Monday, September 1, 2014

CLASS D AMPLIFIER BASED ON SG3524 PWM IC #11

SG3524 is a PWM controller IC. This IC is normally used in power management , in buck or boost converters. Since class D audio amplifier is can be understood with the analogy of SMPS power supply, we can use the SG3524 as the PWM generator for the class D audio amplifier. The voltage level of the audio input to the circuit determines the instantaneous duty cycle of the output waveform whose frequency can be determined by the use of timing resistor and capacitor RT and CT. Then the low pass filter at out desired frequency cut off the high switching frequency typically 400 KHz .
Here's the link for its datasheet from Texas Instruments (http://www.ti.com.cn/cn/lit/ds/symlink/sg3524.pdf).

Mosfet can be driven by using the MOSFET driver using the dedicated IC driver like International Rectifier's IR2101 with both high side and low side drivers.
Here's the link on basic of class D amplifier(http://shortedwire.blogspot.com/2014/08/introduction-to-class-d-amplifier-4.html).
The dead generator is used in the circuit in order to avoid the turning on of the mosfet on  high side and low side at the same time of the same side of the bridge.
Sorry for the low q schematic.

Here some terms explained in the class d amplifier
http://shortedwire.blogspot.com/2015/07/terms-explained-in-class-d-amplifiers.html

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