I have one of these: http://sdr-kits.net/PA0KLT_Description.html
built with the CML output Si570 that goes to 1417 MHz (!) There is a schematic in the assembly manual that's linked to from that page. They use 100n and 1n capacitors in parallel on Vdd and 4K7 pullups on SCL/SDA. They have 100n DC blocks directly on the output pins. Into a 50 ohm load, the CML outputs produce about 4dBm as I recall. Obviously, the CMOS output will be different. There is a review of a different Si570 kit on the Clifton Labs site: http://www.cliftonlaboratories.com/si570_kit_from_k5bcq.htm I got similar results comparing my kit against an HP 8640B. The Si570 beats the 8640B close in just as shown on the Clifton Labs site. Some Softrock SDR radios also use the Si570. They use a single 10n capacitor on Vdd and 2K2 pullups...: http://www.wb5rvz.org/ensemble_rxtx/03_lo I have the Softrock Ensemble RXTX. It works fine on RX, but unfortunately I have not been able to get satisfactory image rejection on TX. I suspect the FST3253. So, it looks like decoupling isn't that critical - 10n or 100n||1n in these examples. 1K pullups on SDA/SCL seem to be overkill and anything reasonable <= 4K7 should work. Orin. On Tue, Nov 18, 2014 at 7:59 AM, Jim Lux <jim...@earthlink.net> wrote: > I'm sure someone here has fooled with the Si570. > I just got a few of them (CMOS output), and am about to deadbug one of > them to fool with it (unless there's some convenient protoboard out there > available.. I didn't look too long and hard, but some casual googling > didn't find one). > Looking at AN334 from SiLabs: > It looks like you just need a 10nF bypass on the Vcc, a pull down on the > OE (1k), 1k pullups to 3.3V on SDA/SCL (which is going to be driven by a > 3.3V teensy 3.0/3.1 microcontroller) > 150 ohm loads to ground, followed by a 0.1 uF DC block? > > I'm going to be running it at less than 50 MHz (although the parts I got > are preset to 100 MHz) > > Any traps for the unwary? > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/ > mailman/listinfo/time-nuts > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.