TAS5805M: Audio output stops after few seconds and Fault triggered

Manikandan Janakiraman1

Part Number: TAS5805M
Other Parts Discussed in Thread: TAS5825M,

Due to supply issue we are switching our woofer amp TAS5825M to TAS5805M and we are mocking few units with TAS5805M part. During bring up we are seeing below issue

1. Woofer works for few seconds (<10sec) at low volume level <30% and then it stops working no woofer output (I2C works fine but Fault pin triggered). We did checked the fault registers every time the issue happened one or two fault registers are set

0x70 -> 02 or 03 (Over current)

0x71 -> 04 (clock fault) - There should not be any clock fault because we have this TAS5805M driver is working with similar other product using TAS5805M

0x72 -> 01 (over temperature ) - Over temp fault is happening most of the time but I did checked the chip temp but I don't see it is very hot.

2. If the volume level is set more than 60%, the woofer output stops from the start and it doesn't play for few seconds. During this case we are seeing same OT and clock fault but I dont think chip will reach max temperature as soon as it starts playing.

Can you help debug this issue?

Thanks
Mani

over 4 years ago

0 Luis Fernandes de Pina over 4 years ago

TI__Genius 15120 points

Hello Mani,

Can you provide the init sequence when you are starting up the device and going from the idle/sleep state to play.
Also do you have waveforms of when this OC shutdown is happening as you are ramping up with volume?
Can you provide a waveform of the PVDD line?
What audio are you using for the test, is it a sine tone at a specific frequency or a song file?

Best regards,

Luis

0 Manikandan Janakiraman1 over 4 years ago in reply to Luis Fernandes de Pina

Prodigy 110 points

Hi Luis,

1. I am working with our SW team to get the init sequence. I will post it once i have them. The same SW working with our other product with same amp config.

2. I don't have waveform of OC shutdown. I personally didn't see the OC problem and my colleague saw this with his unit.

3. Attached the waveform. I don't see any peak or drop, volume level was kept very low but woofer stopped working after few seconds due to OT.

4. I am playing some random song from youtube or iheart radio.

Most of the time the fault triggered by OT. Is there a register where we can read the device temp?

Thanks

Mani

0 Luis Fernandes de Pina over 4 years ago in reply to Manikandan Janakiraman1

TI__Genius 15120 points

Hello Mani,

What modulation scheme is being used !SPW?BD? Hybrid? Is the issues being encountered across multiple modulation schemes? There isn't a register outside of the OTW fault to see temperature. Is possible to see the device temperature using a thermal camera or a similar such device to see how the IC and board in heating up during operation?

Please let me know when the SW sequence can be provided.

best regards,

Luis

0 Manikandan Janakiraman1 over 4 years ago in reply to Luis Fernandes de Pina

Prodigy 110 points

Hi Luis,

We are using Hybrid modulation. I will try to get the temperature by thermal camera or thermocouple.

Here is a short summary of init sequence during power-up:

pulling up PDN gpio

wait for 5ms

enable clocks

send init sequence (FW)

mask CLK interrupts (to prevent message flood into some corner case as I remember)

Set PBTL mode (for woofer amp. This is important, and could lead to OC and OT events, if not active for amp with speaker wired PBTL mode)

Set gpio config (for faultz Interrupt)

put amp into sleep mode

disable clocks

On playback session

tas58xx_startup()

tas58xx_prepare()

we just unmute amp, set it into play mode and send data.

After it finishes

tas58xx_shutdown()

mute, and return back to sleep.

Thanks

Mani

0 Luis Fernandes de Pina over 4 years ago in reply to Manikandan Janakiraman1

TI__Genius 15120 points

Hello Mani,

The startup sequence needs to be modified I believe. Please refer to TAS5805M datasheet 7.4.6.3 Hybrid Modulation has specific recommendations in the init/toggle sequence that needs to be followed to prevent possible faults.

This has been relayed to members of different teams at your company in a previous support case. Can you contact the field engineer assigned to your account and we can follow up on this support case in more detail via email if with this sequence modification the system still has issues?

best regards,

Luis

0 Manikandan Janakiraman1 over 4 years ago in reply to Luis Fernandes de Pina

Prodigy 110 points

Hi Luis,

Let me check with team and let you know whether the proper sequence is implemented or not.

Thanks

Mani

0 Luis Fernandes de Pina over 4 years ago in reply to Manikandan Janakiraman1

TI__Genius 15120 points

Hello Mani,

Thank you, will wait for your response.

Best regards,

Luis.

0 Manikandan Janakiraman1 over 4 years ago in reply to Luis Fernandes de Pina

Prodigy 110 points

Hi Luis,

I did got a confirmation from team that TI recommended sequence is implemented in design.

Looks like these faults are happed due to the rework or mockup. Reworked amps don't have proper component placement and heat dissipation path. Now we have installed the chip in a properly designed board and all the faults are gone. 30mins play test passed without any problem.

I do have a question about the LC combination at the output of amp (refer the schematic in my initial post). Right now we are using 4.7uH+1uF and we are seeing almost 3.92A startup current at OUTA. OCP limit is 5A so we have 1A margin. But the TI recommendation is above 15uH and 0.68uF. Do you have any concern?

Thanks

Mani

0 Manikandan Janakiraman1 over 4 years ago in reply to Manikandan Janakiraman1

Prodigy 110 points

Hi Luis,

Do you have any update about the LC combination at the output?

Thanks

Mani

0 Dylan Yao over 4 years ago in reply to Manikandan Janakiraman1

TI__Genius 10830 points

Hello Mani,

Hope this thread information can help you.

https://e2e.ti.com/support/audio-group/audio/f/audio-forum/822127/tas5805m-how-to-calculate-the-peak-current-of-filter-inductance-at-the-output-end-of-digital-power-amplifier/3058850?tisearch=e2e-sitesearch&keymatch=%20user%3A351571#3058850

Dylan

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TAS5805M: Audio output stops after few seconds and Fault triggered