I am trying to recreate at nanjg 105c driver for a prototype I am working on. I do not need the round double sided board. It will all be affixed to a 1"x1" board. I've located a fairly poor pinout diagram but i am having trouble determining what resistors and diode are used. Does anyone know? Also, i am going to be driving an XM-L at its max and wondering if it would be ok to push it beyond that because it with only ever strobe, never constant on. If so, how much extra could I run to it? Also is there a better way or cheaper and less work way to drive the XML at its max? I will endup coding the tiny myself.
Recreating a 105C driver
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DIWdiver
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Hi, and welcome to the forum!
As I recall from the days when the XM-L was actually a modern LED, it could be driven to 5A or more if kept from overheating. IIRC, beyond that you didn't get any additional light (and then it starts dropping). What kind of duty cycle will you have on the strobe? What kind of heatsinking on the LED? If the duty cycle is low enough and the pulse short enough, I might even push to 6-7A.
The '7135 driver chips are dead simple to use, and nearly foolproof. A sufficient number of them and a micro to turn them on and off, should be about all you need. They are pretty cheap, so unless you are building many boards, I wouldn't bother trying to find a cheaper way. If you are worried about heatsinking, there are ways that are easier to get good heatsinking. Less work? Probably not.
A bypass capacitor on the micro's power pins would be a good idea. 0.1uF is a pretty common value for this purpose, but I'm not sure what the 105C actually uses.
A diode would be for reverse-polarity protection. It looks like on the 105C board it only protects the micro, so almost any diode would be fine. It's not really necessary unless you are worried about hooking the supply backwards. That WILL destroy an unprotected micro, apparently it does not damage the '7135s.
The resistors are to divide the input voltage down to a point that the micro can read it, so to provide low battery detection. I'm not familiar enough with that micro to know what the max voltage on the analog inputs is. On one picture of the board I saw, I could read the values as 4.70K and 19.1K. It looks like the 4.7K is connected to ground, the 19.1K to Vin.
As I recall from the days when the XM-L was actually a modern LED, it could be driven to 5A or more if kept from overheating. IIRC, beyond that you didn't get any additional light (and then it starts dropping). What kind of duty cycle will you have on the strobe? What kind of heatsinking on the LED? If the duty cycle is low enough and the pulse short enough, I might even push to 6-7A.
The '7135 driver chips are dead simple to use, and nearly foolproof. A sufficient number of them and a micro to turn them on and off, should be about all you need. They are pretty cheap, so unless you are building many boards, I wouldn't bother trying to find a cheaper way. If you are worried about heatsinking, there are ways that are easier to get good heatsinking. Less work? Probably not.
A bypass capacitor on the micro's power pins would be a good idea. 0.1uF is a pretty common value for this purpose, but I'm not sure what the 105C actually uses.
A diode would be for reverse-polarity protection. It looks like on the 105C board it only protects the micro, so almost any diode would be fine. It's not really necessary unless you are worried about hooking the supply backwards. That WILL destroy an unprotected micro, apparently it does not damage the '7135s.
The resistors are to divide the input voltage down to a point that the micro can read it, so to provide low battery detection. I'm not familiar enough with that micro to know what the max voltage on the analog inputs is. On one picture of the board I saw, I could read the values as 4.70K and 19.1K. It looks like the 4.7K is connected to ground, the 19.1K to Vin.
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