Kingtronics Blog

Schottky rectifiers have been used in the power supply industry for approximately 15 years. During this time, significant fiction as well as fact has been associated with this type of rectifier. The primary assets of Schottky devices are switching speeds approaching zero-time and very low forward voltage drop (VF). This combination makes Schottky barrier rectifiers ideal for the output stages of switching power supplies. On the negative side, Schottky devices are also known for limited high-temperature operation, high leakage and limited voltage range BVR. Though these limitations exist, they are quantifiable and controllable, allowing wide application of these devices in switch mode power supplies.

High leakage, when associated with standard P-N junction rectifiers, usually indicates “badness,” implying poor reliability. In a Schottky device, leakage at high temperature(75 °C and greater) is often on the order to several milliamps, depending on chip size. In the case of Schottky barrier rectifiers, high-temperature leakage and forward voltage drop are controlled by two primary factors: the size of the chip’s active area and the barrier height (φB).

The EKT Series is a high temperature version of Kingtronics's solid tantalum chip family that offers optimal performance in applications with operating temperatures of up to 125° C. Advancements in materials and testing have allowed for the introduction of this series which delivers a reliability level of 0.5% per 1000 hours at rated voltage at rated temperature. This series is available in five standard EIA case sizes with RoHSCompliant/100% matte tin finish lead terminations as standard.

Other termination options include 90Sn/10Pb finishes and gold for conductive adhesive attachment processes. Capacitance values range from . 0.33uF - 470uF, in voltage ratings from 4 to 50 volts.

Kingtronics has developed an innovative construction platform that incorporates multiple capacitor elements,in parallel, inside a single package. This unique assembly, combined with Kingtronics’s superior processing technology, provides the best combination of high CV, low ESR, and small size in a user friendly, molded, surface mount package.

The fundamental electrical properties of multilayer ceramic capacitors are as follows:

Polarity: Multilayer ceramic capacitors are not polar, and may be used with DC voltage applied in either direction.

Rated Voltage: This term refers to the maximum con tinuous DC working voltage permissible across the entire operating temperature range. Multilayer ceramic capacitors are not extremely sensitive to voltage, and brief applications of voltage above rated will not result in immediate failure. However, reliability will be reduced by exposure to sustained voltages above rated.

Like all other practical capacitors, multilayer ceramic capacitors also have resistance and inductance. A simplified schematic for the equivalent circuit is shown in Figure 1. Other significant electrical characteristics resulting from these additional properties are as follows：

Impedance: Since the parallel resistance (Rp) normally very high, the total impedance of the capacitor is ：

The variation of a capacitor’s impedance with frequency determines its effectiveness in many applications.