I needed a simple stereo amplifier, working on a 12Vdc power supply, and naturally choose TDA1557 audio amplifier.
The typical circuit is very simple. I have followed the datasheet carefully, but my circuit does not work:
- when the pin12 (Vref) is not connected, the circuit starts to "pump" a lot of current (more than 2 amps) , and although there is no input signal, a loud random noise happens on the speaker
- when i connect this pin to the GND, supplied current seems more reasonnible, but nothing is happening (input signal is not amplified, no output signal).
I am sure that your circuit will work even if you do not connect the Vref pin(let it free)
I guess that the problem is due to 'MUTE' and STAND-BY switch(pin 11).
connect that pin to VCC through a 82K resistor and with a 22uF capacitor to ground.
I am pretty sure your problem would be solved if you do so
If I made no mistake, this RC combination gives a 1.8s power-on delay.
Why do you think this will solves my problem ? Have you experimented this solution yourself ?
I really hope it will solve my issue anyway...
I will try this this monday, cause my circuit is at my workplace, so no test this WE
I noticed that you told that the circuit draws 2 Amps Without connecting the Vref.
I have made several amplifiers using that chip. The Vreff pin was not connected for none of them and I had NO problem at all (I used two of those amplifiers in a home made radio and they worked just fine). If your circuit draws 2 amps without any input so maybe your chip is fried? or maybe you have a problem with wrong wiring?
If you are sure that your chip and wiring are fine, just let me know to put my
schematic here(that chip has just 7 or 8 components for biasing, so you can handle it easily)
besides, yes that RC circuit is there for producing a small delay, but you have to bias the MUTE pin with VCC (the resistor does that job too) and don't use the said capacitor to get any delay(that's what I have done for one of my amplifiers)
I had a look at your PCB, and understood all (3 components, easy).
you are right, it seems compatible with 1557Q, so I will try this on Monday.
I will then let you know the results.
You must read a datasheet carefully when it is for a car radio amplifier.
The TDA1557 and most other amplifiers are rated at 22 Whats per channel into 4 ohms with a 14.4V supply. Whats are produced when the volume control is turned up way too high so the output is a horribly distorted square-wave.
The TDA1557 is rated at 12 Watts RMS per channel into 4 ohms at clipping with a 13.2V supply. When the supply is only 12V then the output power is much less.
When the speakers are 8 ohms then the power is halved.
Don't use electrolic caps as the input capacitor. I once did this with that amp IC and it caused it to do all sorts of strange stuff.Use poliester and such caps for that. The Vref cap is recommended for single eded mode configuration to reduce noise. But you must be using bridge configuration since it doubles the power and halfs the 4 channels in to 2
I have read carefully datasheet, triple-checked wiring, and this amplifier is still not working.
So I have ordered new IC, but this time I will go with TDA1554. I guess the silicium design is not very different from the TDA1557, but it does not have this Vref pin, which from the beginning, i am wondering what this pin is for, and for which i did not get clear info on what to do with it.
Do you guys have some advices to give for this TDA1554?
Don't use electrolic caps as the input capacitor. I once did this with that amp IC and it caused it to do all sorts of strange stuff.Use poliester and such caps for that. The Vref cap is recommended for single eded mode configuration to reduce noise. But you must be using bridge configuration since it doubles the power and halfs the 4 channels in to 2
I have read carefully datasheet, triple-checked wiring, and this amplifier is still not working.
So I have ordered new IC, but this time I will go with TDA1554. I guess the silicium design is not very different from the TDA1557, but it does not have this Vref pin, which from the beginning, i am wondering what this pin is for, and for which i did not get clear info on what to do with it.
Do you guys have some advices to give for this TDA1554?
i was also wondering and i was creating new topics on forums so i can learn...
don't waste your time thinking what to do with the Vref, this amplifier is very simple.
recomended value for the input capacitors is 220nF and a 100nF for decoupling on the power rails... assuming that your power supply has
enough smoothing capacitance.
the pcb i posted makes your life easy, but if you want to go on with the TDA1554 it's your decision.