage divider:
R1 of 1K and R2 of 3.3K (1%),
Any similar values with R1< 1/3 of R2 will work.
2S, 3S, 4S builds:
the diode above goes on the R7 resistor pad with the anode (+ side) pointing away
from C2.
R1 R2
2S: 1780 2210
3S: 2250 1500
4S: 2870 1100
Note these only work with a 5.0 V LDO.
No bleeder. That's it.
Of course 4S is dangerous anyway and requires a custom FET-only firmware. I should make that.
Much better, this is something that a layman can actually understand which is the target of the TA series, make it assessable to anyone that wants to give it a try.
Which is why I go to such great lengths to for example allow a single HEX file to be all that 95% of people need and most people to never have to touch the code.
Is there a one size fits all Bistro HD firmware HEX download to go with these instructions? I will need to add that to the OP to make HD “official”
It's important that those 2S 3S and 4S resistors can only be used with a 5V LDO. If you use a different LDO, you need different resistors. I think I previously checked that you call out 5.0V LDOs?
Also notice I update "Any values of with R1 < 1/3 R2"... to any "similar" values with...