Has anyone used TDA7468 or friends? - diyAudio
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Old 5th November 2011, 04:54 AM   #1
vkj is offline vkj  India
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Default Has anyone used TDA7468 or friends?

I am trying to use the TDA7468 for a simple preamp. The part was obtained from digikey.

After soldering it up and driving it, there is no output. The output dc is 1/2 the supply, but there is zero signal. I can tell that the i2c routines are working because (a) I get an ack, and (2) I am able to switch the input source correctly. The input source is available at the mux output of the amp. I can also switch the gain as per the specs. But the signal doesnt seem to be getting past the volume and tone control stages. I tried different setting for the mute function but nothing works. Same with the volume.

The (badly written) datasheet doesnt say what the power-on settings are. It has some table giving a power on reset input code, but I have no idea how this is used.

Has anyone used this or the other chips of the same type? ANy ideas how to fix this problem?

Thanks,

vkj
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Old 6th November 2011, 06:13 AM   #2
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Mute Off = Output On.

Volume1 and Volume2 must be set on both channels. So there are four settings for the volume control: Volume1 setting 1, Volume2 setting 1, Volume1 setting 2 and Volume2 setting 2. Volume 1 is before tone control, Volume2 after tone control, setting 1 means channel 1 and setting 2 means channel 2.

You can find the Power-On Reset Condition in Table 5.
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Old 7th November 2011, 03:10 AM   #3
vkj is offline vkj  India
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Quote:
Originally Posted by pacificblue View Post
Mute Off = Output On.

Volume1 and Volume2 must be set on both channels. So there are four settings for the volume control: Volume1 setting 1, Volume2 setting 1, Volume1 setting 2 and Volume2 setting 2. Volume 1 is before tone control, Volume2 after tone control, setting 1 means channel 1 and setting 2 means channel 2.

You can find the Power-On Reset Condition in Table 5.
Thanks for your reply.

I did try both mute off and mute on (Table 14, sub-address 6, value 1/0). Didnt make any difference.

I tried a volume setting of 0 for L and R channels, which I assume is "full" volume, 0dB, acc. to the table. Am I right?

I dont understand Table 5. It is not referred to in the text. Is it a one-byte command to reset the chip? If so what is the reset setting?

Thanks

vkj.
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Old 20th September 2013, 08:00 PM   #4
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VKJ, have you had any luck with this? I saw this part and really would like to use it however, after reading ST's so called datasheet (extremely vague and lacking of anything useful) I am a bit apprehensive.

Pacificblue do you happen to have a working schematic with this part? I found a service manual with this part in it but I'd like to have a second reference.
Thanks guys!
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