People often bring up that the 10SSU (attiny25v) is 1.8-5.5v but miss the fact that atmel says you need to use 4Mhz max for the 1.8-2.7v range. And none of the current firmwares implement 4Mhz. (4Mhz code)
Aka: the minimum voltage is 2.7v (with the current firmwares) regardless of whether you use attiny25 or attiny25v.
The ATtiny13a runs with 4.8 Mhz and is fast enough for everything, so I don’t see any problem running the 25V with 4 Mhz.
I would like to do some tests with this mcu’s but unfortunately I have only 25_V_ for my breadboard and no 25_V_ in the small package for the driver PCB. Will order some today. Never desoldered this small things, what’s the cleanest and cheapest way to change the mcu on the PCB? I don’t mind if the desoldered one get’s destroyed.
I really wouldn`t be astonished if the problems with the X5/X6 disappear with the right driver and frequency.
I suspect using 4Mhz may very well improve reliability of even the attiny25.
And that means 3 volts from the battery because of the power drop at the schottky diode. At 2.7 volts from the battery the mcu will be at 2.4 volts!
The fuse settings I found in Toykeeper’s bistro code indicate a brown-out detection at 1.8 volts.
Hi,
did you test a MTN 17DDm Driver with Bistro UI under high loads already? I plan using that one with some triples. Now i am confused if the driver will work with high currents.
Regards
Kenjii
I have taken a X5/X6 driver from the group buy and put it in a triple build with warm white 219C leds and a Efest 18500 IMR battery, all resistances minimised (mod post here, #484 in the what did you mod today thread). It runs over 10A with no problem (judged from the light output of 2000+ lumen OTF), but if the tail is removed and replaced with a copper sheet loop to measure the amps with a clamp meter, the bump to moon problem occurs and I can not do an actual measurement.
So I’m not sure what actually happens but 10A seems no problem.
It has been reported that Richards MTN drivers don’t display the same characteristics as the Manker built versions. His board design is different and seems to yield a more robust driver.
I have the Bistro pushing some high output lights with no issues, even have a couple that show full tail amps well up over 12A.
ATtiny25 with or without “V”?
The only 2 readily available samples of Richards FET+1 with 25 MCU I have both have ATTiny25 20SSU components.
I’m not the best to take macro pictures 
MTN17DDm-NUV :
BLF X6 :
Looks like RMM’s new version has a gate-pull-down and something that could be a flyback diode (?).
When it comes to buying a fully assembled and flashed driver, I’d go with RMM any day, no brainer.
khas’s pictures are at:
MTN17DDm-NUV (above)
BLF X6 (below)
if you can’t see them
Thanks hank, well I can see them, I’m just not sure if that’s a flyback diode I’m seeing.
Thanks Sharpie. There are two diodes on RMM’s driver, right? One for polarity protection and the other one? It’s not a Zener for use with two cells, right?
Thanks again Sharpie. Just to make clear, I’m not asking because I want to copy anything. My only intention was to gain a better understanding of that stuff. But I understand your point, after all everything here is public and it’s Richard’s design.
Richard has a Zener diode on the Z1 pad, and a gate resistor as a pull down to lower the shock wave of the FET switching on/off, I am not sure of the value of that small resistor but think it’s very high.
The pic of the X6 driver is the standard Bistro version, with the ATTiny25 20SSU MCU. It’s been said that the 3R030 FET is what helps make it work, a faster switching FET causes issue apparently and this is why the gate pull down resistor is needed.
Chouster, the Zener in this case is merely to smooth the signal to the MCU, if it were for 2 cells the 25V reverse polarity diode would be replaced with a 200 Ohm resistor.
Boy, I've/we've been thru all this stuff already. Yes - 25 vs. 25V - no problems, like Halo pointed out.
If you check Richard's parts kit for his new BLFDD17m v 1.11 driver (mtnelectronics.com v1.11 kit), you'll find he uses a 40-60 K ohm resistor on the FET gate - I've been using 12K with the SIR800DP's and the Tiny85, 85V or 85 - makes no difference. My thinking was the lower the resistor, the less possible impact but I could be totally wrong - I'd trust Richard more on this.
My own opinion is I believe the zener he uses in his design is probably a superior solution to the flakiness we've had with 25/45/85 drivers, probably a better solution than what I've done with extra caps, or what Manker/BangGood did on their 25 based driver, which is using a 12 uF cap, not a 10 uF cap btw.
Little history -- Manker/BangGood had problems getting the driver working, so TK asked me about it. I recommended to TK what I've been doing to get reliability out of the 25/45/85 drivers, boost the 10 uF cap or add a 0.1 uF cap between GRND and VCC of the MCU.
Next thing you know, the driver worked and X5/X6's started shipping with no word back from them what they did. Of course I had to know - it looked like our standard known parts, but I pulled the C1 cap and tested it - it's actually 12 uF, not 10 uF. So, their "fix" was from what I recommended, but instead of going with 20 uf (2 10's in parallel), they apparently got it working with one 12 uF cap.
I published/posted this fact of the 12 uF caps, but didn't get much of a response, so dunno, probably lost in the jungle of topic changes in the big thread... Pretty sure TK is aware of this now - think she responded.
I would definitely trust Richard's designs and parts he uses, and superior tracing layouts. If you look at resistors, caps, etc. on any of the popular major source sites like Mouser or Digikey, you will find tighter tolerances and better spec'd parts generally cost more. 1% resistor will typically be more $$$ than 5% resistors. You should see what difference it makes on current sensor resistors, where the better ones costs dollars, not pennies. I'd trust Richard is buying the better more reliable parts from known sources, like Mouser, as opposed to China sources where they buy the cheapest on the market, which will probably be the worse parts as well.
I bought these recently: http://www.mouser.com/Search/ProductDetail.aspx?R=ERA-6AEB6983Vvirtualkey66720000virtualkey667-ERA-6AEB6983V, and in qty 10 they cost 25 cents each, which is very high for a resistor, but a tolerance of 0.1% is incredibly good.
Thanks Tom E, that’s a great summing-up.
Krono put it this way a while back:
Thanks for all the information!
I understand now ATtiny25 works flawlessly at high currents if attached to a well designed board in combination with selected components. I also see at least on reason to use ATtiny25 and not the 25V - it’s half the price. Nevertheless I still believe the ATtiny25 is used out of specs in low batt situations - which the lumen enthusiasts here (including me) will probably never face. Ok for hot rods used by experienced persons, but perhaps not for the average user participating in the group buys.
So here for now my last question: in addition to the price difference - has there been any technical reason to prefer the ATtiny25 over the 25V?
Again, this is correct - straight from the Atmel spec:
Speed Grade
– ATtiny25V/45V/85V: 0 – 4 MHz @ 1.8 - 5.5V, 0 - 10 MHz @ 2.7 - 5.5V
– ATtiny25/45/85: 0 – 10 MHz @ 2.7 - 5.5V, 0 - 20 MHz @ 4.5 - 5.5V
So what his means, regardless of which model of the 25 is used, at 10 Mhz 8 Mhz there is no difference, and TK's Bistro and the couple of firmware versions I've ported all run at 10 Mhz 8 Mhz. here it is, on page 1: http://www.atmel.com/images/atmel-2586-avr-8-bit-microcontroller-attiny25-attiny45-attiny85_datasheet.pdf. Also on page 163, section 21.3 shows the diagrams of max frequency vs. VCC, confirming at 10 Mhz 8 Mhz on either the 25 or 25V, min safe operating voltage is 2.7V.
So at 10 Mhz 8 Mhz, there's really no difference between the 25 and 25V. I've also used both - no differences. Much more important when ordering, is to get the proper package to fit the pinouts of the pad you are using on the board. Mostly we use the same pinout pads as our standard 13A, which is S8S1 (refer to page 204 of the spec).
Oopsie! Meant 8 Mhz, not 10....