Does anyone know the lower limit of R8? I have a QCC5125 BT board with an ES9023P that's powered from 3.3V. It has R8=100k with give 1.6Vrms output (no load).
I would really like to get the output level down to around 1Vrms without resorting to using a voltage divider. The datasheet says for 1.9Vrms, R8=220k. If I do linear interpolation of the known values, R8 would be a negative value for 1Vrms, so I'm guessing it won't work. That's assuming the change is linear though.
I would really like to get the output level down to around 1Vrms without resorting to using a voltage divider. The datasheet says for 1.9Vrms, R8=220k. If I do linear interpolation of the known values, R8 would be a negative value for 1Vrms, so I'm guessing it won't work. That's assuming the change is linear though.
Ok, I managed to find a small 100k trimmer in my stash and used it to carefully replace the 0603 100k resistor.
Hooked up my scope and found that the output would completely collapse below 1.15Vrms with no load. With a 10k load it would collapse below 1.32Vrms. After setting the trimmer to get 1.35Vrms, I removed it and it measured 30k.
The BT module is going in a TDK boombox that I've had for a decade. I lose a lot of range on the volume control with too high of input signal. I'll just have to live with however much range I get with 1.35Vrms.
Hooked up my scope and found that the output would completely collapse below 1.15Vrms with no load. With a 10k load it would collapse below 1.32Vrms. After setting the trimmer to get 1.35Vrms, I removed it and it measured 30k.
The BT module is going in a TDK boombox that I've had for a decade. I lose a lot of range on the volume control with too high of input signal. I'll just have to live with however much range I get with 1.35Vrms.