Rene Harder wrote: > My main idea of using discrete filters though, was to keep new > components (with different packages) as small as possible to reduce SMT > assembly cost.
Yes, I was hoping that we could have one "universal" filter that's suitable for all low-frequency signals (audio, UART, etc.), given that most of the noise lives >> 100 MHz and those low-frequency signals are << 100 MHz. > Also you are more flexible with a discrete filter than with a single > component one; If we mess things up, we can just replace the caps or the > inductor and fix the problem but with a single component filter we would > need a different one and might need to change the pcb pattern as well. That's true, yes. Of course, I fervently hope that we can avoid the joy of precision-tuning those filters ;-) > However, I think we are better off using a single component filter, this > decreases complexity and risk of possible misbehavior. Great ! When we discussed integrated filters, we came up with the following components: Murata NFL18ST (0603, "T"): http://search.murata.co.jp/Ceramy/image/img/PDF/ENG/L0112S0119NFL18ST.pdf Rohm MCF182CN102 (0603, "for power supply"): http://www.rohm.com/products/databook/emi/pdf/mcf18.pdf TDK MEM2012P101R (0805, "Pi"): http://www.tdk.co.jp/tefe02/e9617_mem_p.pdf Which one would be closest to the kind of "universal" filter we're looking for ? As usual, smaller would be better :-) > I've no idea what the purpose of this resistor is/was. This seems to be > an ordinary pull-down resistor but for what I can't tell for sure. > Nothing makes completely sense to me. Are we talking about the same part ? R4401 is 220 Ohm and series, while the pull-downs in the area (R4416, R4117) are 10 k. Looks more like a current-limiter for problem conditions to me. Joerg, do you remember what it does and whether we still need it ? - Werner _______________________________________________ gta02-core mailing list [email protected] https://lists.openmoko.org/mailman/listinfo/gta02-core
