Bocian's Programmable 13A driver
Driver is made as a hobby project by a guy called Bocian, he sells it at CandlePowerForums and BudgetLightForum
Official specifications (There is none, only a instruction sheet):
- Can be ordered in 2.8 or 3.04A versions.
- 4 modes selected from 11 brightness settings.
- Strobe with same brightness as selected brightness.
- Battery measurement.
- Low battery warning.
- Very high pwm frequency.
Tested with Cree XM-L2 led
Driver diameter 16.9mm
Driver height 6.3mm
Driver uses linear regulation with pwm.
Driver has 4 programmable brightness levels and a strobe mode.
The default programming is 0,15%, 10%, 32%, 100%. This can be restored with a 8 off/on cycles.
The driver has memory and a short off/on will select next mode.
Pwm is 18kHz
Strobe 4Hz with 50% duty cycle, brightness follows selected mode.
This driver is based on a standard 7135 driver with a slight hardware modification and a much more advanced program.
The different functions/possibilities can be accessed with a number of clicks:
1 click: next brightness level.
2 click: previous brightness level.
3 click: strobe.
4 click: report battery level.
6 click: program brightness for selected level.
8 click: reset to default.
All the oscilloscope traces are done at 3.6 volt.
As usual pulsing current (i.e. pwm) makes it difficult to calculate power and efficiency. In any modes except high I am calculating with a fixed led voltage, but due to the high pwm frequency it is not very precise.
Due to the high pwm frequency the power and efficiency calculations has large errors in the lower modes
Brightness level 100%
In high (100%) mode the driver is just a 8x7135 driver, except it starts stepping down and giving warnings when the battery voltage is low and it will turn off when the battery is empty.
No pwm in high, it is completely disabled.
Brightness level 70%
Due to the high pwm frequency, the pwm pulse is not square, but has a more smooth shape.
Brightness level 50%
Brightness level 32%
Brightness level 25%
Notice that the brightness is only stable above 4 volt now, this is due to the fast pwm.
At 25% less than half of the on time has stable brightness, i.e. the line is horizontal, the rest of the time is used to turn the 7135 chip on.
Brightness level 18%
Brightness level 10%
At 10% the driver does not even reach stable brightness.
Brightness level 4%
Brightness level 1%
Brightness level 0.15%
This mode is at the limit of my setup, the steps in the input current is my resolution in the power supply.
The driver does barly turn on in this mode.
Brightness level 0.02%
Sorry, no curves. The level is to low to register in my setup.
The specifications also has this note: not always visible – depends on variability of electronic components parameters
The strobe can be activated at any brightness level and will use the same pwm setting, in addition to strobeing.
At 100% there is no pwm.
The strobe frequency is 4 hz.
The driver has a build in battery check, that will show a number of flashes, depending on battery voltage.
It is interesting to see what can be done with this driver. The programmable modes makes it much more flexible.
Except for the high pwm (I would have preferred 1 to 2 kHz), I like the driver.
The driver was supplied by Bocian for review.
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