Application Notes

Thermal Considerations On Power Semiconductors

The so-called “Arrhenius law” states — in short — that every 10 K increase in temperature reduces the service life of a physical device by 50%. Thermal considerations are therefore essential for power semiconductors. This application note shows how to correctly measure and calculate the junction temperature, provides tips on the correct application of thermal paste, and explains how components must be mounted correctly on the heat sink.

Bypass diodes for solar modules

During construction of solar modules, single cells are switched in series to so called “strings” to achieve higher system voltages.

If one or more cells are shaded (e.g. by branches of trees, antennas, etc.), the affected solar cells are no more acting like a current source, but as power consumers. Non-shaded cells are delivering further current through them, generating high power losses. “Hot spots” may occur and even cell breakdowns.

To overcome this problem, bypass diodes are switched parallel to every single or some combined cells, bypassing current flow across the darkened strings.

Like every semiconductor device, also bypass diodes have got a certain leakage current, which in normal mode of operation reduces the current supplied by the cells and therefore decreases efficiency of the solar module. Therefore leakage current especially at higher temperatures (full sun irradiation!) should be as low as possible. Compared to that, partly shading of modules is only an extreme operation mode which should be completely avoided or at least occurs only during short time periods. For this mode of operation, low forward losses are desirable.

Finally, the bypass diode has to be rugged against overvoltage spikes. Such spikes may occur during assembly of the system, if
e. g. current conducting cables are interrupted, or during operation, caused by lightning etc.

You will find more information in our Application Note Solar Bypass Diodes - you can download the PDF down below.

IGBT - Insulated Gate Bipolar Transistor Roadmap

Silicon Carbide MOSFET Roadmap

MOSFET PDU Power Delivery Unit 100V | 80A

This board is used to demonstrate the use of the Diotec DI280N10TL in a high-power delivery unit. It is capable of switching up to 80 A at 48 V in both directions. This makes it ideally suited for battery systems which need not only to supply power, but also to receive during the charging cycle. Current, Voltage, temperature and operating mode is displayed on an OLED display. Various other Diotec parts such as LDOs, small signal MOSFETs, Rectifier Diodes, Zeners and ESD protection diodes is also used on this module.

Demo Board Wide Input Linear Voltage Regulator LDI55-ADEEN

This board is used to demonstrate the functionality of the LDI55-ADEEN linear regulator. It has wide input range up to 50V, low-dropout (LDO) voltage regulators with enable function and provides up to 1A of output current. Only two small ceramic capacitors are needed to implement the linear regulator solution. The features of low quiescent current as low as 3 µA to 5µA and almost 0.5 µA disable current is ideal for powering the battery equipment to a longer service. Simple device measurements such as line and load regulation, dropout, can be demonstrated with just a single voltage source, a voltmeter, an ammeter, and load resistor.

Battery Management Systems (BMS)

The BMS ensures the safety, longevity, and optimal performance of the battery in the e-vehicle. It helps extend the electric range to 500 kilometers and beyond in modern vehicles. This means that many vacation areas in Italy can already be reached without charging from southern Germany. Typically, the BMS consists of a battery management unit (BMU), sensors, a power stage, and a battery disconnect unit (BDU). The BMU monitors the battery's voltage, current, temperature, and state of charge, while the sensors provide data to the BMU. It also controls the charging process, either through a high-power DC connection or the on-board charger (OBC). The BDU disconnects the high-voltage battery from the vehicle when it is not in use. Diotec's latest application note addresses discrete semiconductor solutions for BMS, such as power MOSFETs, load dump protection, TVS diodes, Schottky, Zener, ESD diodes, and voltage regulators.

On-board charger for electric vehicles (EV)

Most on-board chargers for e-vehicles operate on a voltage of 100-240 volts AC and have an output power of 3-11 kilowatts (kW).

An on-board charger for electric vehicles is a device that is integrated into the vehicle and charges the battery when no charging station or wall box is available.
It works with alternating current and converts it into slip current, which charges the battery. The charger can either be built into the vehicle itself or added as an aftermarket accessory. The voltage and power range of a charger can vary depending on the make and model of the electric vehicle. However, most on-board chargers for e-vehicles operate on a voltage of 100-240 volts AC and have a power range of 3-11 kilowatts (kW).

Silicon Carbide Schottky Roadmap

Parts for high switching frequencies and voltages

Silicon Carbide Schottky diodes feature a high reverse voltage (650 V ... 1200 V) combined with an extremely low "reverse recovery" better say capacitive charge and thus discharging time. That makes these parts ideally suited for all applications, where high voltage levels are switched at very high frequencies. Typical applications include charging systems for electric vehicles (EV), solar inverters or telecom power supplies.