# Questions tagged [hysteresis]

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19k views

### what is “input hysteresis”?

I'm looking at a datasheet for a digital circuit and it specifies that the typical input hysteresis is 100 mV. What does this mean exactly?
3k views

### Can anyone explain why a B-H curve with Hysteresis doesn't result in a highly non-linear input-output transfer function for a transformer?

See the attached picture of a typical hysteresis loop, it is clearly highly non-linear even if you keep the signal small enough to stay out of the saturation region (beyond points b,e). So my question ...
12k views

### Comparator with hysteresis equations

I'm trying to be sure I'm computing the values for this circuit right. Here's an example of the circuit I'm trying to build (it's going in a 12 V DC system, so I filled that in already). I have ...
686 views

### Calculating Slew Rate from a time-constant

I have to choose an OP-AMP mainly based on slew rate. I am using the op-amp as a differential comparator with dynamic (time) hysteresis with a time-constant 3*tau=500µs. My upper threshold of the ...
229 views

### Scaling voltage to meet two conditions at once

I am using an IC (STM6600) which, among other functions that I need, is also capable of Undervoltage Monitoring. It works like this: The IC monitors VCC in comparison to two thresholds, V_Low and ...
2k views

### Hysteresis calculation for “open-collector output comparator” with a pull-up resistor

Standard comparators such as LM2903 and LM311 have open collector outputs. I see many times the output of these comparators are tied to Vcc by a pull-up resistor (e.g. in a Schmitt trigger case). ...
362 views

### How do I calculate the hysteresis losses of a straight line inductor?

In using a particular type of conductor for an antenna in AC frequencies between 3MHz and 30MHz (HF), it was suggested that magnetic hysteresis losses may be significant if the permeability of the ...
521 views

### Can a MOSFET be on if there is no current flowing through it?

I am reading about hysteresis comparator here and wondering if a MOSFET can be on if $V_{gs}$ is larger than threshold voltage but there is no current flow through it ($V_{ds}$ is zero), As you ...
349 views

### What is the common name for this seal-in relay?

I'm trying to build a hysteresis water pump system with 2 water level switches. Please see the diagram and explanation of this setup I've taken off the web: The first switch (L) is set at the minimum ...
660 views

### Magnetic field strength and flux density from hysteresis curve

I am trying to measure the magnetic hysteresis curve of a toroidal nanocrystalline ferromagnetic transformer core made of Nanoperm (datasheet linked) using the following circuit. Each of the windings ...
78 views

### Questions regarding eliminating hysteresis in ac dimmer

In the following circuit it says: “This hysteresis effect can be eliminated however, using the circuit from a detailed application note from Littelfuse shown in Fig. 6.4.4. Here the capacitor C1 is ...
610 views

### Output of LM393 won't swing LOW unless it is pulled up with a LED

I built the following circuit using an LM393 as part of a noise gate for audio applications. It's a voltage comparator with hysteresis. I originally connected a 10 kΩ pull-up resistor and then ...
1k views

### Why does hysteretic current-mode control have variable switching frequency?

This figure below is from Raymond B. Ridley Dissertation "A New Small-Signal Model for Current-Mode Control". Here is an except from the document: The general implementation of hysteretic current-...
1k views

### What is the drawback of a high-value resistor for positive comparator feedback / hysteresis?

I'm building a simple circuit which has an LM211 comparator at its heart. The positive input is connected to a 10k-10k resistor divider across the supplies, stabilized by a 1uF capacitor. Hysteresis ...
1k views

### Is there a clever way to prevent a window comparator from oscillating?

Here is my schematic It's basically a crude battery level detector (I am very aware that this isn't the best way to guage battery life, I'm not here for that) it's not crucial that it is super ...
540 views

### Simple circuit reacts to touching a node

I am trying to repeat a circuit from this post. For some reason it does not work properly, and trying to fix it I figure out strange behavior. LED turns on if I touch R3 with my finger or with ...
637 views

### How to derive the node voltage for this comparator with hysteresis?

I have the following circuit. U26 is a simple unity buffer and U15 is just a dual comparator. I want the top comparator to compare the battery voltage (VBAT/2) on the inverting input with 2.0V ...
1k views

### Adding hysteresis to a window comparator

I have designed a window comparator and am finding it seemingly impossible to add hysteresis. Below is the basic circuit before attempting to add hysteresis. Now I add a feedback resistor to the ...
888 views

### Intuitive explanation for this hysteresis circuit?

simulate this circuit – Schematic created using CircuitLab I am trying to get an intuitive understanding of this small circuit. I have both breadboarded it to look at behavior on a scope and ...
375 views

### How significant are hysteresis losses in iron wires with RF currents?

I understand that iron isn't a great choice of conductor for RF currents, as a wire dipole antenna for example. I understand there are several reasons, but I'm wondering specifically about one: ...
82 views

### Comparator circuit undesirable fluctuations

I have designed a comparator with hysteresis and rail to rail operation and my output depicted in figure1.The inputs of the comparator is a sine wave signal and a triangular waveform as shown below....
2k views

### Battery charging and discharging problem

I have designed a battery charging and discharging circuit. The main purpose of this circuit is to charge the battery and then discharge, one operation at a time. I have also added a hysteresis of 3....
2k views

### Techniques for analyzing Comparator circuits?

I'm looking for some general guidelines/equations I can use to analyze circuits which use comparators. In particular, I'm interested in hysteresis. For example, take the following open collector/...
49 views

### What is a suitable hysteresis value and averaging period for a residential thermostat?

I've built a microcontroller based thermostat that I am using to control my home HVAC system. The actual programming and physical assembly has been straightforward. I'm using DS18B20 sensors, so I ...
364 views

### How to calculate hysteresis when the OPAMP supply voltage is changing

I have designed a GSM/GPS based tracker which is installed at my bike. But it is draining battery too quickly. So, I want to add a cutoff circuit when the bike is not running(battery not charging) ...
4k views

### Schmitt Trigger Comparator 0 - 5V

I have designed a schmitt trigger circuit using an op-amp where the output switches from 0 - 5V based off an input hysteresis from 2.2 to 2.8V. My circuit correctly switches at the correct voltages ...
122 views

### What causes the uncertainty in the threshold voltage of a CMOS switch?

CMOS switches such as the DG419 have a threshold voltage - i.e. the voltage at which the output state is flipped - which is dependent upon the logic level and the positive supply rail. However, the ...
2k views

### Stable output from a potentiometer [closed]

A recurring problem with analogue potentiometers is to get a stable output that only changes when the pot is actually moved (i.e. it doesn't output a lot of extremely similar values due to noise or ...
822 views

### Hysteresis in a MOSFET's I-V

I've skimmed through several sparse articles online about hysteresis in a MOSFET's I-V characteristics. What I found was sparse, but some articles attribute uneven-ness in the gate structure, causing ...
283 views

### Schmitt Trigger hysteresis

I am studying comparators and Schmitt triggers. And I did not find anywhere how to choose the value of hysteresis. I understand its purpose and I know how to calculate it. But what value is needed for ...
259 views

### Comparing two variable voltages with hysteresis

All of the designs I have seen for adding hysteresis to a comparator (Schmitt triggers) assume that one of the two inputs to the comparator is set at a fixed reference voltage (typically with a ...
344 views

### Feedback capacitor in comparator circuit with an OP-AMP

Greetings, This is a scheme of a comparator with dynamic hysteresis. Green line is the output Red line is the input Blue line is the positive feedback. I want to ask for the explanation why C1 does ...
139 views

### USB-UART FTDI chip VIH

I am working with an FTDI "FT232R" IC [USB to UART conversion], and struggling to understand what the VIH spec of the IC is. I can only find reference to an 'Input switching threshold (VIN)' spec in ...
45 views

### Op Amp Output Voltage with Hysteresis

so I have to design a circuit which lights up 2 LEDs depending on the output voltage of the Non-Inverting Amplifier. I haven't connected the LEDs in the circuit below because it's not part of the ...
683 views

### How to design a comparator using op-amp?

Intention is to design a comparator with following specification: Input: 0V to 1.65V, Output: Low Input: 2.1V to 5V, Output: High This is the TI design doc I have refereed for the design. Please ...
47 views

### -Ve feedback comparator and its threshold values?

I was trying to analyse and understand the following circuit. My intention was to calculate the hysteresis of the comparator. Circuit working: For both compartor input, there will be voltage inputs ...
154 views

### Is this AN on comparator with hysteresis wrong?

Reading this datasheet of the LM94022, chapter 8.3, where is shown the following example: I don't know how they get the formulas. I more agree to achieve something like this: taken from this answer. ...
2k views

### Adding hysteresis to MOSFET used as a switch

I have a low-voltage detection circuit which I use to trigger one of two LEDs (green, and red) that is powered off of a +9V battery cell. As the battery discharges, its output voltage decreases, until ...
124 views

### Schmitt triggers hysteresis symbols

So we're studying Schmitt triggers at university and we got these representations. Searched them on google for more info and got other representations. Now I'm confused. Can anyone help me with some ...
77 views

### Hysterisis - How do you choose a good value for R3?

simulate this circuit – Schematic created using CircuitLab Above is the basic schematic for a comparator with hysteresis. Determining the values of R1 and R2 is fairly straight forward. They ...
70 views

### Magnetic material demagnetization through Curie temperature

It is known that some materials lose their permanent magnetic properties when they are heated above certain temperature known as Curie temperature or Curie point. As those materials are cooled down to ...
45 views

### Op-amp driving mosfet changes hystheresis thresholds?

I have a non inverting push-pull output op-amp with additional hysteresis (Maxim MAX9015) that should drive an N-Mosfet. I calculated the resistor values for the op-amp(R5, R6, R7) for an older ...
249 views

### How to add voltage thresholds with hysteresis to the input of a voltage regulator?

Device to be used in: solar-powered microcontroller with some peripherals attached. Meant to operate whenever sufficient power is supplied (light is bright enough for a while). No battery, weather ...
61 views

### Can I make a peak voltage indicator with a small number of components?

I have a switchmode power supply that rectifies the main voltage with a full bridge rectifier and smoothes it with electrolytic capacitors. Assuming a 115 volt AC power supply, this gives a peak ...
407 views

### How can I calculate the hysteresis of Reed sensor?

As question says, I want to calculate the hysteresis of Reed sensor and I don't know how. As I seen in Reed sensor's documentation, hysteresis may be x/y, or the difference between x and y, and I'm ...
88 views

### Transformer Hysterisis

I have the following circuit to plot X-Y plot in an Oscilloscope to get Hysteresis curve. R2 and C2 are kept so that the cutoff frequency of low pass filter formed is less than 2Hz. ...
463 views

### Glitch vs runt pulse due to hysteresis

This is a conceptual question. What I understand is that runt pulse is like a glitch but its amplitude is less than the main pulse's amplitude. If Im not wrong on this definition, below illustartes ...
3k views

### Hysteresis in CMOS Schmitt Trigger

! How does this circuit work? why do you get different threshold voltages for increasing and decreasing Vin?