Oscillating TDA7293

[CesarMarzoa]

I've build up the tippical application circuit for TDA7293 as the datasheet puts, but when I power it on, it oscillates! I tried putting an RC network at output as the modilar application shows ( in the same TDA7293' datasheet), but it did not fixed the problem, it still oscillates... does anybody knows why?

 

[gophert]

I've build up the tippical application circuit for TDA7293 as the datasheet puts, but when I power it on, it oscillates! I tried putting an RC network at output as the modilar application shows ( in the same TDA7293' datasheet), but it did not fixed the problem, it still oscillates... does anybody knows why?

A schematic of your circuit and a photo of your project would be great help. It sounds like a wiring should be checked first for errors. Also, a list of deviations from the published schematic.

 

[audioguru]

If you built the amplifier on a solderless breadboard then the stray capacitance between the many rows of contacts and the many long wires all over the place will couple feedback.

 

[crutschow]

Is the chip power decoupled to ground at the chip pins?

 

[dr pepper]

Your power supply might not be beefy enough, is the oscillation super audio or is it motorboat type noise.

 

[AnalogKid]

No schematic, no clear answers. But ... audio power amplifier chips are notorious for breaking into oscillation, and are super-sensitive about power supply decoupling.

ak

 

[CesarMarzoa]

Thank you all guys! The problem was I didn't used the supply pins' 1000uF capacitor . I'm actually repairing a solid state amp, and I thought using the amp's power source 4700 uF caps would be enough to supply my TDA, but those were just not enough. As soon as I placed the 1000uF caps on my PCB the noise dissapeared!

 

[crutschow]

Thank you all guys! The problem was I didn't used the supply pins' 1000uF capacitor . I'm actually repairing a solid state amp, and I thought using the amp's power source 4700 uF caps would be enough to supply my TDA, but those were just not enough. As soon as I placed the 1000uF caps on my PCB the noise dissapeared!

It's not that the 4700 μF caps weren't big enough, it's that they were too far away, and the lead inductance in between prevented them from providing a proper decoupling for the TDA.

 

[dr pepper]

There might be a zobel network fitted, a series cap and resistor on the o/p of the amp, if there is one check the devices, and instable amp usually fries these parts.