TDA1543 problems

[lasso]

Re: Compliance.

According to the schematic the i/v resistors are 887R each and the reference resistor is 1K
From the above Iref is (Vref/1K)xAIbias = (2.2/1000)x2=4.4mA
This is then added to the output current. The fullscale output current for each output is 2.65mA and added to Ibias yields a total of 7.05mA per output. Full scale output voltage is 7.05mA x 887R = 6.25V. This seems a little. It makes a mockery of the compliance limits of the chip and the V+ rail is only 5volts. Perhaps you should reconsider some of the resistor values.

When I was pondering this, I found this interpretation that seems logical: how to calculate the I/V stage .

What values would you recommend instead? As the datasheet is not overly pedagogic, of course there may be misinterpretations floating around (including mine).

 

[rfbrw]

Re: Re: Compliance.

When I was pondering this, I found this interpretation that seems logical: how to calculate the I/V stage .

What values would you recommend instead? As the datasheet is not overly pedagogic, of course there may be misinterpretations floating around (including mine).

The TDA1543 is supposed to operate into a virtual earth. If you choose to ignore the datasheet a go with this passive iv lark, you can't complain when it all goes wrong. The opamp based iv in the datasheet works but if you insist on passive iv you could try upping Rref from 1k to around 3k9.

 

[lasso]

Re: Re: Re: Compliance.

The TDA1543 is supposed to operate into a virtual earth. If you choose to ignore the datasheet a go with this passive iv lark, you can't complain when it all goes wrong. The opamp based iv in the datasheet works but if you insist on passive iv

Nah, not really complaining (at least I hope it doesn't seem like that), and I'm not really insisting on passive I/V either. (In fact, I already have all the parts for the active I/V from the datasheet.)

My reason for passive I/V is because it's what "everyone" seems to be using. But on the other hand, very few seem to power the TDA1543 with only 5V, most use higher voltages and they also stack the chips.

I might try 8V just for the sake of it, using values from some of the schematics off the net, before going for the opamp I/V as you're suggesting.

you could try upping Rref from 1k to around 3k9.

Should the I/V resistors then stay the same at ~900 Ω?

And, does this mean that the method for calculating the restors in Kuei Yang Wang's post (that I linked to) is incorrect?

 

[lasso]

My TDA1543 dac is perfectly working but switch channels. And it inverts the signal and should do so.

Hm, on closer thought I've seen somewhere that it's supposed to invert the signal, but should it really switch the channels as well? Why haven't Philips just swapped the right and left in the datasheet then?

Check that the voltage is close to 2.8VDC (this is important)
at the outputs when no signal is applied. This is valid for +5V supply voltage.

Aye, noted. I take it that you're running your DAC on 5V? What values are you using for the three output resistors?

 

[rfbrw]

Re: Re: Re: Re: Compliance.

The final values of Riv at 2k4 and Rref at Ik5 are correct for the scenario he outlines i.e V+ at 8v.

 

[Carl Ekblom]

haven't Philips just swapped the right and left in the datasheet then?

yes, the datasheet isn´t correct here

Aye, noted. I take it that you're running your DAC on 5V? What values are you using for the three output resistors?

I´m running the dac at 8V with 2k output resistors and a adjustable resistor for the current sink. The calculations in the link you submitted is as far as I see it correct. Your schematic is OK.

Carl

 

[Igla]

This calculations for I/V are close.But isn't more easy to connect the scope at the output and adjust Rref, so the DAC won't clip.
I also run TDA1543 on 5V; my I/V resistors are 1k and according to my scope Rref must be between 900ohm and 1100ohm or the DAC clipps.As simple as that.
Am I missing something?

Regards;
Igla

 

[Carl Ekblom]

haven't Philips just swapped the right and left in the datasheet then?

yes, the datasheet isn´t correct here

Aye, noted. I take it that you're running your DAC on 5V? What values are you using for the three output resistors?

I´m running the dac at 8V with 2k output resistors and a adjustable resistor for the current sink. The calculations in the link you submitted is as far as I see it correct. Your schematic is OK.

Carl

 

[rfbrw]

In the belief that self-flagellation is good for the soul, I just put one of these TDA1543 dacs together. Riv 750R and Rref 1k. Alas, it works. Channels are correct in line with the datasheet and no nasties. Will hit it with 0dB and see what happens.

 

[lasso]

In the belief that self-flagellation is good for the soul

I just put one of these TDA1543 dacs together. Riv 750R and Rref 1k. Alas, it works. Channels are correct in line with the datasheet and no nasties. Will hit it with 0dB and see what happens.

This is most interesting. Do you see any major differences vs my schematics?

My datasheet has the right channel on pin 8, is that what yours has as well? Also, is your outsignal inverted or not?

 

[Elso Kwak]

Self-flagellation????

Self-flagellation????
Well, well this forum keeps surprising me!
What's next? Self-humilation?

 

[rfbrw]

This is most interesting. Do you see any major differences vs my schematics?

A CS8412 and minor variations in the TDA1543 resistor values aside, there are no differences.

My datasheet has the right channel on pin 8, is that what yours has as well? Also, is your outsignal inverted or not?

Right channel is on pin8 and the phase ident signals seem alright. As for the sine wave, can't see how one can tell whether it is inverted or not. Its off a test disc.

 

[Elso Kwak]

Right channel is on pin8 and the phase ident signals seem alright. As for the sine wave, can't see how one can tell whether it is inverted or not. Its off a test disc.

Use a testdisc with a needle signal. Not that I hear any difference; must be my old ears....

 

[rfbrw]

Good idea, I'll try that later. There is only so much of the TDA154x stuff I can take and still remain sane.

 

[Elso Kwak]

Jim Hagerman wrote a paper why NON-OS is bad. Must sound like music to your ears rfbrw!
http://www.hagtech.com/pdf/not16bit.pdf
He cancelled his NON-OS TDA1543 DAC. It had some interesting circuit details though...

 

[rfbrw]

He definitely tried his best to make the pig fly but no deal. After 30 minutes of the TDA1543 this morning, it will probably take another day or two of continuous Lemonjelly and Orbital in the player to recover and I will have to build something else to cancel out the negative karma that came from building the TDA1543 dac.