ClassDamplifier125Wsubwoofer----- 125W class d power amplifier

125W D-class ultra-low power amplifier, 125W Class D Power Amplifier Keywords: 125W D-class ultra-low power amplifier The 125W D-ultra-low-power amplifier circuit for the new LM4651 and LM4652 designed with US National Semiconductors is shown in the figure. The amplifier is 125W at the total harmonic distortion THD = 1%, the load impedance RL = 4Ω, the input signal Vin (RMS) is 3V, and the input signal bandwidth is 10 to 150 Hz, and the ambient temperature is 50 ° C, The power supply voltage is ± 20V. LM4651 with 28-foot DIP package is a PWM control / driver IC, a built-in oscillator, a PWM comparator, an error amplifier, a feedback amplifier, a level shift, a high-end drive, a low-end drive, and an undervoltage, overheating, short circuit, and over-conditioning circuit. . The LM4652 is a half-bridge power MOSFET IC, 4 MOSFET breakdown voltage V (Br) DSS = 50V, DSS = 50V, D 4 MOSFET's breakdown voltage V (Br) DSS = 50V, The drain current ID = 10A, open state resistor RDS (ON) = 200mΩ (typ), the open voltage VGS (TH) = 0.85V (typ). The oscillator frequency FOSC = 1 × 109 / (4000 + ROSC) in LM4651, where ROSC = R6 = 3.9kΩ, so FOSC = 125kHz. The input audio signal is input to the gain of 75V / V (i.e., 175dB) error amplifier. The half-bridge switch output on the IC27 pin and {15} foot is fed back to the {14} foot of IC1 through the RC filter filter. The {19} foot is output from 9 foot to the 9 pin, supplied to the error amplifier A single-ended feedback signal. The audio input signal compares the triangular waves generated by the oscillator, generating a square wave pulse that is proportional to the input audio signal electrode in the PWM comparator output to drive the power MOSFET in IC2. The switch output of the IC27 feet and {15} foot is powered by L1, C16, and L2, C17 low-pass filtering, and drive the speaker work. The resistor R4 on the IC1 {18} feet is used as a short-circuit current limit. When R4 = 100kΩ, the short-circuit current level is not less than 10A; the resistor R5 on the {17} foot is used as a set dead time; the capacitance C9 on the {24} foot is used to set the start-up delay time (1 second) When the {13} foot (Stoby) is placed, the standby function, stop the pulse width modulation, turn off the power switch in the LM4652, consumes very low current. As long as the junction temperature of IC2 reaches 150 ° C, the output of its 4 pin is fed back to the {12} foot of IC1, and the heat shutdown function can be performed.

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