How to apply volume control to the class D output stage

[bbqsky]

In my design, the class D output stage is directly drived by a Sigma Delta modulator (PWM output).

My method is reducing the digital input number to the sigma delta modulator but losting dynamic range

thanks for any reply

 

[ynhe]

You can adjust the power supply to control the output power.

 

[bbqsky]

If the class D output stage want to supply more than 100mA to drive the speaker, how to realize?

 

[nickooeda]

dear bbqsky:
I am designing a class-d output stage too,can u give some advice or useful notes or the solusin of the problem meeted in designed?? thanks;

 

[bbqsky]

If you select H-bridge architecure, it is critical to ensure that the signals in each branch of the differential path have equal rise and fall times and, hence, reach the
switching threshold-voltage of the inverters at exactly the same instant.

 

[nickooeda]

there is DC offset in two branch ???

 

[eltonjohn]

ARE YOU DESIGNING THE AMPLIFIER FROM SCRATCH ??

OR USING SOMEBODY ELSE'S CIRCUIT ??
I will BE USING A MAXIM AMPLIFIER IN A DESIGN WHERE I USE IT TO DRIVE A GALAVOMETER. I HAVEN'T RECIEVED THE CIRCUIT YET ..BUT IT SEEMS THAT THE SIGNAL OUTPUT .DEPENDS ON THE SIGNAL INPUT SO IS EASY TO CONTROL WITH A PREAMPLIFIER OR CHANGING THE SCALE WITH A DAC OR EVEN CHANGING, THE VOLTAGE REFERENCE OF THE DACS

 

[bbqsky]

The signal input to the class D is PWM, it is pluse, and so is the output
I think, to control the volume, there are only 2 ways
1. PWM that input to the class D repesent different volume, the cost is lossing our system dymatic range
2. Amplitude of the output PWM (pluse) can be control.
Since the class D is composed of buffers, it want to adjust the supply voltage
If i want to have 8 levels volnme, it wil be difficult to realize and loss efficency

 

[nickooeda]

add resistor to ouput branch,of c z,it will lead to decreasing efficiency.

 

[ls000rhb]

i heard a digital volume control technology in Class D,but i dont know how it works?who have some instructions about this asepct?

 

[montage3000]

i also want this