17mm & 20/26/27mm single-sided DD/FET driver release: A17DD-SO8 / A20DD-SO8 / etc

  • It must be able to withstand the full battery voltage in reverse.
  • Low Vf at around 5mA.

The 2R4 and 3R0 are really pretty dang close. I wouldn't pay extra for the 2R4, but it was available in large quantities when I placed my last order, the 3R0 was not. I've used the 1R0, 2R4, 3R0, and 4R0. Between the 2R4, 3R0, and 4R0 it is hard for me to differentiate between them. The 1R0 may be measurably better with fresh cells, but it is hard to tell. It seems like how hard I'm pushing the battery against the spring seems to make more difference at the top end than the FET used. I haven't tried to measure yet down in the 3.6V-4V range, just wide open with fresh cells.

The one that really stands out as a great performer is the SIR800DP. I think that I would take that over the 0R9 or 1R0 for single cell use because entire curve is shifted to lower voltage, which is what you need when your batteries are getting lower. All of them work awesome at 4V+.

I'm wondering if you would see a greater resistance decrease from simply removing the polarity protection diode than you will from going from a $0.65 to $2 FET. Has anyone measured the gate voltage under load with and without the diode in place?

Thanks for chiming in RMM. I think you hit the nail on the head with this bit:

I haven’t measured the gate voltage. Or if I did I was working on something else and didn’t keep track.

I would not think that you would net more than 0.2v at the gate by removing the polarity protection diode… which should net you an improvement of less than 1mOhm under load with the PSMN3R0-30YLD… not a big gain, but that might put it on par with the PSMN0R9-30YLD. I do not think that removing the diode would put PSMN3R0-30YLD on par with SiR800DP, which is currently cheaper than PSMN0R9-30YLD anyway.

Removing the diode might get PSMN0R9-30YLD on par with SiR800DP on fresh cells, but why would anyone bother? SiR800DP still seems to win in general.

The question is whether it's worth $0.50 extra per driver to go from the 3R0 class to the SIR800DP. With the 6V+ emitters it definitely isn't, but I'm not sure yet for single cell use.

Thanks guys :slight_smile: i don’t know why i so enjoy these kind of discussions, i have really tried to get a grips on how it all functions but when they keep using different scales to describe the same feature & i try to recalculate it to compare the graphs in my mind i always fail :frowning: no matter how hard i try.

Maybe thats why, it is almost a little mysterious to me :smiley: someday maybe someday.

The biggest thing i got from this was that i had almost totally missed that the SIR800DP was seemingly now suddenly (to me ;)) the strongest performer.

And the removal of polarity protection diode “mod” if one could call it that, so SIR800DP+no diode :bigsmile: = max possible performance :bigsmile: + some extra pressure on the spring if possible = even more :smiley:

Just to double check so i understands things right, because i just realized that i totally missed to buy any diodes anyway. the diodes is the “D1 – SOD-323 & SOD-723, assorted” from the OP (i mistakenly thought that was for the with Zener functionality only) can any one give me a good pointer on what to buy.

I got wight’s
It must be able to withstand the full battery voltage in reverse.
Low Vf at around 5mA.

And i saw pilotdog68’s point about easy markings, so i don’t have to measure every time i want to make sure.

I can find SOD-323 at 5v but i haven’t found one with 5mA yet just way above, that makes me think i am not even on the right kind of diode yet.

So what are you who are already building these using?

Is this the correct type?
I have tried to find one but i can’t find one that is in the range of the whole 2,5v-4,3v for single battery use & with a Low Vf at around 5mA
And if try to include a marking also i get even worse hits………

No, that is the wrong type. I did not think to mention it when pilotdog68, but it must be a Schottky diode.

There are carts on page 2 of this thread. Those include an appropriate diode. While there are certainly better options on the market, the ones in those carts are the ones I’ve tested.

me too, it’s a real joy to follow these discussions.

So my next order will be SIR800DP…

cajampa:
http://www.mouser.at/ProductDetail/ON-Semiconductor/NSVR0320MW2T1G/?qs=sGAEpiMZZMtQ8nqTKtFS%2FIMZb%2FvX%2FZJHlCuzGQtxqeU%3D
This looks pretty usable for D1

I’m sure this is answered somewhere but I’m unable to find it atm.

Is the input of the voltage divider connected to Vin or to the output of D1?
Output of D1 would mean voltage monitoring with the Zener mod is not usable because the max input of the divider is the Zener voltage?

EDIT: rtfm - everything is in the 1st post

So this would be appropriate for D1?

http://www.mouser.com/ProductDetail/STMicroelectronics/BAT60JFILM/?qs=sGAEpiMZZMtQ8nqTKtFS%2FDN1hV5GaDZf5Bg1m7lVSCY%3D

Reading the datasheet, vF is about double the vF of the NSR0320. On the other hand its half the price.
Looks appropriate to me.

Sorry for highjacking this thread:
I’m currently fighting one(now 3 of these drivers) to get them running at >4V input.
Maybe some of you can take a look? A17DD Driver does not switch modes

is 0.58v at 1amp an acceptable rating for D1?

The diode doesn’t pass that much current to the mcu.

I know, but that’s the only Vf level that the mouser specs list.

It does seem on the high side. What’s it for? Many of the drivers listed in the Oshpark thread have carts listed or share similar parts lists.

It matches the Vf of a diode that wight recommended but at 1/3 the cost. It sounds high, but it’s in the lower Vf range of the diodes mouser has for sale.

With 3.67V on the driver input (while running) I measured 3.51V at the FET gate full on. At 2.99V I measured 2.833V. This is with the "ultra low vF" diode. It was pretty consistent at around 0.16V difference from input voltage to gate voltage. I need to swap in one of the cheap S4 diodes from the 105Cs and see what kind of drop I get from that.

Hi, these days I tried to study about A17DD-SO8. I find single side design a great feauture. I have some questions though.
How much is cost of this board, compared with classic 17mm fet blf fet driver? Except it’s single side design, does this board have advantages compared with blf fet?

it is zener ready

The cost is pretty much equivalent. It is easier to build and fits in more lights. The performance is equivalent.

Finges: there was already a specific zener mod FET driver. You could also easily modify the earlier revisions as well (but not the v1.0 versions without some modification).

I don’t do Windows. I was looking at cheap Windows laptops to program drivers and wondering what are the minimum requirements to program these and other boards. If you guys could suggest what is needed that would be a big help, thanks.