Laser driver board, a fast current source switchable with a TTL input. Place this as close as possible to the Laser with short wires.
Choose R1, R5 and R7 to achieve desired target current for given laser
(I ≈ (Vref - 0.6) / (R5+R7); Vref=0V..5.6V).
Adjust desired current by reference voltage with trimmer before connecting
laser. Measure current through laser via (+12V - TP4) / R1.
Depending on the inductivity of the supply line or desired current, not all of the 10μ caps (C2..C8) might be needed.
| Qty | Reference(s) | Value | Footprint |
|---|---|---|---|
| 2 | C1, C11 | 100n | 0603 |
| 7 | C2, C3, C4, C5, C6, C7, C8 | 10u | 1210 |
| 1 | C9 | 100n | 0805 |
| 1 | C10 | 100p | 0603 |
| 1 | D1 | 5V6 zener | SOD-323 |
| 1 | J1 | CONN_01X03 | JST_EH_B3B-EH-A_1x03_P2.50mm |
| 1 | P1 | LaserOut | JST_EH_B2B-EH-A_1x02_P2.50mm |
| 1 | Q1 | BCP5616Q | SOT-223-3 |
| 1 | Q2 | DMN2058UW | SOT-323_SC-70 |
| 3 | R1, R5, R7 | 6R2 | 2512 |
| 1 | R2 | 2k2 | 0603 |
| 1 | R3 | 470 | 0603 |
| 1 | R6 | 680 | 0603 |
| 1 | R8 | 1k | 0603 |
| 1 | RV1 | 10k | Multi-turn trimmer (through-hole, 2.54mm pitch) |
| 1 | U2 | MIC920 | SOT-353_SC-70-5 |
There are probably better ways to have a fast current switching driver for lasers that don't have a feedback line. Suggestions welcome.