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PUREPATHSTUDIO: Inquiry about completely disabling protection features (Smart Amp & BOP) on TAS2781 for max power testing

Jaesung Kim
Prodigy 30 points

Part Number: PUREPATHSTUDIO
Other Parts Discussed in Thread: TAS2781

To Texas Instruments Audio Team,

I am a hardware engineer developing a product using the TAS2781. I am currently conducting a stress test where I need to force a continuous 4V sine wave output to the speaker.

I understand from the "Smart Amp Tuning Guide" that I must use ROM Mode to truly bypass the Smart Amp protection algorithms. And I have the following questions to clarify how to achieve a "protection-free" state:

1. When I switch the device to ROM Mode via PPC3 (Device Control panel), are the Excursion and Thermal Protection algorithms automatically disabled? Or do I need to manually write to specific registers to disable them even in ROM Mode?

2. I am using a DC power supply for this test, not a battery. In this case, Brown Out Protection (BOP) could affect the result? if then, Could you please provide the specific Register Address and Bit settings to completely disable the BOP feature?

3. Other Hardware Limiters Besides Smart Amp protection and BOP, are there any other internal limiters (e.g., Peak Voltage Limiter, Hard Limiter) enabled by default in ROM Mode? If so, how can I disable them?

4. Recommended Sequence My goal is to bypass ALL protections and force the amplifier to output the input signal as-is (pure 4V output) on my custom board. Could you recommend the correct register configuration sequence to achieve this?

  • 0
    Prodigy 30 points

    To add to question 4, I would like to know not only about custom boards but also about EVM.

  • +1 in reply to Jaesung Kim
    TI__Mastermind 22035 points

    1. DSP processing is fully bypassed it is like a simple amp. all speaker protection is bypass

    2. Book 0 Page 0 Register 0x1F bit 0. 1 = enabled

    3. Book 0 Page 0 register 0x1B bit 0. 1 = enabled

    4. default scripts are provided in section 10 of the TAS2781 datasheet. 

  • 0
    Prodigy 30 points

    Thank you for your reply.

    1. What exactly does ROM mode mean? Why is protection disabled in ROM mode?

    2. Can the BOP reduce output even in a power supply environment?

  • 0 in reply to Jaesung Kim
    TI__Mastermind 22035 points

    Jaesung, 

    1. ROM Mode means the DSP is disabled. the name "ROM mode" means the DSP is running of the Default ROM configuration, which is DSP bypass/disabled. 

    2. BOP is triggered off the supply voltage. (either PVDDL or PVDDH based on the BOP_SRC register). in the power supply is below the threshold which is 2.9V by default. section "8.4.2.10 Brownout Prevention" of the datasheet explains all this in detail. 

    It seems like you are unable to get the correct peak voltage out. 

    the default scripts, in section 10 of the datasheet, will be able to give peak output voltage. 

    If you are using the EVM + PPC3. then you can program the device into ROM mode by navigating to the "device control" panel in PPC3, selecting "ROM Mode" and pressing "Apply"

     Regards,

    Arthur