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42 Threads found on edaboard.com: tl431 Feedback
Hello, I wish to make out a feedback loop for a CCM current mode full bridge 250W. It has tl431 /opto feedback but not with the fast lane. Basically the tl431 has been set up like a type 3 opamp. then thers the opto with secondary side led resistor and a pullup resistor on the primary side, in the standard way (...)
hii, what would be the circuit and design parameters i need to consider if i have to design a feedback circuit using tl431 for a non isolated smps. Even though i am using a transformer. But the secondary and primary ground are common. 2. In a multiple output flyback smps, reflected voltage is secondary voltage multiplied by turns ratio.
I have searched for this a lot (on this forum and google). Can someone verify/explain how this circuit works? Here is my understanding: tl431 has a ~2.5V reference. The resistor divider of R1/Rlower creates a divided down output voltage. The difference between the output and 2.5V reference is the "error si
hello, Does adding a resistor in parallel with an SMPS feedback opto diode reduce the gain in the feedback loop? i mean like R33 in the following : ...because if we think about it, when the tl431 trys to pull current through the opto, it ends up pulling it through the resistor not as much
Do you agree with my reasoning? No. tl431 can be used with all kinds of frequency compensations you want to. A first prerequisite is, that you have an idea of the intended loop gain characteristic.
Hello, I do isolated , offline flyback. tl431/Opto-coupler feedback. The problem is, the 1K resistor that's across the opto-diode to provide the tl431 bias current, places a voltage across the opto-diode of 1 Volt.... ...this in turn makes it conduct current, which is a big big problem on maximum load, because if 180uA is drawn (...)
There are tons of applications circuits with isolated voltage feedback. Most use a tl431 as voltage reference on the secondary.
Hi I am doing offline flyback with Vout = 36V and 22W. The following feedback scheme, using tl431 biased by a current source, appears to work fine on the simulator, and solves the problem of running too much current through a bias resistor to the tl431 during times of light load...... CIRCUIT DIAGRAM:-
Hello, I am doing an offline flyback with vout = 36V at 22W. (the PWM controller is to be NCP1217) This is how i initially intended to do the feedback circuit........... tl431 feedback CIRCUIT with bias resistor ...The tl431 is only rated up to 36V, so i need the 20V zener as in the above di
Related to the tl431 output, the reference pin is an inverting input.
So I assume you didn't try it yet. If you have a working system with the tl431, it should be not too difficult to test a LT1009. If you assume there is virtual no current in the "ref" input, and the cathode-current versus cathode voltage (in the case the cathode is connected directly to the reference) behaves the same, you should be able to swap
C9, R6 and R1 are providing a loop gain compensation. They are necessary for stable operation. R2 causes a bias current. It may improve the large signal behaviour according to the TOP204 properties. Analysis of tl431 circuits has been discussed in previous edaboard threads, if I remember right. The part I don't understand is - why is the
Hi, The different types of feedback are: primary zener, secondary zener, simple resistor, zener-opto, tl431-opto. In the PIExpert software, on the left hand side, check for a part called feedback components. Double click that, and then you can see the different types of feedback circuits, the different components and (...)
Hi, you should combine it with a constant current source (tl431) & is as all other coupler to use... K. Added after 6 minutes: Some imrpession is possible from Fig.26... Read pls ST`s Appl Note: AN1059, & the sinilar topics by
Hi I konw there is some type of isolation feedback for smps . 1- with tl431 and one optocoupler 2- with auxiliary winding 3- current feedback I design one smps with this output 2500 v-DC and 20 mA can you suggest me to best type of feedback with some descriptions, please?? by regards,
In other words, as explained on page 288 & 289 of Basso?s book, this transfer function assumes that R(LED) is in the so-called ?fast-lane? and R(upper) is in the so-called ?slow-lane?. No. I don't have the book, but this assumption is neither according to the transfer function nor the text written at the schematic. As said in the
the best one will have a thorough undertaking of feedback and give transfer functions for all well as opto/tl431 feedback transfer functions. If it does not contain this....and you don't know how to derive transfer functions......then you and i will be on a wing and a prayer with our SMPS's Anyway, for simple level......i find
R11 should be connected directly to the +200V ouput. Then you calculate your R8 and R9 so as to get 20V at the output: Id=2.5V/R8. Id*(R8+R9)=200V Set Id to about 1mA or so and then R8=2K49. R9≈200K R11 should be chosen so as to limit the optocoupler current to safe limits. So let's ay you need a max of 10mA. then R11=200/10=20K I w
Generally you look at the tl431 just like an opamp and calculate the pole and zero that way. Can you please post your schematic? It's easier for me to explain then.
R813, R821, C819, C820, C822 FORMS A feedback LOOP STABILIZATION NETWORK FOR IC N804 (tl431 - PROGRAMMABLE REFERANCE), WHICH IS USED AS A VOLTAGE ERROR AMPLIFIER. THIS CIRCUIT SENSES OUTPUT VOLTAGE OF A CONVERTER / POWER SUPPLY & GIVES A feedback TO THE PWM CONTROLLER VIA OPTO COUPLER, DUE TO THE LC COMPONENTS IN THE PATH THE OUTPUT SIGNAL (...)