OCL power amplifier composed of LM2876

LM2876 is a high-power monolithic power amplifier circuit recently launched by National Semiconductor . Its instant
peak output power can reach 75W for 80 load, and
the average continuous output power is 25W. This integrated circuit has
a wide power supply voltage range (±lov ~ ±30V)
and good linear output characteristics. Like other LM series
power amplifier circuits, the LIW,876 circuit is equipped with a noise
suppression circuit and an overload short-circuit protection circuit. The signal-to-noise ratio can
reach 95dBo.
    The LM2876 adopts a single-sided dual-in-line package. Its main electrical performance parameters are shown in Table 2-11. The functions of each pin
are: pin 1 is the positive power supply terminal (V+); pins 2, 5, and 611 are empty pins; pin 3 is the output terminal; pin 4 is the negative power supply terminal (V-);
pin 7 is the AC ground terminal, and the other pins are The DC potential is the midpoint level (oV when powered by dual power supplies, V/2: when powered by single power supply):
Pin 8 is the external terminal for silent switch (squelch control); Pin 9 is the inverting input terminal; Pin 10 It is the non-inverting input terminal.
    Figure 2-54 shows the OCL power amplifier circuit for LM 2876 dual power supply . In the circuit, resistors R6, R7 , capacitor island, and inductor Ll form a low-frequency bandpass network to improve the low-frequency characteristics of the power amplifier. Resistors R3, R2, R, capacitor islands, and C series and parallel networks form the RC negative feedback network of the power amplifier circuit. It not only determines the closed-loop gain of the entire power amplifier, but also improves the low-end frequency response of the circuit . The actual effect and needs can be seen during debugging. Appropriately adjust the value t of RC to achieve the best effect. The mute control terminal M can be connected to the negative power terminal (V-) through an external button switch to achieve mute control. C4 is a decoupling filter capacitor to filter the AC power supply .