Other Parts Discussed in Thread: PCM5102A
Hello
I found that there are 4 RC values in datasheet and EVM
in datasheet 8.7.1. Many applications require an external low-pass RC filter (470Ω + 1.2nF) to provide sufficient out-of-band noise rejection.
470R+1.2nF
in datasheet 8.7.1. The PCM5242 can also support single ended outputs, using OUTLP and OUTRP respectively. A single 470Ω and 2.2nF capacitor can be used on each pin in single ended mode.
470R+2.2nF
in datasheet 8.7.1. Figure 66. Optional Low Pass Filters
470R+4.3nF
in EVM 6.1 Schematic
499R+1nF
There are some question confusing me..
1. Are those values respresenting the filter values of following?
470R+1.2nF ~ 282k
470R+2.2nF ~ 154k
470R+4.3nF ~ 78k
499R+1nF ~ 318k
If so, how to determine the optimal value? why does single end need 154k, but differential can choose between 78k-318k?
2. What is the range of R should be use?
the datasheet and EVM are using 470-499R,how to determine this value as well?
I just tried 1k in PCM5102A(not sure if it's same as PCM5242), the sound was horrible compare to 500R.
Thank you very much.