Polarity protection implemented with a MOSFET
AssigneeTellabs Oy
InventorSami Jokinen
Life of this patent
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Abstract
A polarity protection circuit contains a metal oxide semiconductor field effect transistor (FET) that pets its control voltage via an electrical connection from supply voltage lines and a transistor that pets its control voltage via another connection from the supply voltage lines. When a supply voltage has a wrong polarity the FET is in a non-conducting state. If in the supply voltage lines during normal operation there occurs a short circuit that tends to chance a direction of the current, the transistor rapidly discharges a gate charge of the FET, and the current flow in the wrong direction is prevented.
Claims4
A polarity protection circuit to be used in a power supply arrangement where a power supply is connected via supply voltage lines to a load, and which polarity protection circuit has a first protective semiconductor switch and a second semiconductor switch, wherein
- the first protective semiconductor switch is a metal oxide semiconductor field effect transistor, which control voltage is taken via a certain connection from said supply voltage lines, and
- the second semiconductor switch is a transistor, which gets its control voltage from a point in the supply voltage line, which point is separated from the first semiconductor switch by an inductance, whereby the transistor is arranged to discharge the electric charge from the first semiconductor switch as a response to a change in the polarity of the voltage between the supply voltage lines.
Dependencies are inferred from the claim text.