Hi Attila, Attila Kinali wrote: > Hi, > > I finally got around to measure the internal supply pins of my > net5501 to see what exactly is going on. What i see are very very > short (<1us) drops of the 12 down that are larger than 1V. I guess > the drops of the 3.3V and 5V supply that i see at the same time > come from the 12V drop. But with the measurement equipment i have > here and the lack of schmeatics, i cannot be sure. (it could be the > other way as well)
The net5501 power input is decoupled with a low esr 330uF electrolytic capacitor and two 2.2uF ceramic capacitors. The 5V, 3.3V and CPU core regulators each have 1000 uF low esr electrolytic capacitors and plenty of large ceramic capacitors. So pulses like that are simply not possible, you might want to ensure you measure correctly, you can easily pick up noise from the inductors or other sources. Maybe with a 50 ohm probe directly over a capacitor. > The inductors look like they can take 1-2A each.. The inductors are of course dimensioned to the need of the system, the 5V rail and 3.3V rail are both designed for 3.5A each, there should be at least 12W combined left for expansion.... > Hence i'd like to try another power supply but i don't have any > 12V with>3A here, only a 16V. Unfortunately, there is no specification > on what the net5501 can take as 12V suplly and whether these 12V > are connected to the harddisk or PCI connectors. > > Hence i would like to ask the following questions: > * What is the exact specification of the 12 supply input? As somebody already said, the official spec is 6-20V, absolute max is limited by the 26V TVS. > * Where are those 12V connected to? The 12V circuit is special designed to enable use of a 3.5" HD.... If you supply 11-13V to the unit then a mosfet switch direct the power input directly to the 12V rail, you can then draw max 2A. Otherwise a dc-dc converter make 12V from 5V, with that you can draw max 0.5VA. The same converter make -12V for the PCI slot, at about 0.3A. The +12V rail goes to the HD power connector and the PCI slot. The principle is that you can then use a 3.5" HD if you supply 12V to the unit. Normal 2.5" drives don't use 12V. > * Is there any stabilization or voltage limiter between the supply input > and the harddisk and/or PCI connector? See above. And yes, this info should be in the manual. I do have a draft here that will be finished and released soon.... Best Regards, Soren Kristensen CEO & Chief Engineer Soekris Engineering, Inc. _______________________________________________ Soekris-tech mailing list [email protected] http://lists.soekris.com/mailman/listinfo/soekris-tech
