Input protection device with Zener diodes for electronic device
AssigneeNissan Motor Co., Ltd.
InventorKoichi Murakami
Life of this patent
Estimating the term…
Abstract
An input protection device comprises a current limiting resistor externally connected to an integrated circuit which includes two Zener diodes, one functioning as a power supply Zener diode and the other functioning as a ground Zener diode. Owing to the resistance of the current limiting resistor and junction capacitances of the Zener diodes, electromagnetic interference noise is effectively damped or attenuated.
Claims11
In an input protection device adapted to be connected between a plurality of independent switches and an electronic device and circuited between a power supply and ground, each of the independent switches being connected to the ground;
- a circuit comprising:
- a semiconductor substrate;
- a plurality of pairs of first and second Zener diodes in said semiconductor substrate, said plurality of pairs being adapted for connection with the plurality of independent switches, respectively;
- each of said plurality of pairs having an anode of said first Zener diode thereof adapted to be connected to one of said plurality of independent switches and a cathode of said first Zener diode thereof adapted to be connected to the power supply, and having an anode of said second Zener diode thereof adapted to be connected to the ground and a cathode of said second Zener diode thereof adapted to be connected to said one switch;
- said first Zener diodes and said second Zener diodes of said plurality of pairs being arranged in an interleaved manner.
Between an electrical device receiving an input signal on an input line, a protection circuit comprising:
- a first Zener diode having a cathode thereof connected to an electrical source and an anode thereof connected to said input line;
- a second Zener diode having a cathode thereof connected to said input line and an anode thereof connected to ground;
- a bias resistor connected between said input line and one of said electrical source and ground;
- a comparator for receiving a voltage from said input line and a reference voltage;
- and
- at least said first Zener diode, said second Zener diode, said bias resistor, and said comparator being formed on a semiconductor substrate, said protection circuit being connected in series with a protect resistor on said input line such that said protection circuit is arranged between said electrical device and said protect resistor and an input connector is disposed on said input line between said protect resistor and said protection circuit.
An input protection circuit between a switch and an electrical device, comprising:
- a current limiting resistor having one end connected to the switch and an opposite end;
- a first Zener diode having a cathode thereof connected to an electrical source and an anode thereof connected to said opposite end of said current limiting resistor;
- a second Zener diode having a cathode thereof connected to said opposite end of said current limiting resistor and an anode thereof connected to ground;
- a bias resistor having one end thereof connected to said anode of said first Zener diode and to said cathode of said second Zener diode, said bias resistor having an opposite end thereof connected to one of the electrical source and ground;
- and
- a comparator;
- said comparator including a first input and a second input, a voltage at said one end of said bias resistor applied to said first input and a reference voltage applied to said second input, said comparator being connected between said one end of said bias resistor and the electrical device;
- at least said first Zener diode, said second Zener diode, said bias resistor, and said comparator being formed on a semiconductor substrate.
Dependencies are inferred from the claim text.