SG3525 PWM CARD
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The SG3525 is a highly versatile and widely used Pulse Width Modulation (PWM) controller integrated circuit (IC), and a "SG3525 PWM card" typically refers to a small circuit board or module built around this IC.
This module is designed to generate the precise PWM signals needed for controlling power electronic circuits.
Key Features of the SG3525 PWM Controller IC/Module
The SG3525 is popular due to its comprehensive features, which are especially useful in Switch-Mode Power Supplies (SMPS), DC-DC converters, and inverters.
PWM Generation: It generates a pair of complementary (out-of-phase) PWM signals, ideal for driving power switches like MOSFETs or IGBTs in half-bridge, full-bridge, or push-pull topologies.
Adjustable Frequency and Duty Cycle: The PWM frequency (up to 400kHz) and the output pulse width (duty cycle) can be easily adjusted using external resistors and capacitors (connected to the R_T, C_T, and R_D pins).
Adjustable Dead Time: It includes a dedicated pin for adjusting the dead time (a small delay between the turn-off of one output and the turn-on of the complementary output), which is crucial for preventing "shoot-through" short circuits in the power stage.
Soft-Start Functionality: A capacitor connected to the Soft-Start pin allows the output voltage to ramp up gradually, preventing excessive inrush current during startup.
Protection Features: It includes an Undervoltage Lockout (UVLO) to prevent operation with an unstable supply voltage and a Shutdown (SD) pin for immediate pulse-by-pulse or sustained shutdown.
Internal Voltage Reference: The IC has a trimmed 5.1V reference voltage (1% accuracy) used internally for the error amplifier, which is also often available on a pin for external use.
SG3525 PWM Card Application (Inverters)
The most common application where you hear of an "SG3525 PWM card" is in the design of power inverters (DC to AC conversion).
Function in Inverters: The module acts as the "brain," generating the high-frequency PWM pulses that switch the inverter's power MOSFETs.
Voltage Regulation: In a closed-loop inverter design, the SG3525's built-in error amplifier compares a feedback voltage (a sample of the output AC voltage) with its internal reference. It then automatically adjusts the PWM duty cycle to maintain a stable, regulated output voltage despite changes in input DC voltage or load.