ledboard_4x4_hd

LEDBoard_4x4_HD

PCB originally designed for magic_amulet,
but now used in magic_crystal

Overall Size:
33mm x 14mm

PCB

4layer board - uses 150mil traces and 100mil trace spacing
shown pcb came from aisler

parts

LED-Driver: TLC5957 (48ch CC 9-16Bit-PWM driver)
more information in AppNote Build a High-Density, High-Refresh Rate, Multiplexing Panel With the TLC5957

LED: Rohm MSL0402RGBU (1.8x1.6x0.5mm RGB)

BOM

can be ordered with aisler parts-package
or also with this list at mouser
or with plain part numbers:

Qty.    Mfr. No             Manufacturer            Description
16      MSL0402RGBU1        ROHM Semiconductor      Standard LEDs - SMD RGB 624/527/470nm 5V 400/550/180mcd 30mA
1       TLC5957RTQR         Texas Instruments       LED Lighting Drivers 48-channel, 16bit ES PWM LED driver
2       GRM188R61A226ME15D  Murata                  Multilayer Ceramic Capacitors MLCC - SMD/SMT 0603 22uF 10volts *Derate Voltage/Temp
2       GCM188R91E104KA37D  Murata                  Multilayer Ceramic Capacitors MLCC - SMD/SMT 0603 0.1uF 25volts X8R 10%
1       ERJ-PB3B7501V       Panasonic               Thick Film Resistors - SMD 0603 Anti-Surge Res. 0.1%, 7.5Kohm

power & cooling

if you want to drive the leds with full power (up to 25mA/color) you definitely need a heatsink.
the pcb backside get to >= 60°C very fast without a heatsink!

also remember that one board needs up to 1.2A@5V = 6W

constant current

RIREF(kΩ) = VIREF(V) / IOLCMax(mA)× Gain  | / Gain
RIREF(kΩ) / Gain = VIREF(V) / IOLCMax(mA)  | swap
Gain / RIREF(kΩ) = IOLCMax(mA) / VIREF(V)  | x VIREF(V)
Gain / RIREF(kΩ) x VIREF(V) = IOLCMax(mA)

Gain / 7.4kΩ x 1.2V = IOLCMax(mA)

Gain	BC	IOLCMax
20.0	0x0	3.2mA
39.5	0x1	6.4mA
58.6	0x2	9.5mA
80.9	0x3	13.1mA
100.0	0x4	16.2mA
113.3	0x5	18.4mA
141.6	0x6	23.0mA
154.5	0x7	25.0mA

Software

• arduino library
• CircuitPython library