Hi
We saw small noise when pull reset pin from high to low at BTL mode. Any suggestion how to solve it?
Waveform capture as below (reset pin high to low) , Ch1 and Ch2 are output waveform. CH1 - Ch2 shown as the red waveform , see there is a pulse.
Below waveform shown reset pin from low to high, the waveform looks ok
Our schematics as below
Hi Sam,
We done the test as suggest above . Would you check if there is any solution ? thanks!
1. Use DC coupling probe. (waveform captured as below)
The original image was measured by two DC-coupled probes, and we took the difference between them to show the pop noise waveform.
We add one image, which is measured by the differential probe. It can measure the BTL output of OUTA and OUTB directly.
We can find two pulses after the RST pin changes to low. We check the PWM waves of OUTA and OUTB, and it looks like the asymmetric waveform caused the pulse.
These test results are obtained using a 4ohm speaker.
2. Connect a speaker on the output, and see if there is pop noise during the reset. If 2V pulse exists, there should be a loud pop noise. (Waveform as below)
We’ve used 4ohm load(without inductance), the pop noise looks smaller than 4ohm speakers. But it still is a issue for us when we used a 4ohm speaker.
