Common test methods for Schottky diode voltage drop

Common test methods for Schottky diode voltage drop

The advantages of Schottky diodes are low impedance, small forward voltage drop, and fast recovery speed, so they are often used in high-frequency high-current rectification and power-down protection circuits. Schottky diodes have a fast recovery speed and can be used in high-frequency applications, so switching power supplies use such diodes for rectification output. However, the temperature of the rectifier tube on the switching power supply is still very high.

     Common test methods for Schottky diode voltage drop

     Test with "DCPOWERSUPPLY" instrument (constant current regulated DC current): first apply a small voltage to allow current to pass through the Schottky diode, then slowly increase the current to reach the rated current of the Schottky diodes under test, and wait for the voltage value to stabilize. Read again, and the stable reading is the voltage drop of the rated current.

     Why is the stable voltage reading the correct voltage drop reading: The impedance of the Schottky diodes is not fixed, but decreases with increasing temperature (non-linear relationship).

     When a current passes through the Schottky diodes, the tube core will generate heat, which will then be dissipated through the tube body. When the heat balance is reached (the heat generated by the tube core can be dissipated in time), the impedance at this time is relatively stable, which is Law of conservation of energy (P=I2R, P is converted into heat). If the rated current is used to test directly, the initial reading is high, because the die at this time is in a normal temperature state, and the impedance is the largest, and the reading will gradually decrease over time, because the impedance becomes smaller as the temperature increases.

     Common Mistakes in the Test Method of Schottky diode voltage drop

     Some users directly use a multimeter to test due to the limitation of the test equipment. Although the multimeter has a gear for testing diodes, its output current is only one or two milliamperes. The reading of the test is not "internal resistance", but the current It is the voltage drop at the milliamp level, and the readings displayed when testing the voltage drop of each batch of Schottky diodes with this method may deviate greatly. Schottky diodes usually work at the ampere level, and the difference between the two thousand times.