Application Notes

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.

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.

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.

The Enable input (EN), available in positive and negative logic, turns the device on and off by an external signal. Active-high logic activates the device when the voltage at the EN-input exceeds the high-logic threshold. The active-low logic switches the device off when the EN-voltage falls below the logic low threshold. The EN-function is an import- ant feature when sequencing power supplies in multi-rail systems.

When the LDO is turned off and connected to the battery system, the input current will be limited, usually up to 1 µA. This Shutdown current is commonly confused with the quiescent current which is the current drawn by the device when it is enabled and opera- ting with no load. Both shutdown and quiescent current are important parameters when realizing long battery lifetimes in portable devices.