need help on TDA1541a power supply.

tone · 2nd March 2003, 07:42 PM

hi all,
since i build the dac power supply without the dac chip on board.
tested result +-5 volts was ok..-15volts was ok..on the spot..
but when i plug in the dac chip..
the tda chips eats 5volts from my -15volts power supply!!.why?
+-5volts was ok...is it normal>? or i need to crank up the supply?

>pls help.
>have attach the circuit.
>
>thanks.

>rgds
>tone

Elso Kwak · 2nd March 2003, 08:08 PM

Hi tone,
As I see it you are using exactly the component values used by Thorsten Loesch in his Adagio DAC. Thorstens schematic is hard to read due to low resolution but I guess you are right with the values. The output of the regulator is (1+ 5.1/1)x 2.5= 15.25 V.
The ony clue I have is that your TDA1541 has a shortcircuit for the negative supply. Did you try an other chip?. Does it get more than handwarm? What is the voltage before entering the TL431?

ashok · 3rd March 2003, 01:48 AM

This may sound silly, Tone.
If you are using a breadboard or brand new board design ,are the supply pin connections correct.
If its a regular (tried) board it must be something else of course.
I'd hate to loose a TDA1541 !
Cheers.

Art · 3rd March 2003, 04:36 PM

Please check TL431. I don't sure it's still alive.
You feed -24V and need -15, so 9V drop on the 68R. You tested the PS by unpluged 1541, so at that time ~130mA drain through TL431 which is 30% higher than max rating. TL431 may went to hell already.

I feed just -18V and R drop at 39 ohm. TL431 will drain only 76mA even 1541 out of socket, Safe.

Hope this help.

Art · 3rd March 2003, 04:41 PM

Well, just remind. How did you make -24V? Some series regulator such LM7924 or LM337T, has been used. It may be oscillate if you didn't put 1uF at the output of those regulators.
This was happen to me once. I connected LM337T output directly to TL431 set without C inbetween. It was oscillate. The Vout of TL431 will drop anytime I connected load, but seem work normally without load.

Hope this help too

Elso Kwak · 3rd March 2003, 05:02 PM

Hi,
tone mailed me the problem is solved.
As it seems all supplies have to be connected to the TDA1541 to work properly!

deskmate88 · 19th March 2003, 02:36 AM

I am new to the TL431, can some one help me to locate the application notes on how to use the TL431 as a shunt regulator, the data sheet does not say much.

What's the relationship between the current, supply voltage and output voltage?

Many thanks.

2nd March 2003, 08:08 PM	#2
Elso Kwak Banned Join Date: Dec 2001 Location: Zamboanga, City of Flowers, Mindanao	Powersuppy Problem Hi tone, As I see it you are using exactly the component values used by Thorsten Loesch in his Adagio DAC. Thorstens schematic is hard to read due to low resolution but I guess you are right with the values. The output of the regulator is (1+ 5.1/1)x 2.5= 15.25 V. The ony clue I have is that your TDA1541 has a shortcircuit for the negative supply. Did you try an other chip?. Does it get more than handwarm? What is the voltage before entering the TL431?

3rd March 2003, 01:48 AM	#3
ashok diyAudio Member Join Date: Jun 2002 Location: 3RS	Pin connections This may sound silly, Tone. If you are using a breadboard or brand new board design ,are the supply pin connections correct. If its a regular (tried) board it must be something else of course. I'd hate to loose a TDA1541 ! Cheers. __________________ AM

3rd March 2003, 05:02 PM	#6
Elso Kwak Banned Join Date: Dec 2001 Location: Zamboanga, City of Flowers, Mindanao	Solved! Hi, tone mailed me the problem is solved. As it seems all supplies have to be connected to the TDA1541 to work properly!

19th March 2003, 02:36 AM	#7
deskmate88 diyAudio Member Join Date: Jan 2003 Location: Asia	new to TL431 I am new to the TL431, can some one help me to locate the application notes on how to use the TL431 as a shunt regulator, the data sheet does not say much. What's the relationship between the current, supply voltage and output voltage? Many thanks.

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3rd March 2003, 04:36 PM	#4
Art diyAudio Member Join Date: Oct 2002 Location: Thailand	Please check TL431. I don't sure it's still alive. You feed -24V and need -15, so 9V drop on the 68R. You tested the PS by unpluged 1541, so at that time ~130mA drain through TL431 which is 30% higher than max rating. TL431 may went to hell already. I feed just -18V and R drop at 39 ohm. TL431 will drain only 76mA even 1541 out of socket, Safe. Hope this help.

3rd March 2003, 04:41 PM	#5
Art diyAudio Member Join Date: Oct 2002 Location: Thailand	Well, just remind. How did you make -24V? Some series regulator such LM7924 or LM337T, has been used. It may be oscillate if you didn't put 1uF at the output of those regulators. This was happen to me once. I connected LM337T output directly to TL431 set without C inbetween. It was oscillate. The Vout of TL431 will drop anytime I connected load, but seem work normally without load. Hope this help too

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