Diagram Patched — Tl494 Circuit

is a classic fixed-frequency Pulse Width Modulation (PWM) control integrated circuit (IC) that has served as the backbone for switch-mode power supplies (SMPS) for decades. Its enduring popularity stems from its comprehensive architecture, which integrates all the essential functions for PWM control—oscillator, error amplifiers, dead-time control, and output steering—into a single 16-pin package. The Core Architecture

Look for resistors from C1 and C2 to the gates of MOSFETs. Usually, you need a "totem pole" driver (like a pair of BC547/BC557) because the TL494's internal transistors cannot drive large MOSFET gates quickly.

The TL494 is a 16-pin IC designed for versatility. Unlike simpler PWM chips, it contains dual error amplifiers and flexible output stages that can drive anything from small BJTs to large MOSFETs in push-pull or single-ended modes. Key Pin Definitions Pin 1 & 2 (1-IN+, 1-IN-): tl494 circuit diagram

These act as the "brain," constantly comparing output levels to a reference to ensure stable voltage or current. Dead-Time Control (DTC): is a classic fixed-frequency Pulse Width Modulation (PWM)

[ f_osc = \frac1R_T \cdot C_T ]

The TL494 has the following key components: Look for resistors from C1 and C2 to the gates of MOSFETs

In a functional analysis, the diagram shows that the capacitor CT is charged by the current through RT and discharged internally. This creates a sawtooth waveform on the timing capacitor. This waveform is the timing clock for the PWM. It feeds into the comparator section, establishing the "ramp" against which the control voltage is compared. The visual simplicity of two pins on the diagram belies the complex timing generation that dictates the switching speed of the entire power supply.

Sets the operating frequency (up to 300kHz) using just one external resistor and capacitor. Dual Error Amplifiers: