Other Parts Discussed in Thread: TPS61089
I have a TPS61089EVM connected to an existing board to boost a LiPo battery to a higher voltage for driving speakers. The six 8Ω speakers used in the design are driven by half bridges controlled using PWM signals. For testing I'm using a bench power supply rather than a LiPo battery. The output of the TPS61089 is connected to the VHAP supply net shown in the schematic snippet below:
If I drive all six speakers with the same wavetable, I encounter occasional dips in the output of the TPS61089EVM output. The R1-R3 resistors have been reworked for 6.1V output, but otherwise remain unchanged (current limit, switch frequency, etc). Oscilloscope captures are below, with yellow representing the TPS61089 output and fuschia representing the bench supply input:
Waveform playback without Vout 'dips':
Waveform playback with Vout 'dips':
I measured the input supply current peaks at around 1.1A, well below the TPS61089EVM's default 8.1A current limit and the bench supply's 3A current limit, and don't observe sizable dips in the input supply voltage. What is the cause of these dips, and what can I do to prevent them?
