2W audio power amplifier LM380 circuit


Posted on Nov 10, 2015

Shown for the 2W audio power amplifier. The circuit uses a 14-pin package LM380 as amplifier element, the input signal by the volume control potentiometer


2W audio power amplifier LM380 circuit
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Rp (20k ) and 22 F coupling capacitance to the inverting input of the op amp (pin 6) LM380, the inverting input terminal ( pin 2) to ground, pin 1 external 10 F filter capacitor to filter out high frequency ripple interference, the circuit uses 16V single power supply and power supply terminal (pin 14) to an external decoupling capacitor between ground 470 F , the output terminal (pin 8) has two parallel branches between the ground: a route 2.7 resistor in series with the capacitor 0.1 F, for improving the stability of the circuit, filter out the high frequency portion, to prevent high self-excited oscillation frequency; another branch of the 470 F coupling capacitor Co and load ZL (8 speaker) composition, Co and ZL determines the lower cutoff frequency of the circuit fL. From the figure of the parameters which can be derived lower cut-off frequency is:fL = 1 / (2 ZLCo) = 1 / (2 8 470 10-6) = 42Hz. Clearly, we want to reduce lower cut-off frequency, may be appropriate to increase the value of Co. LM380 voltage magnification at a fixed value 50, the value is determined by its internal feedback circuit, no external components, the maximum output power up to 2.5W, but the larger output power, its power supply voltage ripple interference will increase Great, so the output power is generally used as 2W. The device supply voltage scope is wide: l0 ~ 22V, input impedance is higher: about 150k .




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