Electrostatic discharge protection device for integrated circuit
First Claim
1. An ESD protection arrangement comprising an IC device and first and second ESD protection circuits, each of said ESD protection circuits comprising two depletion mode MOSFETs connected in series drain-to-drain between an input terminal and an output terminal of said circuit, each of said MOSFETs having a gate, a body and a source shorted together, a common node between said MOSFETs being connected to ground through a first diode a source terminal of one of said MOSFETs being connected through a series resistor to said output terminal and to a cathode of a second diode, an anode of said second diode being connected to ground, the output terminal of said first ESD protection circuit being coupled to internal circuitry of the IC device, the output terminal of said second ESD protection circuit being coupled to a power supply rail of said IC device.
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Accused Products
Abstract
An electrostatic discharge (ESD) device includes a pair of depletion mode MOSFETs connected drain-to-drain in a series path between an input terminal and an output terminal, the gate of each MOSFET being connected to its source. A first diode having a relatively high breakdown voltage is connected between ground and the common drain terminal of the MOSFETs, and a second diode having a relatively low breakdown voltage is connected between ground and the output terminal of the device. The second diode breaks down during a relatively low, long-lived voltage spike (in an automobile, sometimes referred to as a "load dump"), while the second MOSFET saturates, limiting the size of the current through the second diode. The first diode breaks down during a large voltage spike of short duration, such as occurs from an ESD.
74 Citations
26 Claims
- 1. An ESD protection arrangement comprising an IC device and first and second ESD protection circuits, each of said ESD protection circuits comprising two depletion mode MOSFETs connected in series drain-to-drain between an input terminal and an output terminal of said circuit, each of said MOSFETs having a gate, a body and a source shorted together, a common node between said MOSFETs being connected to ground through a first diode a source terminal of one of said MOSFETs being connected through a series resistor to said output terminal and to a cathode of a second diode, an anode of said second diode being connected to ground, the output terminal of said first ESD protection circuit being coupled to internal circuitry of the IC device, the output terminal of said second ESD protection circuit being coupled to a power supply rail of said IC device.
- 2. An ESD protection arrangement comprising an IC device and first and second ESD protection circuits the first ESD protection circuit comprising first and second depletion mode MOSFETs connected in series drain-to-drain between an input terminal and an output terminal of the first ESD protection circuit, each of said first and second MOSFETs having a gate, a body and a source shorted together, a common node between said first and second MOSFETs being connected to ground through a first diode a source terminal of said second MOSFET being connected through a series resistor to the output terminal of the first ESD protection circuit the output terminal of said first ESD protection circuit being coupled to internal circuitry of the IC device, said second ESD protection circuit comprising a third depletion mode MOSFET connected between an input terminal and an output terminal of said second ESD protection circuit, said third MOSFET having a gate, a body and a source shorted together, a drain of said third MOSFET being connected to ground through a second diode a source terminal of said third MOSFET being connected to an output terminal of said second ESD protection circuit, the output terminal of said second ESD protection circuit being coupled to a power supply rail of said IC device.
- 3. An ESD protection circuit for protecting internal circuitry of an IC device, said circuit comprising an input terminal, an output terminal to be connected to the IC device, a depletion mode MOSFET, said MOSFET having a gate, a body and a source shorted together, and a drain connected to ground through a first diode a source terminal of said MOSFET being connected to the output terminal of said ESD protection circuit and through a series resistor to a cathode of a second diode, an anode of said second diode being connected to ground.
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12. An ESD protection arrangement comprising an IC device and an ESD protection circuit wherein the ESD protection circuit comprises two depletion mode N-channel MOSFETs connected in series drain-to-drain between a tri-state buffer and an input/output terminal of the IC device, each of said MOSFETs having a gate, a body and a source shorted together, a common node between said MOSFETs being connected to ground through a first diode, a source terminal of one of said MOSFETs being connected through a series resistor to the tri-state buffer and to a cathode of a second diode, an anode of the second diode being connected to ground.
- 15. An ESD protection circuit comprising an input terminal, an output terminal, a depletion mode MOSFET connected between said input terminal and said output terminal, the source, body and gate of said MOSFET being shorted together and connected to said output terminal, a first diode having a cathode connected to a drain of said MOSFET and an anode connected to ground, and a second diode having a cathode connected to the output terminal and an anode connected to ground.
Specification