The schematic diagram of the Class D power amplifier is shown in the figure. The output terminal is connected to the primary of the load matching transformer, and the secondary of the transformer is connected to the load. When P4 is applied with 30V and 35V voltage, the tube works normally, and it works normally for 10 times. Once the voltage is increased to 40V, the tube will be burnt when working, and only one is burned. Two experiments were done, the first time Q1 was burned, the second I burned Q2 this time, and I hope the great god can help to see why the tube was burned?
Simona Posted on October 29, 2020
Model not marked
Sion Posted on October 29, 2020
Caused by a circuit error!
The upper ends of Q1 and Q2 are connected to the power supply, yes.
The lower ends of Q3 and Q4 are both grounded, yes.
The lower ends of Q1 and Q2 are also grounded! !
So, whichever you turn on, burn it! !
The upper ends of Q3 and Q4 are also connected to the ground! !
Therefore, the voltage difference between the upper and lower ends of them is always zero, and they can't burn and survive.
The output terminals OUT+ and OUT- are shorted to ground! !
What do you want? !
Mimi Posted on October 29, 2020
The H-bridge drive is turned on on the opposite side. You can see that the drive timing is abnormal. Have you considered the dead time of MOS?
