Thanks to their very low equivalent serial resistance (ESR), they provide a very worth function in power supply parts of various devices. In many cases, there´s no need to add any other types of filtering capacitors anymore.
SMD ceramic capacitors are nowadays commonly available in relatively very high capacities of units to tens of uF, while keeping small dimensions (0603 – 1210). There are also available higher capacities in bigger packages, but the offer of producers is especially reach at these small packages (0603-1210) and prices are significantly better in comparison to a recent past.
Why to use a ceramic capacitor? First, it has a substantially lower value of ESR than electrolytic capacitors and also lower than tantalum ones. This is reflected in low losses and outstanding filtering properties even at high frequencies and high currents, what is especially beneficial at power supply of fast semiconductors and in switch-mode power supplies. Low power consumption of modern components enables to decrease an overall capacity of capacitors in a power supply part, that´s why in many cases a few uFarads are sufficient. A big advantage is a long lifetime too, because they don´t contain any liquid electrolyte. Naturally, in devices, where high current peaks occur, it would be economically inefficient to use ceramic capacitors only. In such cases a combination of ceramic and tantalum or electrolytic capacitors is ideal.
In our offer can be found more types, also a novelty in our offer – 2,2uF/10V/0805 from the X7R mass from company YAGEO (please note a significantly lower price at purchase of 50 pcs and more). The X7R mass ensures very good properties in a wide range of temperatures and voltages. Detailed information will provide you the X7R, X5R and Y5V documents. In case of interest about any YAGEO component, please contact us at email@example.com
Do you utilize ceramic capacitors for power supply filtering? - [Link]
Useful life (also termed service life or operational life) is defined as the life achieved by the capacitor without exceeding a specified failure rate. Total failure or failure due parametric variation is considered to constitute the end of the useful life.
Depending on the circuit design, device failure due to parametric variation does not necessarily imply equipment failure. This means that the actual life of a capacitor may be longer than the specified useful life. Data on useful life has been obtained from experience gained in the field and from accelerated tests.
The useful life can be prolonged by operating the capacitor at loads below the rated values (e.g. lower operating voltage, current or ambient temperature) and by appropriate cooling measures. In addition to the standard type series, EPCOS types are available with useful life ratings specially matched to customer specifications.
Calculating the Useful Life of Capacitors - [Link]
Le Hung writes:
LCFesR 4.0 unit is a precise, wide range LC / LCF / LCR / ESR meter (tester / checker) that measures inductance (L), capacity (C), frequency (F), small resistance (R) and equivalent series resistance (ESR) of a capacitor inside an electronic circuit (in-circuit). The meter can be built easily with one- or double-sided PCB and available electronic components (DIY). It’s functions are base on an further developed AVR ATMega88PA-PU microprocessor. Professional KIT is also available.
LCFesR 4.0 meter – LC / LCF / LCR / ESR meter - [Link]
Eric built himself a battery monitoring system based on the ATmega328 Development Kit. He drained a 9V battery with 100mA of current and monitored the voltage drop until total depletion. He used this data to estimate how much time is left until depletion – [via]
The 100mA constant load was chosen because my ProtoStack Arduino Clone with LCD draws about 92mA and I wanted to write a sketch to display a battery bar and the approximate hours battery life left. Since all batteries have an internal equivalent series resistance (ESR), it is important to take that into account when only using a battery’s voltage to monitor its state of charge. Since we discharged the battery through a load that is similar to the ProtoStack board with LCD, the ESR of the battery has automatically been accounted for in the voltage measurements.
Monitoring battery voltage to calculate capacity with an Arduino - [Link]
Arhi made use of his precision LCR meter to measure capacitance and ESR values of ceramic, tantalum, and electrolytic capacitors. He made his measurements at various frequencies to help him graph the changes to the values over a wide frequency range.
From the graph it can be extrapolated that the ceramic capacitors have the lowest ESR values at any frequency up to the measured 100KHz. While the tantalum capacitors seem to be the most stable of the group.
Ceramic, tantalum, and electrolytic capacitor comparison - [Link]
The ESR Meter is basically an AC Ohmmeter with special scales and protective circuitry. It provides a continuous reading of series resistance in electrolytic capacitors. It operates at 100 kHz to keep the capacitive reactance factor near zero. The remaining series resistance is due to the electrolyte between the capacitor plates and indicates the state of dryness. Capacitor termination problems also show up plainly due to the continuous ohmic reading.
AC Ohmmeter – ESR Meter – [Link]
When teamed up with an oscilloscope, this simple circuit provides a means of measuring capacitor ESR. A 555 timer (IC1) configured as a 2.3kHz free-running oscillator acts as the timebase. It provides narrow (7.7µs) pulses to the capacitor under test via a NAND Schmitt trigger (IC2) and transistor Q1. A 100Ω resistor in series with Q1 limits current flow to about 50mA. Therefore, an ESR of 1Ω will produce pulses across the test capacitor of 50mV, which means that an oscilloscope with a vertical sensitivity of 5mV can measure ESR down to 0.1Ω or less.
Oscilloscope ESR Tester - [Link]
A typical capacitor checker measures the capacity (usually in micro farads) of the test capacitor. Some advanced units also test for leakage current. Most of these testers require that the capacitor be removed from the circuit. Unless the capacitor has totally failed, they will not detect a high ESR value. In a typical circuit, there may be 10′s or 100′s of capacitors. Having to remove each one for testing is very tedious and there is a great risk of damaging circuit boards. This tester uses a low voltage ( 250mv ) high frequency (150khz) A/C current to read the ESR of a capacitor in the circuit.
Capacitor ESR Meter – [Link]