John Syne writes: > > a power supply that is spec’d at 4A should not shutdown when it sees a > 4A load, but rather, it should current limit at 4A. If the power supply is > spec’d at 4A, then 4A should not be treated as a short circuit. >
That's impossible. You can't recommend that fundamental electrical laws be overridden. :P If a PSU current limits at 4A, it can do so only by reducing its output voltage. This may then drop below specification for its load and this can have very bad consequences such as non-stop rebooting. There is no way for the voltage to be maintained above its minimum spec while still providing a current limit. This is the reason why ensuring that startup inrush transients cause no harm must always be handled within the design of the load, ie. the BBB in this case. The load is a black box as far as the external PSU is concerned, so the external PSU has no means to perform this protective function while still maintaining regulation. (Blowing a fuse does not maintain regulation, but is sometimes the only practical alternative.) In other words, a load can demand a *minimum* current capability under a rated voltage specification, but it cannot demand a *maximum* current capability unless it can cope with arbitrary drops in supply voltage. Such voltage tolerance is generally not available in electronic circuitry today, certainly not in BBB. -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to beagleboard+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/beagleboard/CAM0uzStPOH3i%2B0pH2O4Bz3E_kcggLrJu9yZSaOO4HzZ%2BkLQ3mg%40mail.gmail.com. For more options, visit https://groups.google.com/d/optout.
