The AX2002 is safe up to 25 volts. Please do not cripple the power voltage to other chips with a bunch of diodes so the AX2002 can send them a voltage high enough to damage them.

There is NO negative 12 volts! Why am I designing for negative 12 volts?
Because that's what you said in post #3, "I need to take a negative 12V modulation signal and convert it to a positive".
That's why schematics were invented. Words are a miserable way to describe circuits. (That's your lesson for today.)

OK. This being a flashlight circuit which uses WAY more power than any switching logic, I am going to design more for noise immunity than microscopic power savings. Oh. I just did. Rearrange a couple of grounds and we're good to go.

LOL sorry about that, like I said im still green at this. Im an advanced 'tinkerer' and did not realize the slip in terminology. Just got home picked up some 2n3906's. Im going to get it on the breadboard after dinner and will report back on the results.

Thanks again, appreciate your time and effort in helping me with this

 

Thanks again, appreciate your time and effort in helping me with this

That's what the, "like" button is for.
MrChips is hot on my trail and I want to stay ahead of him in the, "like" department.
For this much work, I feel I deserve some clicks.

 

That's what the, "like" button is for.
MrChips is hot on my trail and I want to stay ahead of him in the, "like" department.
For this much work, I feel I deserve some clicks.

You're awesome my man! Let me buy you an e-beer

Got run down with the flu but finally got this on the breadboard... Works perfectly.
The only issue encountered is the voltage to the little 3mode PCB. It shuts off around 9v perhaps with a protection. The IC doesn't get hot, no parts pop and when I roll back the voltage it comes right back on. 8.4 seems to be its comfy upper limit. I put 6 diodes in series with its positive and it will go just over 13v. The interesting part is with those diodes it also increases the minimum voltage required. The driver shuts off at 6v. By adding another diode or 2 the driver would operate safely within the ranges that are safe for the li-ion cells. Not sure if I want to put a voltage reg in there, the diodes have become a bonus.

My only question is if there is a negative impact on the circuit here?

 

My only question is if there is a negative impact on the circuit here?

I spoke my concern in post #20. If the 3 mode chip does not have any inputs higher than its positive supply voltage, it will be OK. Same goes for most ICs. They believe their world is between Vcc and ground. Any voltage outside that range appears to be an alien invader*.

*In American TV News that would be a, "terror threat crisis".

 

I spoke my concern in post #20. If the 3 mode chip does not have any inputs higher than its positive supply voltage, it will be OK. Same goes for most ICs. They believe their world is between Vcc and ground. Any voltage outside that range appears to be an alien invader*.

*In American TV News that would be a, "terror threat crisis".

I read that post, but dont quite understand. In this case the lower voltage IC is sending out the signal to the ax2002. Where is the potential for a higher voltage to hit the mode IC? The diodes I used are set given the maximum supply voltage which will not be exceeded, so im assuming some sort of spike could come back from the EN pin? If this is the case, would another diode in line with the EN pin cover this potential issue?

I like the diode setup because the batteries will not be able to over discharge. Im running 3x IMR 26650 cells for this light, so this added protection is a welcome thing..

 

In this case the lower voltage IC is sending out the signal to the ax2002. Where is the potential for a higher voltage to hit the mode IC?

You just answered your own question. The lower voltage IC doesn't have a higher voltage to send. I wanted you to check that. You did.

 

You just answered your own question. The lower voltage IC doesn't have a higher voltage to send. I wanted you to check that. You did.

So I have been working with this circuit and have it tied to 4 of the ax2002 driver boards. The 3 mode PCB controls all 4 drivers but
I keep getting an anomaly where the 3 mode PCB will switch from the low power mode into high by itself.

I thought to try a cap across the EN pin to ground and this seems to remove some of the flicker, but eventually the low
mode will switch into high with no interruption to the power.

Im assuming that there is some sort of interference between the 4 drivers causing this. I have changed out the 3906 with
a new one, as well swapped out the 3 mode board with a new one in case it was a glitch from these parts. It still
happens though.

Is there anything I can try to fix this issue?

 

No worries, solved it with a 15k resistor from EN pin to ground. The EN pin on these chips detect a very weak signal.