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