Simple Power Amplifier Circuit using IC TDA4935

Power amplifiers are super important in audio systems because they provide the power needed to make loudspeakers work well.

One of the best ones is the TDA4935 which is a powerful dual audio power amplifier integrated circuit.

It is often used in bridge amplifier configurations to get really high output power.

The circuit shown here demonstrates a bridge amplifier design that uses the TDA4935 IC, which can effectively power an 8 ohm speaker with impressive output power and very little distortion.

Circuit Working:

Parts List:

The TDA4935 is a power amplifier that boosts audio signals it needs to have a suitable heat sink attached to it.

In this circuit diagram, supply voltage ranges from +8V to 30V DC.

It has a setup with input capacitors, feedback parts and output connections all designed to make audio amplification as efficient as possible.

The audio signal comes into the amplifier through specific input pin 7 and pin 2 using coupling capacitors called C1 and C2 each with a value of 1µF.

These capacitors are important because they block any direct current DC from the input signal allowing only the alternating current AC audio signal to be amplified.

To keep the amplifier stable and set the right gain feedback resistors R1 and R2 both at 1ohm work with capacitors C3 and C4 which are 220nF each.

This combination of parts is crucial for shaping the frequency response and reducing distortion.

After the audio signal is amplified it goes to the speaker with an 8 ohm impedance through a coupling capacitor C5 which is 100µF.

This capacitor is key because it stops any DC from reaching the speaker protecting it from damage.

Additionally, decoupling capacitors C6 and C7 and C8 are used to provide a steady power supply to the integrated circuit.

These capacitors help filter out noise or changes from the power source.

The TDA4935 works in a bridge mode meaning both output terminals of the speaker are powered by the IC in opposite phases.

This clever design doubles the voltage swing across the speaker which effectively quadruples the output power compared to a regular single ended setup.

Formulas with Calculations:

The below formulas with calculations can help to design the Simple Power Amplifier Circuit using IC TDA4935

Gain of the Amplifier (Av):

Av = Rf​ / Ri

where,

• Rf is the feedback resistor
• Ri is the input resistor.

In this circuit, the feedback network sets the gain automatically, as determined by the ICs internal configuration.

Output Power (Pout):

Pout = Vrms2​​ / Rload​

where,

• Vrms​ is the RMS output voltage
• Rload is the speaker resistance to 8 ohms.

Decoupling Capacitor Value:

Cdecouple​ = 1​ / 2πfmin​R

where,

• fmin​ is minimum frequency to be amplified
• R is the load resistance.

Coupling Capacitor Value:

Ccouple​ = 1 / ​2πfc​R

where,

• fc​ is the cut off frequency typically chosen to be below the audible range 20 Hz

How to Build:

To build a Simple Power Amplifier Circuit using IC TDA4935 follow the below mentioned steps:

• Gather all the components as mentioned in the above circuit diagram.
• Connect pin 1 of IC TDA4935 to one end of 8Ω speaker and connect capacitor C4 and resistor R2 in series and GND
• Connect pin 2 of IC TDA4935 to pin 7 through capacitor C2.
• Connect pin 3 of IC TDA4935 to GND through capacitor C7
• Connect pin 4 and pin 6 of IC TDA4935 to GND
• Connect pin 5 of IC TDA4935 to positive supply of +8V to 30V through capacitors C6 and C8 and GND as shown in circuit diagram above.
• Connect pin 7 of IC TDA4935 to audio input through capacitor C1 and GND.
• Connect pin 8 of IC TDA4935 to GND through capacitor C5.
• Connect pin 9 of IC TDA4935 to other end of 8Ω speaker and connect capacitor C3 and resistor R1 to GND in series.

Conclusion:

The TDA4935 power amplifier is a great choice for powering low impedance speakers with a lot of power.

Its easy design along with the strong performance of the TDA4935 chip makes it perfect for DIY audio projects and smaller sound systems.

If built correctly and with a good heatsink, it can provide clear and steady audio without any distortion.