SG3524 Regulating Pulse Width Modulator

Description

SG3524 Pulse width modulation controller IC

Control-Integrated circuit for SMPS SG3524: Pulse frequency modulation and pulse width modulation are two types of techniques used in control integrated circuits for switch-mode power supplies. In Pulse frequency modulation technique on time of pulse remains constant but the frequency increases with the increase in load. But the Pulse frequency modulation technique causes some issues in switch-mode power supplies. On the other hand in Pulse width modulation technique frequency remains constant but the width of pulse changes with the change in load. The width of the pulse or on time increase with the increase in load. Pulse width modulation also resolves the issues which occur in Pulse frequency modulation. Therefore, Pulse width modulation is a preferred technique for control circuits of switch-mode power supplies.

Types of PWM controllers

There are many PWM ( Pulse width modulation ) controller integrated circuits available in the market just like SG3524. These PWM controllers ICs you can use very easily in your SMPS projects by connecting some external circuitry with them according to the selection of frequency. I will discuss these things in detail later in this article. There are two types of PWM controller integrated circuits:

• Voltage control PWM controller
• current control PWM controller

The voltage control method used a feedback voltage by comparing it with a reference value to set a duty cycle of PWM. In return to control the output voltage of SMPS. While the current control method uses Output current from output inductor to compare it with the reference value and to set the duty cycle of PWM. I have used a voltage mode PWM controller in pure sine wave inverter. Sg3524 is used in Dc to DC converter part to control the output voltage and for switching of MOSFETS connected to push-pull converter chopper.

Introduction to SG3524

• It is a pulse width modulation controller IC which has 16 pins.
• It provides two pulse width modulator signal which is a complement of each other.
• It is used to generate a PWM signal for power electronics projects and also for switch-mode power supplies.
• It offers feedback circuitry to control the output voltage by comparing the feedback signal with a reference voltage.
• It has a protection circuitry that shutdown the PWM signal based on the feedback current limit.

Features of SG3524

• It can operate with a supply voltage of between 8 and 35 volts. It may damage above 40 volts.
• It also has an external oscillator synchronization pin.
• It has a pulse to pulse shutdown capability.
• It can operate with a frequency range of  100 to 400KHz.
• It also provides a feature of versatile dead-time control between switching signals to turn on or off devices like MOSFETs, IGBTS and power transistors.
•  The maximum power dissipation is about 1000mW.
• Other similar integrated circuits are SG2524, UC3524
• For further features and specifications check datasheet.