| 摘要 |
<p>The invention relates to a polarity protection circuit, which is used in a power supply arrangement where a power supply (101, 107) is connected via supply voltage lines to a load (116, 117). The polarity protection circuit further contains a first protective semiconductor switch, which is a metal oxide semiconductor field effect transistor (110), and which gets its control voltage via a certain connection from said supply voltage lines. The second semiconductor switch is a transistor (113), which also gets its control voltage via a certain connection from said supply voltage lines. If the supply voltage has the wrong polarity the first protective semiconductor switch (110) is kept in the non-conducting state. If for instance in the supply voltage lines during normal operation there occurs a short circuit, which tends to change the direction of the current, then the transistor (113) rapidly discharges the gate charge of the first protective semiconductor switch (110), and the current flow in the wrong direction is prevented.</p> |
