TDA1554Q Features

[Wilson2004]

Hi members...I want to build a simple car radio and use the TDA1554Q but some features are not clear for me:
1) Difference between GROUND(signal)-PIN 3 and POWER GROUND(substrate)-PIN 7 and 11.
In this case do I need to provide two separated GROUNDS on the PCB and use two wires, one for the POWER GROUND and another for the GROUND SIGNAL, both connected to the car chassis?
2) "No switch-on/switch-off plop", what means this feature?

Thanks for any comment.
Wilson

[Evan Shultz]

Wilson,

1. no, there is no difference. you can connect pins 3, 7, and 11 together safely. it's best to connect them at a single point as a star ground, however. i'd suggest bringing the input signal grounds to pin 3 and the power ground to pins 3 and 7. then either connect them with a small trace between pin 3 and either pin 7 or 11 or else connect them together at the input for the power supply.

2. it means that the amplifier supposedly will not 'pop' [not plop] through the speakers at start-up and shut-down.

regards, Evan

[carlosfm]

I have a 4-channel amp in my car with those chips, I made it with two of them, 20w RMS and very good.
It has a standby feature that works very well, no need for relays.
Don't ask me too many details, I made this some years ago, don't remember...

[Wilson2004]

Carlos,
Do you have the schematic? I would like to see the standby feature of your amp.

[carlosfm]

Originally posted by Wilson2004
Carlos,
Do you have the schematic? I would like to see the standby feature of your amp.

No schematic.
It's all in the datasheet.

[Wilson2004]

I finished the tests with my AM/FM Radio for car, I used a simple AM/FM turner built with TA2003 IC.
For tone controls it uses a LM1036 and two TDA1554Q amplifiers.
It's a prototype, I don't have a PCB now but I'll start it soon.
It's working well, the only problem is the "pops" through the speakers at shut-down. When I turn on the radio there is no "pops", it's OK.
I did the schematic and it can be downloaded at:
http://wilsonmartinez.bravehost.com/...schematic.html
I'm not an electronic engineer and really don't have much experience in audio, it have beeing a hobby for me.
Hence, any help or any comment, I will be very thankful.
(I Need to improve my English )

[carlosfm]

Are the "pops" too loud?
Mine makes some "pops" at power-on, and no noise at power off.
I never bothered with that, it sounds good, and I have no time in the next years for car-audio again.

[Wilson2004]

Carlos,
The "pops" are not too loud, I wish I could eliminate it but I can use the radio with pops.
I also tested the circuit suppling +12V to the amp and separating the rest of the circuit with a switch. When I turned it on the pops was still there, really not the best solution.
SPEAKERS:
The car speakers are 4x 25W-4ohms, they are old and small, I really though I would get a good sound at 50% of the volume pot, but I have to put it in 80% when the driving the car (because motor sound).
Is something wrong with my amplifier? Or 20W per channel is not too much? Or the speakers must be updated?
AUX IN:
I got disappointed when I connected my Sony Mini Disk at the aux in, the sound was too much low and I don't have any idea in how to increase aux in level....please members, give me an idea.
the schematic: http://wilsonmartinez.bravehost.com/...schematic.html
Thanks for any comment,
Wilson

[carlosfm]

Originally posted by Wilson2004
SPEAKERS:
The car speakers are 4x 25W-4ohms, they are old and small, I really though I would get a good sound at 50% of the volume pot, but I have to put it in 80% when the driving the car (because motor sound).
Is something wrong with my amplifier? Or 20W per channel is not too much? Or the speakers must be updated?
AUX IN:
I got disappointed when I connected my Sony Mini Disk at the aux in, the sound was too much low and I don't have any idea in how to increase aux in level....please members, give me an idea.
the schematic: http://wilsonmartinez.bravehost.com/...schematic.html
Thanks for any comment,
Wilson

These chips have fixed gain.
Actually, with my radio it plays too loud, the volume is always at the minimum.
I have a portable CDP, that I connect to the aux. in, and of course it plays at a lower level (unavoidable with portable gear), but curiously this level is right, it's not too high as when listening to the radio.
The problem you have is not the amp, it's just that the pre outs of your radio unit are too low in level.