TDA7294 is a high-power and high-voltage DMOS high-fidelity power amplifier IC produced by ST (SGS-THOMSON). The package is a single-row dual-row 15-pin package. VS (power supply voltage) ±10---±40V; I. (Output power peak value) 10A; p. (RMS continuous output power) 70W when VS=±35V 8Ω; 70W when VS=±27V 4Ω. Distortion <0.006%.
The design of this chip focuses on tone, and has the advantages of bipolar signal processing circuit and power MOS. It has the characteristics of high pressure resistance, low noise, low distortion, and very affinity for replaying sound; and has a silent standby function, short-circuit current and overheat protection functions to make its performance more perfect.
Note: This board is DC powered and cannot be directly connected to the transformer output. A power board must be added.
Product materials:
PCB board 1.6MM glass fiber board, coupling is original brand new WIMA, chip is original brand new, other parts are imported brand new parts such as chemical industry, ELNA, ruby, Siemens.
Installation and use note:
1. The working power supply is DC voltage, which cannot be directly connected to the transformer. It must pass through the power supply board.
2. Insulating particles and insulating sheets must be installed between the chip and the heat sink.
3. It is recommended to use dual 15-28V transformers with a power of no less than 100W The speaker impedance is 8Ω. It is recommended that the transformer output voltage is dual 24V. When the speaker impedance is 4Ω, the transformer voltage output voltage is recommended to be below 21V, and pay attention to increasing the heat dissipation area.
4. During power-on test, the signal input terminal on the board should be connected to a load, and it should not be suspended, otherwise there will be inductive noise, and the signal line should be shielded as much as possible.
5. If the board is installed in the chassis, the shell of the chassis must be connected to the input ground wire on the board. If it is added to the front stage, the input ground of the rear stage does not need to be connected to the chassis. Just connect the input ground of the front stage to the chassis. That is, if both are connected, it will cause a ground loop and generate noise.
There are several situations in which TDA7294 is prone to fireworks (IC burning) because the output end is a field effect tube:
1. The positive and negative voltages of the power supply are asymmetrical. If the voltage rectified by the transformer is +35V and -30V, fireworks
2. When the capacitor is not discharged, power on the IC and fireworks (Pay special attention to this when DIY soldering)
3. Touch the input terminal by hand when powering on and work, fireworks
4. The chip and the heat sink must conduct good heat conduction, and the heat sink must be well insulated if it is grounded, because the IC shell is connected to negative pressure, otherwise fireworks
5. Wrong component welding (such as reversed capacitor polarity welding), fireworks may occur, wrong output short circuit, fireworks