Circuit for overvoltage protection
First Claim
1. A circuit arrangement for protecting a low voltage device, arranged in use to control a load, from an overvoltage condition, includingan input for receiving a load control signal,a low voltage device having a control electrode and coupled across a supply voltage, said low voltage device arranged in use to control a load;
- andswitch means for connecting said load control signal to said control electrode of said low voltage device to control said load;
said switch means being responsive to an overvoltage condition in said supply voltage to disconnect said load control signal from said control electrode and connect said control electrode of said low voltage device to a source of low voltage device on signal to hold said low voltage device fully on and provide a low voltage thereacross to protect said low voltage device and provide overvoltage protection.
2 Assignments
0 Petitions
Accused Products
Abstract
In a circuit for overvoltage protection of a low voltage device (11) arranged to control a load (12) an energy storage capacitor (17) is connected to charge from supply (+V) while the device is controlled from a control circuit (100). During overvoltage, the controller is disconnected by switch means (15) and capacitor connected by switch means (16, 18) across the device to maintain it in an on state so that overvoltage device damage is prevented. The circuit is suited to transitory overvoltage conditions such as automotive load dump and to integration with the controlled device.
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Citations
30 Claims
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1. A circuit arrangement for protecting a low voltage device, arranged in use to control a load, from an overvoltage condition, including
an input for receiving a load control signal, a low voltage device having a control electrode and coupled across a supply voltage, said low voltage device arranged in use to control a load; - and
switch means for connecting said load control signal to said control electrode of said low voltage device to control said load; said switch means being responsive to an overvoltage condition in said supply voltage to disconnect said load control signal from said control electrode and connect said control electrode of said low voltage device to a source of low voltage device on signal to hold said low voltage device fully on and provide a low voltage thereacross to protect said low voltage device and provide overvoltage protection. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 21, 22, 23, 27, 28)
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11. A circuit arrangement for protecting a low voltage device, arranged in use to control a load, from an overvoltage condition, including
an input for receiving a load control signal derived from a first power source signal, a low voltage device having a control electrode and coupled across said first power source signal, said low voltage device arranged in use to control a load; -
means for connecting said load control signal to said control electrode of said low voltage device to control said load; and switch means being responsive to an overvoltage condition in said fist power source signal to connect said control electrode of said low voltage device to a source of low voltage device on signal derived from a second power source signal different from said first power source signal to hold said low voltage device fully on and provide a low voltage thereacross to protect said low voltage device and provide overvoltage protection. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20, 24, 25, 26, 29, 30)
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Specification