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Questions tagged [tl431]

For questions about the three-terminal shunt regulator. Use in conjunction with the "voltage-regulator" or "voltage-reference" tags, as applicable.

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Replacing the BJT in the current limiting circuit with a MOSFET

I was looking for a current limiting circuit and found an implementation using TL431 and a bipolar transistor. However, I did not have a bipolar transistor at hand for the required current and ...
Typeof undefined's user avatar
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1 answer
47 views

CS1237 ADC - series resistor of voltage reference too big?

I've recently tried multiple times to get consistent readings of a loadcell with a CS1237 ADC-module like the following: https://www.androegg.de/shop/cs1237-24-bit-adc-ad-konverter-modul-tl431/ It ...
Seppde's user avatar
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1 answer
37 views

About "source/sink current on FB line" in IP2701 datasheet

There is a part I don't understand while reading the IP2701 dataset. [When fast charging client-side device connected, IP2701 auto-detect the type of charging standard and analysis the power ...
 8  minikhh's user avatar
6 votes
3 answers
483 views

Modified output voltage range of laptop power brick? (TL431)

So here I have a standard 19V noname laptop power brick rated at say 4A output. Inside is a typical SMPS regulated by a TL431 and an optocoupler. I added in a potentiometer to the reference resistors ...
parkside's user avatar
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1 vote
0 answers
80 views

Using TL431/ATL431 to make UV lockout circuit for gate driver IC

I am using UCC5350 (isolated gate driver) in 3 phase bridge circuit, sadly I decided later in the project to use isolated Bipolar dc/dc converter MGJ2D241509SC (+15/-9) for gate drive supply. 15 V ...
Eng Sam's user avatar
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0 answers
118 views

TL431 With LM317 BMS

I am trying to make a BMS circuit that I saw online using a TL431, but as I am new to electronics I am having some problems when using the TL431. When I wanted to check the reference pin of the TL431,...
Fuad Frehat's user avatar
2 votes
1 answer
831 views

Is it OK for a TL431 to be power cycled at high frequency?

For a project I have a switched capacitor supply that creates a +15V/-15V output from a single positive input. I also need a small (+-20mA) 5V supply (crude regulation is OK). So I thought I could ...
Unimportant's user avatar
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1 vote
0 answers
288 views

Modifying XL4015 CC/CV Buck Converter for Undervoltage Lockout

I am trying to convert a XL4015-based CC/CV buck converter module to CV with undervoltage lockout. At this point I am hoping someone can double check my schematic for glaring errors before I attempt ...
moonTV's user avatar
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0 answers
54 views

Low Battery Detection Circuit

I'm trying to light up an LED when my li-po battery level drops below 3 V. I have been using the scheme you can see in the picture. The only change I have made has been to adjust the values of the ...
Asier Mintegia's user avatar
4 votes
2 answers
354 views

compensation for flyback regulator with 431 and optocoupler

I am testing a flyback converter with secondary side regulation, by means of a 431 in conjunction with an optocoupler with nominal CTR of 50-100%. A snippet of the regulator part is below. I have used ...
tobalt's user avatar
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1 vote
4 answers
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Isolated DC voltage measurement via optocoupler

I am trying to make a circuit that measures 10-30V DC with isolation. The measurement is done by the circuit, not manual. The measured voltage level/information is sent via an optocoupler to the ADC ...
elec3's user avatar
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0 votes
5 answers
731 views

TL431 constant-current source voltage drop

Is it possible to somehow eliminate or reduce the TL431 constant-current source voltage drop? I have studied this application note from TI. In my opinion, it nicely presents the possibilities of using ...
OH1LLN's user avatar
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2 votes
2 answers
520 views

Precision voltage reference for ADC

I'm designing a precision voltage reference for an ADC. The aim is to sample a 230 Vrms AC signal using the STM32F411 built-in ADC. An opamp-based differential amplifier is used to convert a 325 V ...
Vivek Vijayan's user avatar
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67 views

How to use an MCU's digital pins and zeners/voltage-references to determine battery voltage?

I'm making a wireless temperature sensor node using a STM8L101F3 and 2xAAA batteries with low power considerations. The MCU lacks an ADC and to measure battery level I'm thinking about using a few ...
Tirdad Sadri Nejad's user avatar
1 vote
1 answer
106 views

LMV431 to generate negative voltage

can someone show me how to use LMV431 to generate -1.24 V from -5V? below is how I use it for positive. Thank you
Kurt Müller's user avatar
0 votes
1 answer
1k views

Designing A Circuit To Light An LED When Voltage Drops Below Threshold

I'm a beginner with designing circuits and I'm attempting this because I'm trying to design my first PCB. The basic idea is that I have a 12V battery as a power source and I want an LED to light up ...
redixhumayun's user avatar
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1 answer
108 views

How can I calculate the max. allowable load for my reference voltage?

I have a 2.5V reference voltage set up like so: I want to determine how many ohms in load this 2.5V can bear before the TL431 is unable to hold the voltage. I know that this IC requires 500uA to 1mA ...
Ozbekov's user avatar
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7 votes
6 answers
3k views

Power cutoff for car when power drops below 13V

I just bought a 2004 Explorer. I have a wireless phone charger and GPS plugged into the cigarette lighter port. The problem is this is always on even when the car is off so I'm forced to unplug ...
hdelien's user avatar
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1 answer
330 views

TL431 output wrong

The purpose of the circuit below is to get a V_cathode of 2.5V (Vref) when VDC is higher than 10.4V approximately. The problem is that when VDC>10.4V the voltage checked in V_cathode is 1.9V ...
robocotec's user avatar
2 votes
1 answer
474 views

TL431 on-mode voltage

The TL431 datasheet mentions that the VIKA is approximately 2 volts (when the input is more than Vref = 2.5 V), but based on my simulation, it shows me (1.07 V to 1.2 V). I need to know where I can ...
John Jin's user avatar
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2 votes
0 answers
1k views

Switched power supply output voltage modification

After days of research and experimentation, I was unsuccessful in modifying a power supply output voltage from 15.3V to 5V. My work was focused on the output section of this switched mode power supply,...
alonjr's user avatar
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1 vote
0 answers
569 views

Undervoltage detection using TL431 with high rail voltage

I want to use the circuit below to detect undervoltage at the input. I don't have any other supply but the input voltage, so I should use the input voltage as supply voltage. The problem is that the ...
Erfan Mirhoseini's user avatar
2 votes
0 answers
135 views

How to keep the reference voltage constant for comparator?

I want to build a circuit with a comparator, but the reference voltage is changing (CH3-purple) as seen in the oscilloscope image. I used the TL431 as in the image to keep the reference voltage ...
avni's user avatar
  • 21
6 votes
2 answers
1k views

Is this TL431-based overvoltage limiter circuit alright?

I have a supply rail that is 15 V nominally +/- 5%. So the highest nominal voltage is 15.75 V. Due to external fault currents of up to 200 mA, the voltage on this rail can rise anomalously. The fault ...
tobalt's user avatar
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0 votes
1 answer
117 views

Can any one explain what type of compensation is this

I will be using the UC3844 controller IC in combination with TL431 to achieve peak current mode control in a 150W forward converter. After some research, I found this schematic on the internet: There ...
tinkerer's user avatar
  • 180
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0 answers
541 views

Using UC3844 and TL431 to compensate a forward converter

I am designing a forward converter capable of providing 5A at 30V at the output. For the compensation part, I am thinking to use UC3844 in combination with TL431 to achieve peak current mode control. ...
tinkerer's user avatar
  • 180
0 votes
1 answer
305 views

TLV431 based voltage regulator, possibility of exceeding Vka max. at startup

I need a small (15mA max.) voltage regulator and considering a TLV431 + emitter follower: This works fine but the datasheet states Vka as 7V absolute max. My input voltage Vi however can be as high as ...
Unimportant's user avatar
  • 4,683
1 vote
2 answers
3k views

flyback converter closed loop by using TL431

I have some things I can't understand when I use a TL431 to compensate for the flyback converter. This picture is from RICHTEK Feedback Control Design of Off-line Flyback Converter. According to this ...
Jitter456's user avatar
  • 575
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0 answers
72 views

TL431 Resistor Choice

I read the Christophe Basoo article The TL431 in Switch-Mode Power Supplies loops: part II About how to choose the resistor I have some questions I would like to ask. On page 13 and page 14 (Watch the ...
Jitter456's user avatar
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0 votes
2 answers
1k views

What's TL431 Output voltage

I am using PSIM to simulate the TL431, and I have some questions. This is my PSIM circuit: When Vref is less than 2.5V, the TL431 doesn't conduct, it looks like an open circuit so Vo is almost 5.1V. ...
Jitter456's user avatar
  • 575
0 votes
2 answers
172 views

LED resistor in the TL431

I read the Christophe Basso APEC 2011 seminar, about this figure I have one question. 1.) Why RLED,max need to below this equation(Red line), what happen if RLED above this equation(Red line)
Jitter456's user avatar
  • 575
0 votes
1 answer
80 views

TL431 Extracting the Pole

I read the Christophe Basso APEC 2011 seminar, about this figure I have some things I can't get it. 1.)Why should need to put the Cdc capacitor in the circuit, what's this function? to block the DC ...
Jitter456's user avatar
  • 575
0 votes
1 answer
327 views

TL431 Type2 Compensator derivation

I am trying to derive the Type 2 Compensator by using TL431, and I read the C.Basso document and I know how to derive the Type 1 Compensator, but I don't know why adding the capacitor (C2) at the Vfb ...
Jitter456's user avatar
  • 575
8 votes
2 answers
1k views

TL431 fast lane and slow lane

I read AN_201610_PL16_01 (Using the IRS2982S in a PFC Flyback with opto-isolated feedback) from Infineon. I would like to know what the fast lane and slow lane are. The document doesn't explain it in ...
Jitter456's user avatar
  • 575
0 votes
0 answers
251 views

TL431 small signal analysis

I read the Chris Basso APEC 2010 I don't understand why the C1 can connect the Op amp output directly when using the TL431. Because the TL431 output has a BJT.
Jitter456's user avatar
  • 575
2 votes
1 answer
734 views

TL431 output voltage

Recently, I use the Tl431 to be a regulator, and I want to change the output of TL431. I read the TI datasheet if I want to change the output I need to change the divider resistor, and I also use PSIM ...
Jitter456's user avatar
  • 575
3 votes
2 answers
976 views

Is this component in falstad a tl431

I'm self studying electronics, I am now familiarizing myself with the tl431, which is pretty much a "variable zener" aparently. I was shown the following symbol. I would like to simulate ...
Joaquin Brandan's user avatar
0 votes
2 answers
1k views

Getting a higher voltage from TL431 in a crowbar circuit

I want to protect a circuit from overvoltage using crowbar circuit, the input voltage shouldn't get above 50 V. TL431 output is 36 V max, can a zener diode in series like schematic below protect the ...
ElectronSurf's user avatar
  • 2,396
1 vote
1 answer
379 views

TL431 vs. SMPS transient response

I am currently working with few 150 W SMPS designs for industial applications with heavy transient load condition. Current design works well by mean of line/load regulation and device reliability but ...
Dhaval Lalani's user avatar
0 votes
2 answers
2k views

Modifying SMPS power supply to produce a negative voltage

In SMPS power supply that uses a single transistor to generate the switching signal ( no control IC), which component must be modified so the output voltage could be negative? I tried to reverse the ...
Yousef Zidan's user avatar
0 votes
1 answer
897 views

4S Lithium Ion Low Votlage Cutoff

Disclaimer: I'm not an electrical engineer, and most of what I've done so far has been from researching similar designs on the interwebs. I'm just a tinkerer with a soldering iron, so please excuse my ...
DIYWannabe's user avatar
1 vote
1 answer
5k views

LTspice error "could not open Library file" when trying to use TL431 model from TI

I downloaded the LTspice model of TL431 from the Texas Instruments website, but I am not able to simulate the circuit given below due to this error: "could not open Library file" https://www....
SAM1's user avatar
  • 21
1 vote
1 answer
141 views

Powering TL431 from MCU output possible?

I'm designing a board with ATmega128 MCU. I have a TL431 reference connected to the ADC_REF pin, with both TL431 and the MCU connected to the same supply, 3.3 V. Now I realized one problem - since ...
simonov's user avatar
  • 121
2 votes
1 answer
1k views

TL431 Loop Compensation

I'm trying to understand this material from C.Basso regarding TL431 compensation (Designing Compensators for the Control of Switching Power Supplies If you refer to pg.110, there is one example ...
Lutz Fi's user avatar
  • 377
5 votes
1 answer
782 views

TL431 crowbar simulation problem

I'm trying to simulate crowbar circuits, which is mentioned on page 8 of ON SEMI TL431 datasheet (https://www.onsemi.com/pub/Collateral/TL431-D.PDF). I'm using TINA TI for this. There are two circuits,...
Zhenek's user avatar
  • 601
2 votes
2 answers
2k views

TL431 / TLV431 supercapacitor voltage clamping circuit

I have a question regarding a circuit I've been working on for some time. The circuit is based around existing supercapacitor protection modules and uses a TL431 (actually a TLV431 lower power ...
Ryan Barrett's user avatar
8 votes
3 answers
3k views

Crowbar circuit causes unexpected behavior for op amp circuit

I am using an op amp to amplify an input signal from a microcontroller, which in general is working fine. For over voltage protection, I added the crowbar circuit taken directly from figure 32, page ...
Eye of Horus's user avatar
4 votes
1 answer
736 views

I'm trying to build a lipo discharger

The way I want it to work is to slowly discharge the lipo down to storage voltage and then stop. I think the best way to do this is to use a TL431 to control the voltage shutoff and use a power ...
japhillips87's user avatar
3 votes
0 answers
153 views

Ripple in output voltage

I am working on an Active Clamp Forward converter. Schematic is given here: Specs: Output voltage-5V Input voltage 26..42V frequency=500KHz Output power=10W It is working fine in open loop, but in ...
Archit Asthana's user avatar
1 vote
2 answers
745 views

How can I estimate TL431 output voltage swings based on datasheet alone?

I am trying to design a series-pass regulator that brings 12V down to 3.3V. If I see a 20 mA step change in current, I would like to stay within a certain output voltage range (±2%). What parameters ...
Bort's user avatar
  • 1,104