Hi Christian, On Tue, Jul 10, 2012 at 07:04:35PM +0200, Christian Daniel -- maintech GmbH wrote:
We violate the 100mA limit by a small amount. FPGA and E4K can be switched off and the ADC doesn't consume much when no clock is applied. I don't see a problem here - at least after we fixed the power sequence to stop it from using the full 400mA directly on power up. Also a diode for external power supply is on the board. But yes - it will not be USB certified. But so far this is not a real-world problem.
Actually, now that you're doing a re-design for the SSC -> EBI change, it might be an idea to make the oscillator power supply switchable and controlled by a GPIO from the SAM3U or FPGA. At that point, there's no problem booting at < 100mA. I wouldn't expect a small low-Rds_on mosefet switch to cause any problem for the oscillator, especially since it's constant current/power... Regards, Harald -- - Harald Welte <laforge@gnumonks.org> http://laforge.gnumonks.org/ ============================================================================ "Privacy in residential applications is a desirable marketing option." (ETSI EN 300 175-7 Ch. A6)