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I think the spikes are a natural result of the hard switching from the switch causing a sudden flow of excess charge into and out of the capacitors. One possible solution could be to increase the size of the caps, or to ramp the switching process by putting a filter at the switch.
The decoupling capacitor provides a resivour of current that is instantly avilable at the swithing component removing small spikes and glitches from the power rail. Any small imperfections on the power rail can cause iregular operation of the circuit. Barrybear
As a rule you receive spikes via your ground line Optocoupler will not help if you have the same gnd for power driver and your control unit Try to use optocouplers for in/out + floating power supply placed close to uC it will work for sure. try to connect two gnd's via 0.1u capacitor, sometimes it is better than "absolutly" floating power
Sometimes there occur spikes in the waveform that is difficult to detect and eliminate like in the figure. How can we eliminate them? I have an encoder that produces pulses like in the figure. I filter encoder output with an rc filter. But sometimes it doesn't work correctly. I couldn't catch the error source because it rarely happens. I suppose t
Hi all I have completed the design of the basic S/H stage of a 1.5Bit pipelined ADC converter (VDD=1V, Fclk=40MHz, Input signal swing 0.25V-0.75V). After simulations i have noticed that when the input is quantized, except the steps in the output i get spikes during the transitions of the clock which can be as large as 50-60mV. Is this normal
Use one 100uF/16V and one zener diode (5.6-6.2 Volt/1W) at 5 Volt rail (output) i can only imagine this..could u upload the diagram please..? You only show a regulator for the positive side. If you don't need a negative output, then eliminate the 47uF capacitor, and don't use the lower 2 diodes of the bridge i
Decoupling capacitors are there to ensure that no paracitic DC components will be propagated to the rest of the circuit or inside the IC. It is clearly for protection reasons for both sides. As for the applied distance I will support the other two posts. Try to do this: every time there is an unexplainable issue, go to the very basics of elr
Hi I think your problem is "clock feed through". connect a capacitor to gate of M5. (cap must be between gate of M5 and Gnd) maybe it reduce spikes. regards
What is the main contribution of LDO's large external output capacitor? Better transient response or low output noise? Or other reason? What about some on-chip LDO with small (<100pF) onchip output capacitor,do they have sever problems?
Where ever you get a very high speed swithing junction you will get a spike. try a little decoupling. Shunting with a small capacitor.Diodes can also help as clamps,
Hi everyone, I have a problem with a power supply, the varistor and ceramic capacitor is oftenly burnout. I have replace it with the same type its working normally, but not in along time (2 - 3 days), then its burned again. can everybody tell me the cause of capacitor and varistor burnout. thank you. sorry for my english. images.
I have problems filtering the spikes that are created by fast switching components. I have two examples. First one is a 1MHz cmos type logic gate switching. As you can imagine the power is low in this scheme. It can easily be filtered by a low pass filter or a single proper capacitor. But the second one is a power supply switching scheme. Although
We are designing some DC-DC converter circuits.We have used the boost, Flyback and Sepic configurations. We have used LC filters and capacitor filters to suppress the switching noise and to meet the EMI/EMC requirements. The noise is getting suppressed by the filter, but there are unwanted spikes at the rising and falling edges which are of cons
Hi. I am simulating the switch capacitor circuit to realize a resistor (say). The operation is as follows: On phase phi1, V1 is sampled across capacitor C. The next overlapping phase phi2, V2 gets sampled. The difference of these voltages causes the current flow. Its all quite simple. When I simulate with all the ideal components in spectre, I get
The spikes at primary side are caused by a specific problem of your design, I already mentioned, see above. The spikes at the output are visible either cause the output capacitor has a high series inductance or are possibly measurement artefacts. The current waveform is basically O.K., also the primary voltage (apart from the (...)
The continous switching of coils inside the motor would produce all kinds of brief high-frequency pulse currents. The capacitor close to the motor will discharge and deliver some energy to satisfy these current pulses, so that they don't need to draw current through the long (inductive) cables, with all kinds of radiated noise as a result.
Physically, all the capacitors are same, only their functionaliyt is application specific. When capacitor is used in between two stages for removing the DC components from the signal, it is called coupling/decoupling capacitor. When capacitor is used to bypass the AC signal component across any circuit, it is called bypass (...)
This capacitor is known as decoupling capacitor, the purpose of using this capacitor in parallel with a permanent Magnet DC motor is to block the inductive kicks generated as the rotor moves + it enhances the commutator life by preventing the spark between the commutator & brushes. if its a simple toy then there is no need for a filter (...)
I have modified your circuit slightly: 1. I have reduced the maximum time step so you get a clean sine in the simulations 2. I have added a load switch to do a stability check. The current "spikes" are really just the top part of a sine wave when the capacitor charge is topped up. They are inevitable, but you need to make sure the capacit
a good trick is to get a length of 50 ohm microstrip line, and place 5 capacitors in series with some spacing in between. Then just run an insertion loss measurement. If they stink, you will have considerable roll off at higher frequencies and some insertion loss spikes.
if the motor speed control is thro pwm , capacitor across the motor is not necessary.
u said "In general, in the chip spare space we add moscap(gate connect to one power rail, and source-drain connect to the other power rail) for decoupling as moscap has most unit capacitor?' why do we use unit capacitor ? for example, why not use one big mos cap? why use large capacitor by parallel unit cell?
Hi guys , in one of the electronic circuits , i found a capacitor parallel to LED. What is the actual function of capacitor across led -> ESD protection ? -> To increase the turn off time of LED ? Help me to understand this ciruit
Suppose we have a circuit of a Tx buffer connected to an Rx buffer - parallel to the Rx buffer there's a small (200 pF) capacitor shorted to ground. What is the purpose of this capacitor ? What effect will it have on the signal ?
2-3V spikes are much larger than normal. "Isolate" the input of the regulator from the input voltage with a diode and use a large bulk capacitor. Use a small electrolytic capacitor (10uF to 68uF) from VIN to ground and another from VOUT to ground. Use 0.1uF capacitors from VIN to ground, VOUT to ground and also before the (...)
I am working on a circuit which discharges a capacitor charged to around 400 volts using a IGBT (acting as a switch) through a soleniod coil connected to a plunger to dissipate energy mechanically. The IGBT used is FGA25n 120. L293D motordriver is used with a microcontroller to provide gate voltage of 12 volts whenever microcontroller gives high to
we don't see your circuit but one way to remove spike is using capacitor.
capacitors are inexpensive. They are labelled with value and voltage rating. They are easy to keep organized. I can store a large assortment of them, and find a value I need. The operation of capacitors is easier for us to grasp, than inductors. It is easier to use capacitors in circuits, with more likelihood the circuit will work even if (...)
Hi, I have a simple question: I want to make an audio filter using switched capacitor filters (LMF100 - national). There is one problem however: I know I need to use a Bessel filter, but in the specs of these filtes, they don't say how you can create a bessel or butterworth filter. I guess it has something to do with the Q factor. Does anybody h
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I have some bad experience with tantalum capacitor (tp)on board after leaving it for about a year or two: 1. While I'm trying to revive an old pc board, two of the tps exploded. I thought something wrong with the board. 2. I'm trying another board, samething happened. 3. While I'm trying to power up my home build variable power supply uni
If I control a relais from my circuit then I use a diode for protection against high induction voltage upon reset. What if I control 230VAC solenoides with a relay contact? A diode can not be used here. A capacitor maybe?
Use ADS and introduce your S-parameters along with the circuit model for the capacitor. Simulate over your range of frequencies, and optimize for the two goals: 1) S11_measured - S11_calculated 2) S21_measured - S21_calculated Of course you have the parameters in your circuit model as variables. This will match the curves and at that poi
Hi, look at this application note by National Semiconductors It decribes an ultra-high isolation amplifier powered by an ultrasound transducer (!). The input side voltage is converted to frequency then opto coupled to a frequency to voltage converter. Instead of using such a transformer for input side power supply, you c
Try , and into the component division. I think if you use these capacitor in ac line in, you must choose x1 or x2 type capacitor (for safty purpose).
Hi, I thought these little Matlab programs were pretty useful. Say you want to find a resistor value combination that most closely approximates a particular divide ratio, or whatever other function you can think of for r1 and r2. Given discrete values in your kit, which two will get you the closest? Or say you want to pick a resistor an
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The diode is reverse biased when the switch is closed and so with an ideal diode you get the full 10 V on the output. (If the diode were not ideal, you would get the 10 V minus the diode leakage current drawn through the resistor.) If the diode was the other direction, the output would be the diode forrward drop plus the voltage on the capacitor.
Normaly, for decoupling capacitor in digital purposes, capacitors you can't are electrolitics, because it have a high inductando, so for high frecuencies over 1Mhz, electrolitics capacitors lose the capacity. Use of ceramic or polyesters capacitors are good for decoupling. In picture,it is apparently a NP0 ceramic (...)
Hi, Anybody got any application note on capacitor selection or an introduction to different type of capacitor ? Out of the 3 type of dielectric X5R, X7R & CG0 (NP0), which one is the cheapest in term of cost ? Next, which footprint (0402, 0603, 1210 & etc) is the most common on PCB ? Thanks a million in advance ! Best Regards
How to simulate their noise in switched-capacitor circuits? who know?
Hello, I have some problems for chip capacitors. Currently we are using some "quality" chip capacitors, such as Kemet and Phycomp (Ex philips). But I find them easily short circuit after wave soldering. Especially if the pcb is placed at high humidity environment. The problem seems to be caused by not enough acid cleaning from the (...)
I want to bypass the unwanted frequence , so i use the cap. but How can i learn the self resonance of a SMT capacitor ? for example , i want to filter out some frequences on the power supply of GSM900&1800&1900. see it at the data sheet
How to simulate Switched-capacitor Circuit in the frequency domain using spice? ynhe
Hi, Decoupling capacitors should be placed first of all near the IC pins. If the DC source is a cable (from external power supply) or voltage regulator, additional decoupling capacitor should be placed where the cable enters the PCB (to filter noise at the input) or near the voltage regulator output (to decrease the noise that voltage regulator ca
In digital or analog circuits there is a possibility of parasitis couplings between IC's or stages over the supply line. Result is often erratic operation or even oscillations. To aviod such a problems decoupling is used. At each digital IC, usually, a 100nF ceramic capacitor os placed accross supply voltage. After few IC's a 1uF or 10uF, tantalum
There are several filtering methods. 1. Put a large shut capacitor on the output line. Parallel it with smaller ones. 2. Use a series inductor shunt capacitor filter. 3. If you can work with a slightly smaller voltage, use a low dropout analog voltage regulator following the supply.
In audio or in measurement applications it is sometimes neccessary to block the DC signal and only to let the AC part of an analog or digital signal pass through a circuit. There you decouple the signal with a series capacitor (high pass filter). Depending on key requirements such as lowest corner freqeuncy of the high pass filter, size of the