Problems connecting RL=8 Ohm to the circuit TDA8950 BTL

DORONV

Member
2013-04-21 10:25 am
Need help and advice.
I built a Class D amplifier based using the TDA8950 component. The circuit was built as a BTL amplifier.
The circuit is connected and works with a ±30V symmetric power supply
When connected to load RL = 8 ohm the circuit stops working,
for a load of about RL = 20 ohms The circuit is working properly.
Can't find the reason, though I checked all the protection topics including
"Output current limit".
Thanks to someone can help me.
 
A couple of investigative tricks:
Measure the DC offset between the outputs without signal and the 20R as load. It could be an offset that makes the chip detect a DC and as consequence disable the power stage.
Try each output separately with a 2200uF capacitor in series with the 8 Ohm load, capacitor "+" toward the output line and "-" toward the 8 Ohm speaker, other end of 8 Ohm speaker connected to power supply "-".
 

DORONV

Member
2013-04-21 10:25 am
Thanks for the advice given.
I tried but the situation even got worse.
Certainly, one of the defenses is activated, everything is checked and nothing found.
Another suspicion of mine is that the cause of the problem may be the supply of voltages and ground to the component circuit.
Does anyone know if TDA8920 replaces 100 percent to TDA8950 ?, I thought to try and assemble TDA8920.