What are you building? (e.g., buck, boost, push-pull, half-bridge)
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+-----------+ VCC (12V - 40V) | TL494 IC | | +-----------+ | Ground -------------| 7 (GND) | +------------------+ | | | +5V Ref Output -----| 14 (REF) +---------+ | | | | | Mode Select --------| 13 (CTRL) |<--------+ (Push-Pull) | | | | Oscillator Resistor-| 6 (RT) |<--- [RT Resistor] | Oscillator Cap -----| 5 (CT) |<--- [CT Capacitor] | | | | Dead-Time Control --| 4 (DTC) |<--- [10k Trim Pot] | | | | Feedback Loop ------| 3 (FEEDBK) | | | | | Driver Outputs: | | | Collector 1 --------| 8 (C1) +----------------------+ | Emitter 1 ----------| 9 (E1) |---> [Gate Driver 1]--|--+--> [MOSFET Q1] | | | Collector 2 --------| 11 (C2) +----------------------+ | Emitter 2 ----------| 10 (E2) |---> [Gate Driver 2]-----++--> [MOSFET Q2] | | | Error Amp 1 Input --| 1 (1IN+) |<--- [Voltage Sense] | Error Amp 2 Input --| 16 (2IN+) |<--- [Current Sense] | +------------+ | | | +--------------------------------+ Essential External Sub-Circuits Explained A. Oscillator Components ( RTcap R sub cap T CTcap C sub cap T
The TL494 is arguably one of the most successful and iconic integrated circuits (ICs) in the history of power electronics. Introduced by Texas Instruments in the late 1970s, this fixed-frequency, pulse-width modulation (PWM) control IC has stood the test of time. From inexpensive computer power supplies (PSUs) in the 1990s to modern inverter circuits, battery chargers, and DC-DC converters, the TL494 remains a favorite among hobbyists and professional engineers. tl494 circuit diagram
In this guide, we’ll break down the TL494 circuit diagram, how it works, and how you can use it in your own DIY power projects. What is the TL494?
To prevent heavy inrush current during startup, an external capacitor can be wired between Pin 14 ( VREFcap V sub cap R cap E cap F end-sub
The TL494 is a monolithic integrated circuit designed by Texas Instruments. It is a PWM control circuit that can be used to control the output voltage of a switching power supply. The TL494 is a versatile IC that can be used in various applications, including: What are you building
Output mode control (Single-ended or Push-Pull). REF (Pin 14): 5V Internal Reference Output. 2IN+ (Pin 15): Non-inverting input of Error Amp 2. 2IN- (Pin 16): Inverting input of Error Amp 2.
) from Pin 5 to GND. This sets the internal oscillator to roughly 110 kHz, yielding a 55 kHz switching frequency per output channel.
Prevents "shoot-through" (where both output transistors are on at once, causing a short). Introduced by Texas Instruments in the late 1970s,
is a staple in the world of power electronics. Whether you're building a custom inverter or a high-efficiency bench power supply, this fixed-frequency Pulse Width Modulation (PWM)
) biases Pin 4 to ensure an approximate 5% dead time. This prevents both switching MOSFETs from turning on simultaneously. 3. Variable Buck Converter Circuit Diagram
Two uncommitted BJTs capable of sourcing or sinking up to 200mA each. 2. Standard TL494 Circuit Configurations
Example: 12V→5V, 3A, f_osc=50kHz, ΔI_L=1A L = (12‑5)×(5/12) / (1×50000) ≈ 58µH C_out = 1 / (8×50000×0.050V) ≈ 50µF (use low‑ESR, e.g., 220µF+ ceramic)