1-2* Lithium 2-Group 3/5-Mode 2.8A LED Flashlight Driver (LD-29)







Driver is from Fasttech.com

Official specifications:

• Product Type: Flashlight Driver
• Constant Current: No
• Driver Type: Buck driver
• Input Voltage: 3-8.4 -volt
• Output Current: 2800 mA
• PCB Height (w/o Components): 1.8 mm
• Reverse Polarity Protection: Yes
• Flashlight Modes: 2-Group 8-Mode Configurable
• Mode Count: 5
• Mode Memory:No
• Depth: 9 mm
• Diameter: 20.5 mm
• Product Weight: 3.2 g

Perfect for Cree XM-L series LEDs -- especially with T6 and U2
Dual PCB layout, 10mm total height
Designed for Cree XM-L LED emitters
Also works with four MC-E's and four SST-P7's connected in parallel
2800mA maximum current output
Low voltage warning battery protection mode triggered when voltage drops below 3V (in 1-lithium configuration) or 5.8V (in 2-lithium configuration): automatically switches to the lowest output setting, and blinks periodically
Modes:
Group 1: Lo (5%) > Mid (50%) > Hi (100%)
Group 2: Lo (5%) > Mid (50%) > Hi (100%) > Strobe > SOS

To toggle mode group:
Switch to Lo (5%) mode and count exactly 5 seconds. As soon as the flashlight blinks, half press (or quickly toggle power) to go into the other mode group.



Measurements

Tested with: Cree XM-L2
The driver uses buck mode
Driver diameter 18.6mm + 21mm
Driver height 8mm
The driver has memory, the actual mode is stored when the light is off for a short time.
A off/on will select next mode, the off has to be rather long, not to select next mode.
Mode set 1: High, medium, low, Strobe, SOS
Mode set 2: High, medium, low
The driver can be used with 1 or 2 LiIon batteries in series.
Strobe is 15Hz with 43% duty cycle
Threshold between 1 and 2 cell is between 4.5 and 5 volt



High



The drivers has very good regulation and good efficiency. It turns power down at 6.7 volt and battery warning comes on at 6 volt.



There is a maximum of 1.5 watt lost in the driver, while delivering 9 watt to the led.





No noise in the light.



The low voltage warning is a slow flashing.




With one cell the stabilization only works down to 3.7 volt, that means no stabilization for half of the runtime on a single LiIon cell.
The driver has a low voltage warning at 3 volt.









Medium



Medium has the same good stabilization and does not step down, it goes directly to low battery warning at 6 volt.




The led power is down to 2 watt.





With lower led power, the driver can sustain the medium level down to about 3.2 volt and it has very good efficiency.








Low



The regulation is also good on low, but the efficiency is slightly down.








With a single cell the driver works down to about 3 volt with full stabilization, before it goes into low voltage warning.








Strobe




Strobe is 15Hz with 43% duty cycle, the driver cannot reach full brightness with a single cell


SOS




Conclusion

The driver is a very good stabilization (Except on high with 1 cell) and good efficiency. The mode change could be better.


Notes

I have tested a slightly different LD29 driver before, with nearly the same result.

How do I test a led driver
List of all tested drivers