Flyback converter design using tl494 ee times india. I see you are using a mkptype capacitor in the oscillation section of the. Fueled by this thought i made a tl494 based oscillator which has separate pulse width and frequency control. In this ac power supply, a pushpull oscillator drives a tv flyback transformer from an old color tv a flyback without embedded tripler. This power supply has atx design and 200w performance, tl494, switching regulator, switching mode power supply circuit smps 20w, 5v at 4a, stepdown regulator lm2577, a 20w, 5v at 4a, stepdown regulator can be developed using the lm2577 simple switcher ic in a forward converter topology. Component selection and magnetics design is also shown. Essentially a pwm driver for the flyback transformers found in old crts. A zvs driver is a very simple circuit that can oscillate a large amount of power with about 90% efficiency.
Its an inverting driver fabricated in cmos for lower power and more efficient operation versus bipolar drivers. A half bridge flyback driver is a neat project for any beginner hv enthusiast, which reflects much of the way a commercial high voltage power supply might be made. By tuning it properly you are able to get insane power outputs. It will make a several thousanddegree continuous 2 cm plasma arc. The zvs flyback driver either using bjts or mosfets have been used in high voltage devices such as tesla coils, marx generators, ion experiments, and ccfls. Sep 25, 2019 the oscillator circuit uses a transistor q1 2sc828 is base works with three capacitors c1, c2, c3 and three resistor r1, r2, vr1, to produce a sine wave frequency the current amplifier and detect circuits has transistor q2 c828 is used to increase the signal to works with four resistor r3, r4, r5, r6, and r7 is used to limit current to the amp meter. I used a 9v battery to power the ne555 and a 24v 6a power supply to power the flyback. Safety is extremely important a flyback is not a toy. The tl494 pwm controller contains two error amplifiers, an onchip adjustable oscillator, a deadtime control dtc comparator, a pulsesteering control. Tl494 flyback driver, walkthrough of design and construction.
Coming to the royer oscillator circuit design, the input to the circuit is a 12v dc voltage source and the two transistors are named as q1 and q2. I didnt have the gate driver ics so i experimentally. This should make a driver that is able to run flyback transformers found in crt. Input power is 1530v dc, as the oscillator circuit is fed from an independent lm7812 linear supply. New things is a full bridge of irfp460 mosfets, audio modulation, shielded drivers and a new casing. I tried using a fast diode with a reverse recovery time of 100ns in between the source and drain of the mosfet, but that didnt do anything.
A very simple road to your basic high voltage generator is the transistor driven flyback transformer. Easiest way to make a hv supply from an old tv or pc monitor best flyback driver duration. One simple way to reduce the load on the mosfet is to add a diode and resistor in parallel between the gate driver and the mosfet gate to speed turnoff. Basically we use a 555 timer as an oscillator to generate a square wave between 10100khz. The switching circuit consists of a pair of irfp250260 mosfets and a pair of zener diodes that step up the 12 v d. The ltc3783 is a current mode led driver and boost, flyback and sepic controller that drives both an nchannel power mosfet and an nchannel load pwm switch. I set myself the task of making a pushpull high voltage flyback driver, i think it works quite well considering i wasnt using a very good flyback, but this could be a youtube first as i dont. To the right exists a simplified version of the oscillator, so take a good look. Well i said i wanted to build a pushpull oscillator, hence all the talk about tl494. The tl494 ic uses a 5% dead time to insure proper switching and at. Build a simplified a mathematical model of the used leds and the simulation in. Thanks to its high performance drivers and versatility, it can be used in various topologies such as dcm or ccm flyback, quasi resonant flyback, forward and. The mazzilli zero voltage switching zvs driver consists of two parts.
Slva001edecember 2003revised september 2011 designing switching voltage regulators with the tl494 5 submit documentation. Ncp4306 secondary side synchronous rectification driver. Tl494cn datasheet ti tl494, pulsewidthmodulation pwm. Tl494 pwm emi flyback converter overvoltage protections the tl494 is one of the earliest pulsewidthmodulation pwm controllers used in switched mode power supplies. Jan 07, 20 ct must be within the range 1nf code 102 to 0. The tl494 ic is designed for maintaining all the functions needed in a switching mode power supply using pulse width modulation pwm. The tl494 is one of the earliest pulsewidthmodulation pwm controllers used in switched mode power supplies. Designing switching voltage regulators with the tl494 rev. Oct 19, 2017 the tl494 incorporates all the functions required in the construction of a pulsewidthmodulation pwm control circuit on a single chip. The main advantages of this driver are simplicity of the circuit itself, very high efficiency and easily obtainable parts. Capacitor terminal used to set the oscillator frequency. It contains two error amplifiers, an onchip adjustable oscillator, a deadtime controldtc comparator, a pulsesteering control flip. The circuit first of all uses the very well known tl494 chip witch is a pulse. I wanted something powerful and very reliable i hate replacing mosfets and this is what i came up with.
If you only need 200 vac at 400 hz, definitely dont use a flyback. There are many flyback drivers schematics out there, but most of them will not last. Mcp1661 isolated flyback converter reference design user guide. The first and simplest driver designs generally consisted of a single silicon switch driving the transformer in flyback mode, which turns out as quite. The variable frequency is to allow the circuit to be tuned to the resonant frequency of the flyback transformer in use. Tl494 pulse widthmodulation control circuits datasheet rev. You can use 2x100w rms stereo or 200w rms mono, which can be controlled by bridge connection as well as bass control with cross over circuit with adjustable tl072p op amp at the main entrance floor. Abstract the selfoscillating flyback converter is a popular circuit for. The oscillator frequency must be within the range 100hz to 400khz. Pwm control circuit tl494 the tl494 incorporates all the functions required in the construction of a pulsewidthmodulation pwm control circuit on a single chip. Tl494 flyback driver running a halfbridge section connected to a flyback transformer.
Jun 14, 20 this should make a driver that is able to run flyback transformers found in crt tv sets and computer monitors. Isolated multiple output flyback converter design using tl494 srivatsaraghunath abstract the tl494 is one of the earliest pulsewidthmodulation pwm controllers used in switched mode power supplies. Tl494 flyback driver oscillator section high voltage forum. Most of the people in the 4hv community use the mazilli driver to make flyback transformers also known as line output transformers lopt from tvs and computer monitors. Firstly, i wanted more power, which apart from producing good looking arcs may make. Nov 19, 2015 bogin jrs ne555 quasiresonant flyback driver.
It is possible to generate even higher voltages from a flyback with a even more powerful driver but this may cause secondary coil insulation failure, rendering the flyback dead. Project description ignition coil drivers that utilize an oscillator chip like ne555 and a single switching device are a very common beginner hv project. The tl494 ic uses a 5% dead time to insure proper switching and at frequencies over 150 khz this minimum dead time is higher. Before current mode control was successfully implemented, the tl494 pwm mode ensured low emi and noise operation due to its trailing edge modulation technique. Design of a tl431based controller for a flyback converter. For me, it can supply about 15kv at a decent current with 24v 10a input. Our favorite circuit is the following dctoac inverter click diagram to enlarge. This driver is capable of pumping upto a kw of power, so impressive arcs can be made.
I just started playing around with some tl494 s i bought a while back for a flyback driver circuit. Box 12173, 5101 davis drive research triangle park, n. The zvs flyback driver, made popular by vladimiro mazzilli, is one of the most efficient and powerful flyback drivers used by high voltage hobbyists from all over the world. Tl494 circuits tl494 projects tl494 integrated two amplifiers, adjustable oscillator, dead time control dtc comparator, pulse steering control flipflop, a 5v precision regulator and output control circuits tl494 device can work as pushpull or single output. The ncp4306 is high performance driver tailored to control a synchronous rectification mosfet in switch mode power supplies. The circuitry from the tl494 to the gdt creates alternating pulses for the irfp450s at any desired frequency and duty cycle.
Introduction a flyback driver is a common amateur high voltage generator. Switching mode power supply circuits, smps, dcdc converter, psu. Complete pwm powercontrol circuitry uncommitted outputs for 200ma sink or source current output control selects singleended or pushpull operation internal circuitry prohibits double pulse at. High power full bridge flyback driver circuit under. At maximum settings the output of the flyback will be very high power, and is. To allow higher voltage inputs and bigger power outputs, get a separate 1216v dc supply a few watt transformer, e. Designed primarily for powersupply control, this device offers the flexibility to tailor the powersupply control circuitry to a specific application. The schematic has been updated to include basic transistor protection in the form of a capacitor and diode. The power transistors used ir2110 mosfet driver instead of transistor to enhance the output of tl494 igbt instead of irfp054n can be used spark grows in cost as the size grows. Cdc electronic workshop tl494 pushpull flyback driver, plus singing arcs and i get shocked.
Pc power supply unit, psu, smps switching mode power supply theory. It is best to mount the driver and mains transformer inside an old pc power supply. One possible realization of a tl494 driving a gate drive transformer. What youre looking for is a much simpler inverter circuit basically an audio oscillator hooked up to a backwards power transformer. Ever since seeing videos of flyback transformer drivers from the likes of keystone science and ant, aka high1voltage1rules on youtube, ive wanted to get myself a flyback or line out transformer and create my very own driver circuit with the aim of producing purple arcscoronas and maybe a little o. Mcp1661 isolated flyback converter reference design user. The tl494 ic is a fixed frequency currentmode pwm controller ic with all the. A schematic of the tl494 internal oscillator is shown in figure 5. The step 9 page going further now includes a way to measure these illustrious voltage spikes with a regular volt meter. Looking at it all afterwards the heatsinks were very warm, and the oscillator was only giving 3. Hi again, im looking for a pwm flyback controller which does not have an internal oscillator in it. Basic introduction of flybacks and the driver circuit flybacks.
A fully featured tl494 based forward converter, designed for powering a tube oscilloscope hence the 6. Jan 28, 2012 easiest way to make a hv supply from an old tv or pc monitor best flyback driver duration. The tl494 device incorporates all the functions required in the construction of a pulsewidthmodulation pwm control circuit on a single chip. This is switched through a pair of buffer transistors into a large stw45nm60 mosfet, rated at 650v 45a. The output voltage can be set to any value between v ref and 36 v using two external resistors. Introduction this is a modified version of the first sstc i built, the kaizer sstc i. The second ic chip that is being used as a mosfet driver and as inventer in the circuit is a 6a high speed mosfet driver, the tc4429 by microchip. You can use any highvoltage ac power supply to drive the multiplier. It is the same topology with almost the same efficiency, and its actually a nice example what happens when a primitive circuit like this is used with slightly bigger input. The approximate oscillator frequency is determined. To ensure that i could keep mosfet deaths to a minimum i put some safety features in place. Steve wards tl494based seriesloaded resonant slr fullbridge flyback driver this design uses a tl494 pwm ic and two heavyduty ucc37322 9a mosfetigbt drivers to drive four monstrous igbts hgtg30n60ad or fgh50n6s2d via two custom gate drive transformers. It uses the same secondary, topload and driver board. Flybacks are designed to output tens of thousands of volts at tens of thousands of hertz.
Zvs gives a lot of power, but the voltage is not great. There is a flipflop before the driver stage, due to which your output signals will have frequencies half that of the oscillator frequency that is calculated using the above mentioned formula. Maybe it must resonate with the flyback primary for a tank circuit with same fres as the fullbridge output then good. Tl494cn ti tl494, pulsewidthmodulation pwm control circuit. Analysis and design of selfoscillating flyback converter brian t. Recently i was experimentally building the tl494 driving circuit according to this schematic. It consists cathoderay tube tv high voltage transformer driven by a high frequency inverter, in order to obtain hv output. This circuit uses a common flyback transformer you probably have more than one in your house right now to boost typical battery voltages up to the multikilovolt range. Here the usage of the centertapped transformer in the oscillator is to forward the voltage through a dielectric medium from the two transistors output which is q1 and q2. Slva001edecember 2003revised september 2011 designing switching voltage regulators with the tl494 5 submit documentation feedback. It incorporates all the functions required in the construction of. The deadtime control comparator has a fixed offset that provides approximately 5% dead time.
Tl494, ncv494 switchmode pulse width modulation control circuit. In the second version, this work, which is a big tesla bobbin, is a buss but it gets bigger spark. Tl494 pulsewidthmodulation control circuits slvs074d january 1983 revised may 2002 4 post office box 655303 dallas, texas 75265 electrical characteristics over recommended operating freeair temperature range, vcc 15 v, f 10 khz unless otherwise noted. The tl494 pwm controller contains two error amplifiers, an onchip adjustable oscillator, a deadtime control dtc comparator, a pulsesteering control flipflop, a. The problem is that the mosfet gets very hot in a few seconds. This then runs a simple gate driver stage and finally a halfbridge.
The tl494 pwm controller incorporates all the functions required in the construction of a pulse width modulation pwm control circuit on a single chip. The tl494 device contains two error amplifiers, an onchip adjustable oscillator, a deadtime control dtc comparator, a pulsesteering control flipflop, a 5v, 5%precision regulator, and outputcontrol circuits. The circuit first of all uses the very well known tl494 chip witch is a pulse width modulation control unit designed in a very sophisticated way. Offline flyback driver the walls the limit running power through multiple transformers just to power another transformer seems a bit absurd, so i though it was time for a direct mains powered flyback driver. The oscillator provides a positive sawtooth waveform to the deadtimeand pwm comparators for comparison to the various control signals. It contains two error amplifiers, an onchip adjustable oscillator. Using the sg3525 pwm controller explanation and example. The motivation is that i want to provide my own oscillator signal and dont want to be limited by the sync pin restrictions compared to the internal oscillator frequency, so i can be flexible with the frequency that i choose and maybe change in the future. Transistor driven high voltage flyback transformer page. Mar 30, 2014 i recommend this driver to someone who is sick of a single transistor driver, but cant get mosfets for a zvs.
The error amplifiers exhibit a commonmode voltage range from 0. Isolated multiple output flyback converter design using tl494. Self oscillating smps circuit flyback 600w 60v 120khz. Since the leakage inductance of the transformer provides the current limiting, and there is never dc component on the primary, arcs can be safely drawn from the transformer without. The tl494 incorporates all the functions required in the construction of a pulsewidthmodulation pwm control circuit on a single chip. This driver rectifies mains and produces a 320v dc source. Designing the tl494 section i wanted the driver to be able to have a variable frequency fromm 50khz to 150khz, so lets find out the values needed. Cdc electronic workshop tl494 pushpull flyback driver. The pcb design, which resembles the project rms 250w auto amplifier jbl filter smps ei35 sg3525 that was previously shared, is a fairly regular auto amplifier circuit. More than 50 kilovolts out of a single flyback at 20 volts input.
Another point to note is in drawing electrical arcs from the output. Mcp1661 isolated flyback converter reference design 2014 microchip technology inc. Although the chips are pretty flexible looking at the datasheet. Half bridge ignition coil driver markos science site. Tl494 pulsewidthmodulation control circuits slvs074d january 1983 revised may 2002 4 post office box 655303 dallas, texas 75265 electrical characteristics over recommended operating freeair temperature range, vcc 15 v. This circuit, also incorrectly known as the 2n3055 flyback driver, bears some resemblance to the battery invertercontinuity tester which is published here. It is probably the most powerful and efficient flyback transformer driver that was fairly recently invented by vladmiro mazilli. In my own version, i pointed out some of most important problems with this kind of approach. Mcp1661 device short overview flyback converter topology overview. Jovanovic delta products corporation power electronics laboratory p. Flyback transformers from a crt tv are typically driven at 15 khz and flyback transformers from computer monitors are typically driven between 30 to 150 khz. High power full bridge flyback driver circuit under switching power. It incorporates all the functions required in the construction of a pwm control circuit on a single chip.