IVX
Major Contributor
Hi everyone, I keep playing with my proto DAC+HPA project and found abnormally high THD(.002%@1kHz 0..-20db pretty much the same) with SPDIF input and default reg#0 = 0x00 i.e. clk_gear = XI/1. If clk_gear = XI/2 or XI/4 either XI/8 the THD becomes better, and XI/8 THD have the lowest value .0004%(without TH_COM cheating or .00025 with). The problem is ES9038Q2M does work with SPDIF Fs=192kHz(96kHz ok with XI/2 and XI/4, 44-48 ok with XI/8) only if reg0=0, hence I've no chance to get decent THD at 192 at all. I quite happy with 44-48 SPDIF input because it does work with XI/8 setting, THD at 96 .0007% is so-so, and only if MCU will dynamically setup reg#0 according to current audio format(if 192 then reg#0 = 0x00, 96 then reg#0 = 0x08, 44-48 reg#0 = 0x0C). Such on the fly update makes muting for 1/2 S, it is really bad if a track-list contains different formats. The clock is SiT8209 100MHz, I've tried 50MHz Xtal with ES9038Q2M internal oscillator and got a bit better THD but SPDIF 192 didn't work at all, hence 100MHz isn't max XI frequency but rather minimal one or ONLY the frequency allowed. I use CM6642 as USB/SPDIF bridge(5x6mm QFN with 3-5pcs 0402 surrounding that allows me to fit all in the USB dongle like case), and I have the same THD for 44.1 either 192 in another my design where WM8804 does convert SPDIF into I2S, hence, the root cause is ES9038Q2M.
Any input, ideas welcome.
Any input, ideas welcome.