Newbie needs help to choose driver

Flashlight Modding and DIY Parts
1

Hi,

I need some help to choose led drivers. I have been reading datasheets and forums to collect info, but now I’m a bit confused.

I’m working on a canister dive light prototype. I will make two different light head, one with xhp70 6 volts and one with xm-l2.
I will use single leds, the battery pack is 2s4p or 2s5p 18650 li-ion.
I will use a piezzo switch. It has a separate control pcb. It works like a simple on/off toggle switch, So the led driver is not always connected to the battery pack.

My requirements:

- I don’t need low voltage protection, I have a separate circuit in the battery pack

- I need 3 modes, 25, 50 and 100% (can be different)

- memory (optional, not essential)

- robust reliable design

  • small size ( 20-25mm diameter preferred)

I think I should choose a buck driver for the xm-l2 and a FET/DD for the xhp70 6v, but I’m not sure which one to select.

2

You definitely need a buck driver for the XML setup, I know that the MTN max series from mtnelectronics.com are a good buck drivers.
They also have Fet (dd) driver. Both with the requirements you want.

This one for example:

And this one:

For the XHP70 you could also use the LD-3 driver:
LD-3: LD-2 on vitaminS (2-12Amps CC with configurable UI).

3

Thank you for the suggestion.

But the FET + 7135 Driver - 22mm - MTN-22DDm input voltage range is 2.5-4.35, and I have a 2s battery pack (8,4V fully charged).

The 22mm MTN-MAX 1A-6A Buck Driver - 5V-18V seems to be a good choice for the xm-l2. Can I use it for the xhp70 also?

According to the data sheet the LD-3 can be used only with momentary switches, but I will use a piezzo switch latch circuit.

4

The Fet driver can be zener modded. That means it can except a 2s input. There are also fet drivers with a ldo voltage regulator, also for 2s input.
The Texas avenger driver is also an option.

The MTN buck driver can also be used with the XHP70, but since the voltage difference is smaller it can drop out of regulation. However don’t think its a real problem.
Buck drivers require an specific amount of voltage overhead, lets say 1 volt. That means to drive a 6 volt led it requires ar least a 7 volt input. If the input drops below that it falls out of regulation.
I believe that the MTN series only needs around 0.5 volts (not 100% sure), so it should be good.

The LD-3 can only work with clicky switches, that means click for on and click for off. No momentary.
“Note: some of the pictures in this preliminary datasheet are from LD-2, LD-3 is clicky switch only!”
As I understand it right your switch circuit will acts as a clicky switch. When you click it for on the circuit latches and it stays ‘on’ when you click again, it switches off. Am I right?
If so you could uses a LD-3.

5

Yes. You are right. If you push it, it stays ON, and when push it again it switches OFF.
Is it possible to disable the low voltage protection in LD3?

6

I dont think it can be disabled, you’ll have to ask led4power if it’s possible.

7

You also have to consider that double current doesnt mean double brightness for the eye
Its double brightness 4 times the lumens
Also at higher currents the LED gets less
A DTP copper board for the LED helps a lot

Typical XML2 U2 has about
355lm at 0.75A
610lm at 1.5A
986lm at 3A
with considering the incresing LED junction temperature on a standard copper board