What is the meaning of the ESR of the capacitance (II)

For example, in a voltage stabilizing circuit, the capacitance of a certain ESR will produce a feedback circuit action when the load occurs instantaneously. This fast response, at the expense of a certain transient performance, gets the subsequent quick adjustment ability, especially the slow response speed of the power tube, and the capacitance. The volume / capacity of the device is strictly limited. This is seen in some three terminal voltage regulators or similar circuits using MOS tubes as adjustment tubes. At this time, too low ESR will reduce overall performance.

ESR is equivalent to "series" resistance, which means that connecting two capacitors will increase this value while parallel will decrease.

In fact, more places need lower ESR, and the low ESR capacity of large capacity capacitance is relatively expensive, so the parallel strategy of many switching power supplies is parallel to the relatively high aluminum electrolysis of multiple ESR to form a low ESR capacity of large capacity. Sacrificing a certain PCB space to reduce device cost is often cost-effective.

Another concept similar to ESR is ESL, which is equivalent series inductance. The inductor of the early winding often has a very high ESL, and the larger the capacitance is, the larger the ESL is. ESL will often become part of ESR, and ESL will also cause some circuit faults, such as series resonance. But relative capacity, the proportion of ESL is too small, the probability of problems is very small, coupled with the progress of capacitive manufacturing process, now gradually ignored the ESL, and the ESR as a major reference factor in addition to capacity.

Incidentally, the capacitor also has a quality factor Q similar to inductance, which is inversely proportional to ESR, and is related to frequency and is less used.

The circuit fault caused by ESR is usually difficult to detect, and the influence of ESR is easy to be neglected in the design process. In a simple way, at the time of simulation, if the specific parameters of the capacitor can not be selected, a small resistance can be tried to simulate the influence of ESR on the capacitance. Generally, the ESR of the tantalum capacitor is usually below 100 millieu, and the aluminum electrolytic capacitor is higher than that, and the ESR of some kinds of capacitance will reach even high. A number of ohms.