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[ TAS5421-Q1 ] SpeakerGuard

Kenichiro
Mastermind 9165 points
Other Parts Discussed in Thread: TAS5421-Q1, TPA2015D1, TPA3116D2

[ TAS5421-Q1 ] SpeakerGuard

Hi,

Can you help me to address following discussion with customer on SpeakerGuard of TAS5421-Q1?

<Q1>:
Can you elaborate the theory of operation of SpeakerGuard?

From datasheet description, it is described that the output amplitude is limited by this feature, however, in the block drawing, the box of SpeakerGuard is located in between preamp and PWM modulator and not directly monitor the output amplitude.

Does this mean that SpeakerGuard block approximate the output amplitude based on the input amplitude, Gain setting, preamp gain and gain of PWM modulator block, then control gain?

<Q2>:
The SpeakerGuard just limit the gain, but does not “Clip” the output amplitude. Correct?

<Q3>:

Since SpeakerGuard is kind of “protection feature” and not fault detection feature,
so, this means, even though SpeakerGuard is activated…
- FAULT pin is not triggered
- No status register updated

And then, once the situation removed, SpeakerGuard is deactivated automatically.
Is my understanding correct? I took drawing from TPA2015D1.

<Q4>:
The output amplitude is limited by SpeakerGuard, this basically means the duty cycle of output signal is limited.
So, if SpeakerGuard is set by register, the duty cycle of output is never reached to 100%.
Correct?

Thanks,

Ken

  • 0
    TI__Mastermind 35855 points
    Ken, Q1 and Q2: The TAS5421 speakerguard is a simple voltage limiter as described in the datasheet. The voltage thresholds are controlled in an I2C register. The output signal is clipped at the peak voltages listed in register 0x03 in the TAS5421-Q1 datasheet. It is not dependent on the power supply voltage. Q3: The fault pin is not triggered and no indication will be given in the I2C registers. The speakerguard in the TAS5421 is more like the PLimit in the TPA3116D2. It not like the limiter in the TPA2015D1. Q4: Correct.