In an early project phase you often get asked the question to use either centralized or distributed power management for the electrical system. Is there a general rule for which one that gives the best material cost and best performance?
The last time I was asked this question the system included 5 circuit boards and five main voltage supplies (analog +12V, analog -12V, digital 12V, digital 5V and digital 3.3V.) Most supplies would be using around 50W at peak power and would have to be made with switch regulators. The boards had about 0.5 meters distance between each other and every board was using all supply voltages. A distributed power management would require up to 25 small switch regulators but only a single pair of power wires to connect each board. A centralized power solution would only require 5 large switch regulators but several meters of extra cables.
My assumptions were:
1) Distributed power management has higher chip cost but lower cost for cabling.
2) Distributed power is more reliable because additional cabling has a higher failure rate than additional IC.
3) Distributed power has better EMC/EMI performance.
4) Power efficiency would be about the same for centralized and distributed power.
Any objections or other things that should be taken into consideration?
In the end we choose to use centralized power to save development time for the hardware team. I did require extra development time for the mechanics team tough, so it likely that we did not gain any time.