That seller seems to have disappeared entirely. Maybe later those will show back up along with their other items?
As to your question - It looks to me that the 70N03 is not as good as the 70N02. 0.0081 Ohms at VGS = 4.5v is not as good as 0.0053 Ohms at VGS = 4.5 V. The Digikey link seems to be better than the 70N02 though, it has 0.0032 Ohms at VGS = 4.5v. I think all of those values are acceptable though, really.
The method for rating continuous drain current for the datasheets I looked at (“NTB75N03R, NTP75N03R” vs “SUD70N02-03P”) seemed to be different. To me it seems that continuous drain current is close enough. Voltages look OK. As I said, RDS (on) seems higher but acceptable. I don’t see a problem with using the 70N03.
0.0081 Ohms at VGS = 4.5v is not as good as 0.0053 Ohms at VGS = 4.5 V…That’s almost inconsequential (I believe…heck that .003 ohm might cause it to heat up 2x as fast for all I know)…sure it’s more but it’s a “viable” replacement until the 70N02 come out…as long as everything else is the same
I suppose between the 70N03 and 70N02 is a difference of like 0.02 vDrop at 8 Amps. 8 Amps is a drive level I arbitrarily chose, vDrop will be lower at lower current levels. Since it’s direct drive, vDrop in the entire power supply chain (everything, springs, body tube, driver, etc) has an effect on the Vf available at the emitter. The lower the voltage you can supply to the LED the lower the current you can supply to the LED.
8 A x 0.0081 Ohms = 0.0648 volts
8 A x 0.0053 Ohms = 0.0424 volts
8 A x 0.0032 Ohms = 0.0256 volts
At 4 amps the difference is about half of that. This is not a big deal, but will have a measurable effect. You should end up seeing a difference of 0.01-0.1A between the 70N02 and 70N03 depending on what you are doing with them.
I don’t disagree. Clearly for direct drive lights all resistance including wire, spring, body, cell contact area, etc is important. For current regulated lights resistance is not as big a deal in terms of maximum brightness, but still affects other performance aspects.
OTOH the AOD510 are better than either of the others and cost about the same. Why not use them?
Just did a search and the 70n02 still shows up but from a different seller. Until I use them up I’ll stick with the Lfpak56 since it fits more easily on a 105c than the vishay. I don’t do nearly as many mods as others so they should last awhile.
I have a question in my mind that when you guys are finding the low Ron FET, did you consider the low on Vgs of the FET is also a very important criteria for a single li-ion cell driver?
Most of the high power FETs show their Ron at 4.5Vgs and 10Vgs. I am not sure how many Vgs the attiny13A can provide to the FET but obviously under 4.5V. I doubt that the FET can be fully turned on. Low Vgs FET can be fully turned on at 2.5V or even 1.8V.
I haven't caught up yet with the last 100(!) or so posts, but I tried the AOD510 and... the other one, both of them were flaky changing modes using the same known good gate&pulldown resistors as with the Vishay 70N02, so I didn't bother trying to get any current measurements for comparison.
It (both of them, really) acted the same as the early 70N02/17DD weirdness before the gate/pulldown resistors were added. It might just need different values there, but I didn't have time (and, I have like 150 of the 70N02s).
Sometimes changes mode correctly, sometimes jumps two modes instead of one, sometimes hangs up, sometimes goes into some weird alien-Morse-code thing (dim-bright-BRIGHT!-off-BRIGHT!midlowbright-dim-off... etc.).
Chris are you able to post a short video showing the issue? It sounds like what I have but not sure. Also is this with a clicky or momentary setup that gives you issues (or it doesnt matter, it does it with both randomly)?
The biggest similar issue I’ve had is when I tried to use a stock FET I pulled out of an M6, it cleared up when I swapped it out for a 70N02 however I know the M6 FET’s work when left on their own board but controlled by a ATTiny13A on a piggy backed board, strange…
I had similar erratic behavior with both the irlm 2502 and lfpak 56 when using them without the gate resistor and above a certain current level. The gate resistor resolved this in both cases. It may be something to do with board geometry or who knows what since as far as I’ve heard it varies from board to board or FET to FET.
