TL494 Modified Sine Wave Power Inverter 12V-220V DC-AC
TL494 Modified Sine Wave Power Inverter Circuit
12V to 320V DC to DC Power Converter Circuit:
TL494 dc dc power converter circuit 12v to 320v DC
This section basically converts low voltage DC at about 12 volts to high voltage DC of about 320V. Output regulation is provided by means of a feedback network composed of a resistor divider network, a 2.5V voltage reference IC (TL431), and an optocoupler IC which provides feedback to the switching TL494 PWM IC and also offers galvanic isolations between the high voltage and low voltage circuits for additional safety.
320V DC to 240V AC RMS Inverter Circuit:
TL494 low frequency modified sine wave Full H Bridge Driver Inverter Circuit (DC to AC)
Here, the HVDC generated in the DC DC converter section is converted to a modified Sine Wave Alternating Current of about 240V rms. This feat is accomplished by a Full H-Bridge circuit made up of four power Mosfets, a mosfet Gate Drive Transformer (GDT), and a 50Hz low frequency oscillator controller circuit built around another TL494 IC. The four bipolar junction transistors act as current amplifiers to reduce the load current supplied by the TL494 IC.
Watch the YouTube Video Tutorial:
TL494 IC Basics:
The TL494 is a popular Pulse Width Modulation (PWM) controller integrated circuit (IC) commonly utilized in Switched Mode Power Supplies (SMPS) and power inverters. Developed by Texas Instruments, the TL494 is designed to control the duty cycle of the output waveform, enabling efficient power regulation in electronic systems.
TL494 IC Features and ApplicationsKey features of the TL494 include:
PWM Control: The TL494 generates a PWM signal that controls the on and off times of a power switch in the SMPS or inverter circuit. This allows for precise regulation of the output voltage.
Voltage Reference: The IC incorporates a voltage reference source that facilitates accurate comparison with the feedback voltage from the output. This helps maintain stable output voltage regulation.
Error Amplifier: The TL494 includes an error amplifier that compares the feedback voltage with a reference voltage and produces an error signal. This signal is then used to adjust the duty cycle of the PWM signal, ensuring the output voltage remains within the desired range.
Soft-Start Function: To prevent sudden high current surges during startup, the TL494 often includes a soft-start function, gradually ramping up the output voltage.
Dead-Time Control: The IC provides dead-time control to avoid shoot-through currents in the power switches, enhancing the overall efficiency and reliability of the power supply.
Oscillator Section: The TL494 has an oscillator section that generates the clock signal for the PWM operation. This clock frequency can be externally adjusted to suit the application requirements.
Shutdown and Error Amplifier Disable: The IC typically includes a shutdown pin to disable the device when needed, conserving power. It may also have a feature to disable the error amplifier.
Wide Application Range: The TL494 is versatile and finds application in various power electronics systems, including power inverters, uninterruptible power supplies (UPS), battery chargers, and other SMPS designs.
Designers appreciate the TL494 for its flexibility, reliability, and ease of use in implementing PWM control in power electronics applications. Its widespread use and availability make it a standard choice for engineers working on power supply and inverter designs.
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| TL494 PWM IC features and applications |
TL494 IC Pinout and Frequency Formula Calculation
TL494 PWM IC pinout and basic internal block diagram
TL494 ic pinout and pin functions
TL494 ic frequency formala calculations for push pull and single ended applications
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| TL494 representative internal block diagram |
How the Inverter Works:
DC to DC Converter (12V DC to 320V DC)
stage 1 switching
stage 2 switching
Output Voltage Regulation and Feedback with Optocoupler (Optical Isolator)
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| Output Voltage regulation with tl431, optocoupler, and voltage divider resistor network |
HVDC to Modified Sine Wave AC Inverter (320V DC to 240V AC rms)
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| TL494 Full H Bridge Modified Sine Wave Inverter stage 1 demonstration |
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| TL494 Full H Bridge Modified Sine Wave Inverter stage 2 demonstration |
TL494 Current-Mode PWM Controller IC Explained: Pinout, Equivalent, Sample Circuits, Applications, Features
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The TL494 IC is a fixed frequency current-mode PWM controller IC with all the functions that are required in the construction of the pulse-width modulation (PWM) control circuit on a single chip.
TL3843 Pinout Configuration
Pin Number | Pin Name | Description |
1 | 1IN+ | Noninverting input to error amplifier 1 |
2 | 1IN- | Inverting input to error amplifier 1 |
3 | FEEDBACK | Input pin for feedback |
4 | DTC | Dead-time control comparator input |
5 | CT | Capacitor terminal used to set the oscillator frequency |
6 | RT | Resistor terminal used to set the oscillator frequency |
7 | GND | Ground Pin |
8 | C1 | The collector terminal of BJT output 1 |
9 | E1 | The emitter terminal of BJT output 1 |
10 | E2 | The emitter terminal of BJT output 2 |
11 | C2 | The collector terminal of BJT output 2 |
12 | VCC | Positive Supply |
13 | OUTPUT CTRL | Selects single-ended/parallel output or push-pull operation |
14 | REF | The 5-V reference regulator output |
15 | 2IN- | Inverting input to error amplifier 2 |
16 | 2IN+ | Noninverting input to error amplifier 2 |
TL494 Specifications & Features
- Supply Voltage: 7V to 40V
- Number of Outputs: 2 Output
- Switching Frequency: 300 kHz
- Duty Cycle - Max: 45 %
- Output Voltage: 40 V
- Output Current: 200 mA
- Fall Time: 40 ns
- Rise Time: 100 ns
- Available in 16-pin PDIP, TSSOP, SOIC and SOP Packages
Equivalent/Substitute for TL494: UC3843, TL3842
Alternatives PWM controller IC: UC2842, SG2524
Where to use the TL494 PWM Controller IC
The TL494 fixed frequency PWM Controller can be used for DC to DC conversion regardless of buck or boost topology. TL494 can be used to provide a constant current by varying the output voltage to the load. This IC feature an output control circuit, a flip flop, a dead time comparator, two different error amplifiers, a 5V reference voltage, an oscillator, and a PWM comparator.
So if you are looking for an IC to produce PWM signals for controlling a power switch based on the current flowing through the circuit, then this IC might be the right choice for you.
How to use TL494 IC
A test circuit from the TL494 datasheet is shown below.
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Non inverting pins are connected to the Ref pin while inverting pins are connected to the ground. Test inputs are given to DTC and FEEDBACK pins. External capacitor and resistor are connected to pin 5 & 6 to control the oscillator frequency. The error amplifier compares a sample of the 5-V output to the reference and adjusts the PWM to maintain a constant output current
Applications of TL494
- Desktop PCs
- Microwave Ovens
- Server PSUs
- Solar Micro-Inverters
- Washing Machines: Low-End and High-End
- E-Bikes
- Power: Telecom/Server AC/DC Supplies:
- Smoke Detectors
- Solar Power Inverters
2D-Model of TL494
Dimensions for TL3494 IC is given below. These dimensions are for the PDSO package. If you are using a different package IC, please refer to the TL494 datasheet.
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| TL494-Dimensions 2D PCB Footprint electrobuff.blogspot.com |
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make circuit pcb and share the project files
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