US 5,862,031 A · ESD protection circuit for integrated circuits having a bipolar differential input

Abstract

An ESD protection circuit allows a certain level of ESD current to flow through a protected circuit, and actuates a bypass path for greater ESD current levels when the sensed current reaches a threshold level. For a protected circuit having a pair of differential input terminals and a reference voltage terminal, the bypass path is provided between an input terminal which receives an ESD and the reference voltage terminal when the reference voltage is fixed, and between the two input terminals when the reference voltage is floating. The bypass circuit is preferably implemented with a pair of bipolar transistors of a first conductivity that are actuated by an ESD current flow through the protected circuit, and a pair of bipolar transistors of opposite conductivity that are actuated by current flows through the first conductivity transistors.

Claims17

Dependent claims

An ESD protected circuit, comprising:

an electrical circuit to be protected from ESD, said electrical circuit having an input terminal and conducting a progressively increasing current in response to an applied ESD at said input terminal,
a current sensor connected in the path of said progressively increasing current through said electrical circuit, said current sensor developing a voltage that varies with the current through the current sensor, and
a bypass circuit that responds to the voltage developed by said current sensor exceeding a level indicative of an ESD applied to said electrical circuit's input terminal by providing a bypass path for said ESD to prevent it from damaging said electrical circuit.

An ESD protected circuit, comprising:

an electrical circuit to be protected from ESD, said electrical circuit providing an actuation signal in response to an applied ESD, and
a bypass circuit that responds to said actuation signal by providing a bypass path for said ESD to prevent it from damaging said electrical circuit, said bypass circuit comprising a pair of bipolar transistors of a first conductivity connected to be actuated by a current flow through said electrical circuit, and a pair of bipolar transistors of opposite conductivity and connected to be actuated by current flows through said first conductivity transistors.

An ESD protected circuit comprising:

an electrical circuit to be protected from ESD, said electrical circuit conducting a progressively increasing current in response to an applied ESD, and
a bypass circuit that is normally non-conductive but responds to said protected circuit current exceeding a threshold level by becoming conductive to provide a bypass path for said ESD to prevent it from damaging said electrical circuit, said bypass circuit comprising a pair of bipolar transistors of a first conductivity connected to be actuated by said electrical circuit's current exceeding said threshold level, and a pair of bipolar transistors of opposite conductivity and connected to be actuated by current flows through said first conductivity transistors.

An ESD protected differential circuit, comprising:

a pair of input terminals,
a reference voltage terminal,
an electrical circuit having a pair of input bipolar transistors whose bases are connected in circuit with respective ones of said input terminals to provide a differential input to the circuit,
a pair of bipolar bypass transistors of a first conductivity whose bases are connected to the bases of respective ones of the input transistors, and whose collector-emitter circuits are connected in series between said input terminals, and
a pair of bipolar bypass transistors of a second conductivity opposite to said first conductivity whose bases are connected to the series connection between said first conductivity transistors, and whose collector-emitter circuits are connected between said reference voltage terminal and respective ones of said input terminals.

2 more elements

Dependencies are inferred from the claim text.

ESD protection circuit for integrated circuits having a bipolar differential input

Life of this patent

ESD protection circuit for integrated circuits having a bipolar differential input

Life of this patent

Abstract

Claims17