HDMI v2.1 Specifications including HDMI v2.1a, HDMI v2.0 HDMI v1.4 and older.HDMI Best Practices Installation Guidelines and Recommendations.HDCP Error / HDMI Handshake (Picture Sync) Troubleshooting and Guidelines.Ethernet Networking Cable : CAT5 vs Cat6 vs Cat7 vs Cat8 : What is the Difference ? Wiring and Specifications.DSTV XtraView Installation & Frequencies (DSTV User Bands) for Multichoice Explora/HDPVR and other decoders.Home Entertainment Wiring Diagram – HDMI to AV, HDMI Splitter, HDMI Extender, HDMI to VGA, VGA to HDMI.HDMI Specifications and Technical Info | HDMI Voltages, HDMI Wire Layout, HDMI Channels DDC, TMDS and CEC.2.4Ghz vs 5Ghz Wifi Bands & Wifi 4 vs Wifi 5 vs Wifi 6 Technologies.Technical Info | Wiring Diagrams Menu Toggle.so be careful on the phase jitter caused by the cap.100nF is about 75 ohms at 20kHz thus there will be excessive phase jitter when terminated by 75R but not so when going into high impedance CMOS input. But if all Rx’s also have a series cap, after the 75R terminator, it won’t matter.since single supply CMOS uses some input threshold between Vss and Vdd, it must be self biased on the Rx so the cap may be on the Tx output and **not before* the 390R resistor.The effects are quite different as the CMOS IC is high impedance and self biased to Vdd/2 or self biased with negative feedback. Some Rx’s may have the same 75R termination to 0V then a series 100nF to CMOS IC. All schematic I have seen show the transmitter, Tx has 75 R then a series 100nF cap. ** Although I’ve never used S/PDIF what seems to be wrong and easily overlooked is the Average DCbias level. The RdsOn value in FETs rises as Vgs=Vdd reduces. Zo= (Voh-Vdd)/Ioh = (4.3-4.5)/-4mA=50 may have a wide tolerance but it is a good value to remember. levels or even the max current when used for non-std. Since it is presence of a transition is important, not the polarity, for BiPhase Mark.ĭon’t be fooled by driver specs at Vol, Voh intended to be logic load std. Isn’t that a lot more than the 200mV min you need ? The CMOS 74HC04 is a 50 Ohm driver typ so two become 25 Ohms and which puts the result very close to 74.6 Ohms 900mV. Note if the receiving DAC sucks at rejecting jitter, it will sound better with a higher value for C6, like 1♟. If you're a perfectionist, add a ferrite bead in the supply line. The buffer should have adequate decoupling. Simply power your buffer chip from 3V3 instead of 5V (ie, cut the 5V trace and solder a wire to 3V3 instead) and change resistor values. You can probably use your existing board. Insert the buffer between the output of WM8804 and R8 in the above schematic. I wouldn't use 74HC powered from 3V3 as it will be a bit slow. Its input will be compatible with WM8804 output levels. If you want to use a buffer, then it makes sense to use a chip powered from 3V3. This is not likely to matter in practice. If you want an exact 75R source impedance you'll need to adjust resistor values taking into account the exact output impedance of the chip. This will work just fine with any chip that outputs 3V3 LVCMOS SPDIF. Resistor values create a 75R source impedance and the correct voltage levels. WM8804 has a SPDIF output, and it is designed to drive a coax if you use the resistors specified in the application schematic which is provided. Solution #1 is straight from WM9904 datasheet: and this 3V3 chip will be compatible with your WM8804 output. You can do it with a 3V3 chip just as well. To output +/- 0.5V levels, you don't need a chip powered from 5V. Then we have a resistor divider which brings the output level down to +/- 0.5V. Its inputs are not really compatible with LVCMOS 3.3V, which is why it does not work. Then, you use TC7W04, a 74HC-equivalent chip powered from 5V. WM8804's SPDIF output uses LVCMOS 3.3V levels. The other answers missed the obvious, so here we go.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |