Technological innovation
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Technological innovation
HOTLine：0769-2268 1472
ESR, is EquivalentSeriesResistance three words the acronym translates to "equivalent series resistance." In theory, a perfect capacitor itself does not produce any energy loss, but the actual ESR, is EquivalentSeriesResistance three words the acronym translates to "equivalent series resistance."
In theory, a perfect capacitor itself does not produce any energy loss, but in fact, because the manufacturing capacitor materials are resistors, capacitors have a dielectric loss of various causes capacitance become "perfect." The loss in external performance as a resistor in series with the capacitor together, so it played a called "equivalent series resistance."
ESR capacitor behavior, has led to a departure from the original definition.
For example, we believe that the capacitor voltage is not above the mutation, when suddenly a current is applied to the capacitor, the capacitor because of their charge, voltage will begin to rise from zero. But with ESR, resistance itself will produce a voltage drop, which leads to the voltage across the capacitor will produce mutations. Undoubtedly, this will reduce the capacitance of the filter effect, so a lot of high-quality power it a class, use low ESR capacitors.
Similarly, in the oscillation circuit and other occasions, ESR will cause a change in the functional circuit occurs, causing circuit failure or damage and other serious consequences.
Therefore, in most cases, low ESR capacitor ESR tends to have better than high performance.
But things there are exceptions, in some cases, the ESR has also been used to do something useful.
For example, in the voltage regulator circuit, there is a certain ESR capacitor, at the time of the occurrence of transient load, will immediately generate volatility caused by the feedback circuit operation, the rapid response, transient performance at the expense of certain expense, obtain the follow-up rapid adjustment capability, especially in response to relatively slow speed power MOSFET and capacitor volume / capacity is strictly limited time. This is found in some of the mos tube be adjusted using the three-terminal regulator tube or similar circuit. This time, too low ESR but will reduce overall performance.
ESR is the equivalent of "series" resistance, means that the two capacitors in series, will increase this value, and in parallel will reduce it.
In fact, the need to lower ESR occasions more, and low ESR bulk capacitors are relatively expensive, so a lot of switching power supplies in parallel strategies taken by a plurality of relatively high ESR electrolytic in parallel to form a large low ESR capacitance. PCB sacrifice some space in exchange for reducing the cost of the device, it is often cost-effective.
Another concept is similar and ESR ESL, which is the equivalent series inductance. Early roll often has a high inductance ESL, and greater capacity capacitor, ESL generally greater. ESL often become part of the ESR and ESL will lead to some electrical fault, such as the series resonance and the like. But the relative capacity, the proportion of ESL is too small, a very small chance of problems, coupled with advances in capacitor production process, is now gradually ignored ESL, while the ESR as an addition to the capacity factor of the main reference.
Incidentally, there is also a capacitance and inductance similar quality factor Q, the coefficient inversely proportional to the ESR, and frequency dependent, relatively small use.
Circuit faults caused by the ESR is often difficult to detect, but also affect the ESR can easily be overlooked in the design process. Simple approach is the simulation time, if you can not select specific parameters capacitor, the capacitor may try artificial series resistor to simulate the impact of a small ESR, usually, the tantalum capacitor ESR usually 100 milliohms or less, The aluminum electrolytic capacitors is higher than this value, some species capacitor ESR even up to several ohms.
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