Review/Test of 17mm 2-Mode LED Driver Circuit Board for Flashlight DIY

DSC_4041 DSC_4042

DSC_4043 DSC_4044


Driver is from Fasttech.com

Official specifications:


Measurements

Tested with: Cree XM-L2
Diameter: 17mm
Height: 3mm
Modes: Low, High
Driver changes mode with each turn on.
Low is with pwm at 207Hz and 17% duty cycle.
Driver is direct drive.
DC resistance in driver is about 0.18 ohm at 2A (Measured directly at the driver pcb).



High

17mm%202-Mode%20LED%20Driver%20(GK-003A6)%20HL

This driver is only a direct drive driver, i.e. it is only a switch with a bit of resistance in. This means that the input and led current is the same (The curves are on top of each other) and the voltage/current curve will be very close to the led voltage/current curve.
I did not test higher than 3.9 volt, because the led is specified for 3A and I passed that at 3.9 volt (Most LiIon batteries will be below 3.9 volt when loaded with 3A. See my comparator for actual data).
I cannot see any traces of a low voltage protection, but the led by itself will to a large degree protect the battery.

17mm%202-Mode%20LED%20Driver%20(GK-003A6)%20HLDriver
17mm%202-Mode%20LED%20Driver%20(GK-003A6)%20HLLed

17mm%202-Mode%20LED%20Driver%20(GK-003A6)%20LH

Starting from a low voltage, shows that the driver starts at around 2.9 volt.

17mm%202-Mode%20LED%20Driver%20(GK-003A6)%20LHDriver
17mm%202-Mode%20LED%20Driver%20(GK-003A6)%20LHLed


High%203.6V

Being direct drive, the driver does not add any noise to the current.



Low

The power and efficiency calculations does not work here, the efficiency will be very close to the high efficiency

17mm%202-Mode%20LED%20Driver%20(GK-003A6)%20HL%20low

The average current goes down when the led is switches on/off at a fast rate.

17mm%202-Mode%20LED%20Driver%20(GK-003A6)%20HL%20lowDriver
17mm%202-Mode%20LED%20Driver%20(GK-003A6)%20HL%20lowLed

Low%203.6V

The actual pwm frequency is about 207 Hz (The dip in the pulses is due to my power supply, not the driver).



Conclusion

This is a simple driver with limited applications, i.e. only LiIon batteries and led must be suitable for direct drive.
I wonder why the driver has two IC's, it is probably a microprocessor and a EEPROM (For remembering mode), but why use an external EEPROM when most microprocessors has one build in.



Notes

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