MAX98390 DSP Enable Causes Playback Issue and Overcurrent Interrupt

Hello AliRazavi,

I am not the support person for this product but I know enough to know that we need more information. too much capacitance or inductance on the outputs can cause things like this. Please provide the schematic of what you have connected to the output and the specifications of the speaker driver. 

I will notify the correct support engineers to help you but they will need some more info. 

Thanks,

Dave T

Hi, thanks for your response.

1.The UVLO and OVC error bits in the 0x2006 register are triggered during the issue. Sometimes the UVLO bit, sometimes the OVC bit, and sometimes both are triggered together.

2.If no speaker is connected, no errors appear in the 0x2006 register, suggesting that the issue is not related to the capacitance or inductance of the speaker path. (Note: There is no EMI filter in the speaker path.)

3.I tested the setup with different speakers (1W and 5W), but the issue persisted in both cases.

4. The issue occurs even when DSP bits such as PPR_EN or DEBUZZER_EN, are enabled which are unrelated to loudness. if the DSP bits are disabled(0x23E0), the playback works fine, even at high volume.

5.I tested different sampling rates, including 8 kHz and 48 kHz, but the issue remained.

6.I used different clock sources, including MCLK (12 MHz) and BCLK (256 kHz), and the issue persisted.

this is my code:

status = HAL_I2S_Transmit_DMA(&hi2s1, (uint16_t *)i2s_tx_buffer, NUMBER_OF_SAMPLES);
HAL_GPIO_WritePin(GPIOC, GPIO_PIN_9, GPIO_PIN_RESET); //for reset
osDelay(500);
HAL_GPIO_WritePin(GPIOC, GPIO_PIN_9, GPIO_PIN_SET); //for reset
osDelay(500);
send_amp_command(0x2000, 0x01); //software reset (reset is auto-back)
send_amp_command(0x201B, 0x01); //channel A0 is enabled
send_amp_command(0x2026, 0x22); //BCLK to LRCLK ratio is 32
send_amp_command(0x2027, 0x00); //sample rate is set to 8K 0x00 0b1000
send_amp_command(0x2024, 0x40); //two bytes, I2S, others to default
send_amp_command(0x2041, 0x04); //Normal Boost Operation with 7v
send_amp_command(0x207A, 0x00);//Disable boost envelope tracker
send_amp_command(0x203F, 0x11); //Enable speaker voltage and current measurement
send_amp_command(0x23BA, 0x64);//set DSM volume to -30dB
send_amp_command(0x207D, 0x2A);//set boost converter to boost mode (no automatic, no bypass)
send_amp_command(0x2021, 0x00); //PCM channel source0

send_amp_command(0x23E0, 0b00000100); //STREO_BASE, DRC, EQ, BASS_EXT, EXCUR, PPR, DEBUZZER,THERMAL
send_amp_command(0x23E1, 0x01); //DSP global enable
send_amp_command(0x23FF, 0x01);//global enable
osDelay(500);
recv_amp_command(0x2006, &value);//important register for checking power up success

this my schematic and PCB

Hello AliRazavi,

Suspicion is that the DSM Thermal Protection algorithm is preventing sound output.

Recommend to try the following:

• Enable all DSM/DSP functions *except* THERMAL_PROT_EN (LSB of 0x23E0 should be set to 0).
• Does the sound playback work?

Quick questions for you:

• Are you using a speaker or dummy load?
• If speaker, has the speaker been characterized properly using DSM Sound Studio? Parameter Extraction is a necessary step for proper operation using the DSP features (DSM Sound Studio --> Characterize).
• Has the Characterization data for the speaker been initialized into the IC before performing the test?

From the schematic review, just two comments:

• Design overall looks very good.
• The sense line connections should be connected to SPK1+ and SPK1-. Reason: DSM Speaker Protection algorithm needs the IV sense of the MAX98390D to be able to directly sense the voice coil resistance changes with temperature.

Regards,

Michael

It has been roughly ten months and no response back so I will assume the last answer from Michael solved the problem. 

I will mark it as verified. 

Thanks!

Dave T