MUSIC DAC/ADC PCB

Rick Raffanti

Nov 23, 2010

Circuit changes

• Add ADR441 reference, U108

• Add loopback filters

• Change U103 from LM1117-5 to LP3856-5 (lower dropout v, bigger pkg)

ADC chips- 2.6W each

Heatsink- thermal tape mount(couldn’t find screw-attach type)

Thermal plane model

Thermal model- 1 oz plane

Thermal model- Spice

Placed power sources roughly where they are on existing designs, on 20cm by 12cm grid

Used 5 ea 0.5C/W mounting screws each edge

Used 23.7C/W junction-ambient for ADC chips

ADC chip junction temp rise

• Single 1 oz plane: L 49C, R 54C (above ambient)• Single 3 oz plane: L 36C, R 42C• Add 4 1C/W mounting points near each ADC chip (8 in all):

– L 27C, R 28C

• Moved 1.8W regulator near RH edge- L 27C, R 28C• Single 6 oz plane (=? 2 3oz planes): L 18C, R 19C