Ceramic Capacitor Leakage Current

Apart from selecting the perfect capacitor with proper leakage circuit should also have the ability to control the leakage current.

Ceramic capacitor leakage current.

Aluminium electrolytic capacitors have a large leakage current while ceramic foil and plastic film capacitors have small leakage currents. A ceramic capacitor is a fixed value capacitor where the ceramic material acts as the dielectric. Therefore the value of the flowing current varies depending on the amount of time voltage is applied to the capacitor. I have two ceramic capacitors mlcc of same rating 10v 100uf x5r one in 1206 package c3216x5r1a107m160ac and the other one in 1812 package c4532x5r1a107m280kc.

Also to make matters worse the ltc1966 needs a 1uf or greater capacitor at its output. The leakage current can be estimated as follows from the insulation resistance specification value and the rated voltage of the item using the formula i v r. The datasheet for a ceramic capacitor states the guaranteed minimum insulation resistance or insulation resistance limit in ohm farad ω f in terms of the case size and capacitance value. Which one will have more leakage at an application voltage of 5 vdc and why with possible reference please.

The leakage current of capacitor is a crucial factor for the application especially if used in power electronics or audio electronics. These ac losses are nonlinear and may depend on frequency temperature age and for some special types on humidity. The amount of leakage current varies from one type of capacitor to another depending on the characteristics of the dielectric material and construction. Capacitor leakage current is an important parameter in amplifier coupling circuits or in power supply circuits with the best choices for coupling and or storage applications being teflon and the other plastic capacitor types polypropylene polystyrene etc because the lower the dielectric constant the higher the insulation resistance.

Leakage current is a constant current flowing after a certain period of time when the influence of absorption current diminishes. Dc losses are specified as leakage current or insulating resistance and are negligible for an ac specification. Leakage current specification values are not prescribed for dc and are instead specified by the insulation resistance value. As the charging current and absorption currents decay the current flowing converges to the leakage current.

Different types of capacitors provide different leakage current ratings. The ltc1966 has an unfortunately high output impedance 85kohms. The leakage current of the ceramic capacitor is extremely small so the insulation resistance parameter is used to indicate its insulation performance.