TAS5760M: PK_OUTA +/- or SPK_OUTB +/- is open

Shuji Ishiwata

Part Number: TAS5760M

Hi　Team,

I have a question about TAS5760M.

The configuration is as shown in Fig. 66 of the data sheet.
When only the speaker in this figure was removed, the SPK_FAULT pin became Low.
In this case, what is the error?

Is it an error when SPK_OUTA +/- or SPK_OUTB +/- is open?

Best Regards,
Ishiwata

over 4 years ago

0 Sadanori Kato over 4 years ago

Guru 36490 points

Hi Ishiwata-san,

I think that the the OTE is detected due to the LC resonance phenomenon without the load impedance, so please observe SPK_OUTA+/- and SPK_OUTB+/- with the oscilloscope.

Best regards,
Kato

0 Matthew Miao over 4 years ago

TI__Expert 6720 points

HI Ishiwata,

What's your output inductor / cap value, and PWM switching setting? Lower PWM switching + small inductor / cap will easily trigger over-current fault.

It's also suggested to change to larger inductor to test. Such as 15uH or 22uH + 0.1uF.

Regards,

Matthew

0 Shuji Ishiwata over 4 years ago in reply to Matthew Miao

Genius 5875 points

Hi Matthew-san

Thank you for your reply.

The customer's LC is 22 μH and 2.2 μF.
The cause is likely to be different.

Best Regards,
Ishiwata

0 Matthew Miao over 4 years ago in reply to Shuji Ishiwata

TI__Expert 6720 points

Hi Ishiwata,

22uH + 2.2uF will cause large Q at audio bandwidth. TAS5760 is closed loop class-D, so it's suggested to use 10uH + 0.68uF.

Please change LC to check SPK open issue again.

Regards,

Matthew

0 Shuji Ishiwata over 4 years ago in reply to Matthew Miao

Genius 5875 points

Hi Matthew-san

Thank you for your support.

I ask the customer to be set to LC 10uH / 0.68uF.

Best Regards,
Ishiwata

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TAS5760M: PK_OUTA +/- or SPK_OUTB +/- is open