TAS5805M: TAS5805M Analog Gain Setting

C%20K%20Ong

Part Number: TAS5805M
Other Parts Discussed in Thread: TAS5805,

Hi,

We used TAS5805 with PVDD=5V.

We tried to set Analog Gain at Register 0x54=0x1F, and Analog Gain vis PPC3’s TAS5805M GUI to -15.5dB. However this was unable to limit the output voltage to the level we needed for AGL.

Ended up, we have to set AGL Threshold to -19dB in order limit the output voltage (ideally we only need to set AGL Threshold to -3 to -4dB).

Please advise what else we need to configure to get this Analog Gain work.

over 4 years ago

0 Xiaolin Qin over 4 years ago

TI__Expert 6295 points

hello

could you please provide more details of your PVDD, load and output target & THD etc. Also its good to share all what your register setting to give us overview what is problem during setting.

regards

Linda

0 Matthew Miao over 4 years ago

TI__Expert 6720 points

Hi,

It seems Analog Gain setting does not work. Please use -20dB 1kHz sinewave to measure output level while analog gain switching.

5V PVDD situation, -15.5dB analog gain / 0dB or -1dB AGL should be able to avoid both digital and analog clipping.

Regards,

Matthew

0 C%20K%20Ong over 4 years ago in reply to Matthew Miao

Expert 1240 points

Hi,

Please find attached PPC3 configuration file.

Requirements:

PVDD = 5V

Speaker = 4ohm.

Output Power = 1.5Wx2 @ THD<1% for discrete tone, 1.8Wx2 @ THD<1% for music.

When playback -20dB Sinewave with PC volume = 100%, and change Analog Gain from 0dB to -15.5dB, the playback audio loudness did not change.

0 C%20K%20Ong over 4 years ago in reply to Xiaolin Qin

Expert 1240 points

Hi Linda,

File attachment function not working . I can not attach the PPC3 file.

0 Matthew Miao over 4 years ago in reply to C%20K%20Ong

TI__Expert 6720 points

Hi,

It's the key point that loudness does not change after Analog modification, which means analog configuration is not successful. Do you use EVM board for testing? How did you change analog gain? By using I2S script or PPC3?

If using I2C, whether register Book and Page script is added:

w 58 00 00

w 58 7f 00

w 58 54 1f

Regards,

Matthew

0 C%20K%20Ong over 4 years ago in reply to Matthew Miao

Expert 1240 points

Yes, I used the EVM to test.

I used the Analog Gain setting in the PPC3 GUI to set the gain. Then, I went Register Map to check if register 0x54 changed accordingly.

My colleague have another boards, but seemed to look different from my board (we based in different Countries). His board seems to response to Analog Gain, but behaviour is also very strange. We are still troubleshooting.

For his boards configuration:

PVDD =5V

Speaker = 4ohm

Test Signal =1KHz

EQ Gain at 1KHz = 0dB

Analog Gain = 0dB

Volume = -11dB

Mid DRC Region 1 Threshold -21.5dB Offset 0dB. This supposed to have sensitivity @ -6dB signal

Region 2 Threshold -3dB Offset -14.5dB

He got 1.2W @-6dB signal , and 1.8W @ 0dB.

0 Matthew Miao over 4 years ago in reply to C%20K%20Ong

TI__Expert 6720 points

Hi,

The behavior of DRC is effected by crossover band and the response is not flat. It's recommended to use AGL for first round output power limitation.

You can refer below TAS58xx general tuning guidance.

http://www.ti.com/lit/an/slaa894/slaa894.pdf

Regards,

Matthew

0 C%20K%20Ong over 4 years ago in reply to Matthew Miao

Expert 1240 points

Dear Matthew,

Yes, we are aware the DRC Response at crossover frequency is not flat. We changed the crossover frequencies of adjacent DRC further apart to make it flatter.

Our issue is not DRC, but Analog Gain.

0 Matthew Miao over 4 years ago in reply to C%20K%20Ong

TI__Expert 6720 points

Hi,

If DRC is changed to make flat, then there is no problem with your colleague board. Right? I supposed analog gain only doesn't work with your board. Then it's suggested to try another PC to connect with your board.

Regards,

Matthew

0 C%20K%20Ong over 4 years ago in reply to Matthew Miao

Expert 1240 points

We change to another TI EVM.

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TAS5805M: TAS5805M Analog Gain Setting