BLF driver GT-buck [rev 04][tried and tested]
author: DEL
2 layer board of 1.82 x 1.82 inches (46.2 x 46.2 mm)
Uploaded:
September 26th 2017
Shared:
December 8th 2017
Total Price:
$16.50
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
| Part no. | Value | Type | Package |
|---|---|---|---|
| C1 | 1u | X7R, 25 V | C0603 |
| C2 | 3.3u - 10u | X5R, 16 V | C0805 |
| C4 | 1u | X7R, 25 V | C0603 |
| C11 | 4u7 | X7R, 50 V | C1206 |
| C12 | 4u7 | X7R, 50 V | C1206 |
| C13 | 4u7 | X7R, 50 V | C1206 |
| C14 | 4u7 | X7R, 50 V | C1206 |
| C15 | 470p | C0G, 50 V | C0603 |
| C16 | 1u | X7R, 25 V | C0603 |
| C17 | 4u7 | X7R, 50 V | C1206 |
| D1 | SS34 | Schottky, 40 V, 3 A | SMC/DO-214AB |
| L1 | 10u | Bourns SRR1208-100ML | 12x12x8 mm |
| Q1 | AOD417 | P-chan <50 mohm <20 nC | TO252 / DPAK |
| R1 | 1M | 1% | R0603 |
| R2 | 47k | 1% | R0603 |
| R3 | 10R | 1% | R0603 |
| R4 | 10k | 1% | R0603 |
| R5 | 3k3 | 1% | R0603 |
| R6 | n/p | ||
| R7 | 1k | 1% | R0603 |
| R8 | 33k | 1% | R0603 |
| R11 | 0R091 | 1%, <300 ppm/C, 1-3 W | R2512 |
| R12 | 47k | 1% | R0603 |
| R13 | n/p | ||
| R14 | 4k7 | 1% | R0603 |
| U1 | ATTINY85-20SU | SOIC-8 | |
| U2 | MIC5235-5 | 5 V LDO regulator | SOT23-5 |
| U3 | LM3409 | Buck controller | HVSSOP-10 |
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)
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
| Part no. | Value | Type | Package |
|---|---|---|---|
| C1 | 1u | X7R, 25 V | C0603 |
| C2 | 3.3u - 10u | X5R, 16 V | C0805 |
| C4 | 1u | X7R, 25 V | C0603 |
| C11 | 4u7 | X7R, 50 V | C1206 |
| C12 | 4u7 | X7R, 50 V | C1206 |
| C13 | 4u7 | X7R, 50 V | C1206 |
| C14 | 4u7 | X7R, 50 V | C1206 |
| C15 | 470p | C0G, 50 V | C0603 |
| C16 | 1u | X7R, 25 V | C0603 |
| C17 | 4u7 | X7R, 50 V | C1206 |
| D1 | SS34 | Schottky, 40 V, 3 A | SMC/DO-214AB |
| L1 | 10u | Bourns SRR1208-100ML | 12x12x8 mm |
| Q1 | AOD417 | P-chan <50 mohm <20 nC | TO252 / DPAK |
| R1 | 1M | 1% | R0603 |
| R2 | 47k | 1% | R0603 |
| R3 | 10R | 1% | R0603 |
| R4 | 10k | 1% | R0603 |
| R5 | 3k3 | 1% | R0603 |
| R6 | n/p | ||
| R7 | 1k | 1% | R0603 |
| R8 | 33k | 1% | R0603 |
| R11 | 0R091 | 1%, <300 ppm/C, 1-3 W | R2512 |
| R12 | 47k | 1% | R0603 |
| R13 | n/p | ||
| R14 | 4k7 | 1% | R0603 |
| U1 | ATTINY85-20SU | SOIC-8 | |
| U2 | MIC5235-5 | 5 V LDO regulator | SOT23-5 |
| U3 | LM3409 | Buck controller | HVSSOP-10 |
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)
