Here is one another circuit in the series of audio power amplifier. We had already posted audio amplifier using transistor (3Watt and 20Watt) and using IC (7Watt). We used here IC TDA2020 for designing audio amplifier circuit. TDA2020 (IC1) can deliver a maximum of 20Watt into a 4Ω loads.
Like the TBA810, the TDA2020 also incorporated thermal shutdown, and output short-circuit protection. The input impedance of the circuit 20Watt audio amplifier using TDA2020 is determined by resistor R1 and sensitivity is determined by resistor R3 and R2. The input sensitivity of the circuit for 20Watt into 4Ω loudspeaker is 275mV.
A special feature of this IC is that it may be operated on a dual power supply. This eliminates the need for an output coupling capacitor an expensive and bulky component. Power output also is increased as there is no power loss due to effective series resistance and capacitive reactance of the output coupling capacitor. Besides, the low frequency response is improved, and savings are made in the power supply as a lower-voltage filter capacitor may be employed. However, when a dual supply is used, care should be taken to ensure that the supply rails always switch on and off together, even under fault conditions.
PARTS LIST OF 20W AUDIO AMPLIFIER USING TDA2020
Resistor (all ¼-watt, ± 5% Carbon)
R1 = 47 KΩ
R2 = 47 Ω
R3 = 100 KΩ
R4 = 1 Ω
|C1 = 10 µF/25VC2 = 5 µF/25VC3, C6 = 100 µF/25V|
C4, C5, C7 = 0.1 µF
|IC1 = TDA2020D1, D2 = 1N4002|
LS1 = 4Ω, loudspeaker