This is the driver used in the production version of the BLF GT light.

[Bunny logo is the property of Lumintop, manufacturer of the GT]

Features

• 2.5 A buck regulator with constant current output
• Attiny85 MCU, supported by NarsilM 1.2 and up firmware
• Most BLF ‘1-channel’ and ‘2-channel’ firmware can be made to work with a few simple changes
• 0.4 V dropout voltage, <150 μA parasitic drain
• Support for button indicator light

Revision changes

• 00 - driver prototype
• 01 - cosmetic changes
• 02 - adapted to the prototype 1 hosts and cell cradles (dedicated ground ring)
• 03 - copper added back to retaining ring area
• 04 - adapted to the production version hosts and cell cradles (retaining ring for ground)

Suggested parts list

Output current range is determined by the R4/R5 ratio and the sense resistor (R11) value. R4/R5 could be used to lower the current, but to increase the current R11 should be adjusted:

• Iout = 0.248 / R11 - 0.15
• or R11 = 0.248 / (Iout + 0.15)

(the 0.15 offset is determined by the inductor ripple current and will change if the inductor value or switching frequency is modified)

Daughter board for the DDm-K2 driver board.

https://oshpark.com/shared_projects/F9jb3vFP

The switch is a NO SMD 6.2x6.2x3.1 mm tactile type. The LEDs have 0805 footprints. Normally R1 is not populated. A jumper or small-value resistor here wires the two LEDs to be driven in parallel.

5+1 7135 driver for Solarstorm/Fandyfire K2 lights.

Revision changes

• New

Needs the DDm-K2-SW daughter board for the tactile switch and indicator LEDs:

https://oshpark.com/shared_projects/0o6V4Iia

‘Standard’ BLF parts list, except for:

• R1 and R2 are populated if MCU pin 7 is used for cell voltage monitoring. This could, however, be done using the software-only method of Vcc vs. the internal 1.1 V reference.
• R7 is populated when re-purposing pin 7 to drive a second indicator LED, as per the stock driver.
• There is an R1 on the back of the switch board. A jumper here rewires the two indicator LEDs in parallel, both to be driven from MCU pin 3.
• C3 = 10 uF is optional
• C4 = 100 nF is optional

LDO version of the Yezl Y3 driver, for 2S lights.

• Suggested LDO: MIC5235-5.0, SOT23-5
• C1, C2, C3: 4.7 uF (but 2.2 - 10 uF is OK), X5R/X7R
• R5: 10 ohm