Central combined active ESD clamp

Patent metadata

Field	Value
Publication number	US-10367350-B2
Application number	US-201615199379-A
Country	US
Kind code	B2
Filing date	Jun 30, 2016
Priority date	Jun 30, 2016
Publication date	Jul 30, 2019
Grant date	Jul 30, 2019

Abstract

An electrostatic discharge clamp for groups of terminals having cascaded and different voltage classes, a plurality of discharge paths, and a multiple-input trigger circuit. In response to detecting a positive voltage event at any of the groups of terminals, the trigger circuitry can turn on an electronic switch causing current caused by the voltage event to flow through one or more of the discharge paths instead of through functional circuitry which could potentially be damaged by the current caused by the voltage event.

First claim

What is claimed is:

1. A circuit comprising:
a trigger circuit comprising a first input, a second input, an anode, a switched output, and a transistor,
wherein the anode is configured to be coupled to a reference voltage,
wherein the first input is configured to monitor a first highest voltage level provided at a first group of terminals, the first group of terminals configured to operate within a first voltage class,
wherein the second input is configured to monitor a second highest voltage level provided at a second group of terminals, the second group of terminals configured to operate within a second voltage class that is different from the first voltage class,
wherein a second maximum operating voltage for the second group of terminals is different than a first maximum operating voltage for the first group of terminals and wherein at least one of the first group of terminals or the second group of terminal comprises a plurality of terminals, and
wherein the transistor is configured to provide an output signal at the switched output when the first highest voltage level exceeds a first trigger threshold voltage and when the second highest voltage level exceeds a second trigger threshold voltage;

a single electronic switching device comprising a first node coupled to the switched output, a second node directly coupled to the second input, and a third node directly coupled to the anode, the electronic switching device configured to receive the output signal, and to switch on and to clamp a voltage level occurring at the first group of terminals and at the second group of terminals relative to the reference voltage; and
a forward-biased diode having an anode coupled to the first input of the trigger circuit and a cathode coupled to the second input of the trigger circuit, the forward-biased diode configured to conduct current through the forward-biased diode from the first input to the second input and through the single electronic switching device when the single electronic switching device is switched on.

2. The circuit of claim 1 , wherein the first input is coupled to the transistor, and a first stack of diodes, the first stack of diodes configured to have a first predetermined threshold voltage level set to the first trigger threshold voltage and configured to turn on the transistor when a voltage level received at the first input exceeds the first trigger threshold voltage.

3. The circuit of claim 2 , wherein the second input is coupled to a second stack of diodes, the second stack of diodes is coupled in series with the first stack of diodes, the second stack of diodes arranged to have a second predetermined threshold voltage level across the second stack of diodes to set the second trigger threshold voltage comprising a sum of the first predetermined threshold voltage level and the second predetermined threshold voltage level voltage, the second stack of diodes configured to turn on the transistor when a voltage level received at the second input exceeds the second trigger threshold voltage.

4. The circuit of claim 3 , wherein the second threshold voltage level is higher than the reference voltage provided at the anode and is higher than the first threshold voltage level.

5. The circuit of claim 3 , wherein a size of the single electronic switching device is 14000 μm 2 , and a size for any diodes in the first stack of diodes and the second stack of diodes is equal to or less than 500 μm 2 .

6. The circuit of claim 1 , wherein the first input of the trigger circuit is configured to be coupled to each terminal of the first group of terminals through a first set of forward-biased diodes, each of the diodes of the first set of forward biased diodes having an anode coupled to one and only one terminal of the first group of terminals and a cathode coupled to the first input of the trigger circuit; and
wherein the second input of the trigger circuit is configured to be coupled to each terminal of the second group of terminal through a second set of forward biased diodes, each of the diodes of the second set of forward biased diodes having an anode coupled to one and only one terminal of the second group of terminals and a cathode coupled to the second input of the trigger circuit.

7. The circuit of claim 1 , wherein the single electronic switching device is configured to, when switched on, provide a path circuitry to conduct current from the first group of terminals and from the second group of terminals through the semiconductor device to the reference voltage to redirect current away from one or more functional circuits coupled to either the first group of terminals or the second group of terminals.

8. The circuit of claim 1 , wherein the first group of terminals comprises a plurality of terminals having at least one of the plurality of terminals configured to provide a first supply voltage level that is higher than the reference voltage, and at least a second one of the plurality of terminals configured to operate at some times at an operating voltage level that is higher than the reference voltage and less than the first supply voltage level.

9. The circuit of claim 1 , wherein the second group of terminals comprises a plurality of terminals having at least one of the plurality of terminals configured to provide a second supply voltage level that is higher than the reference voltage and higher than a maximum operating voltage for the first voltage class, and at least a second one of the plurality of terminals configured to operate at some times at an operating voltage level that is higher than the reference voltage and less than the second supply voltage level.

10. A method of providing overvoltage protection for an electronic circuit comprising:
receiving at a first input of a trigger circuit a first highest voltage level provided by a first group of terminals, the first group of terminals operating in a first voltage class such that a transistor is switched on when a voltage at the first input is equal to or exceeds the first voltage class;
receiving at a second input of the trigger circuit a second highest voltage level provided by a second group of terminals, the second group of terminals operating in a second voltage class that is different from the first voltage class such that the transistor is switched on when a voltage at the second input is equal to or exceeds the second voltage class;
determining, with the transistor, if the first highest voltage level exceeds a first trigger threshold voltage, and generating an output signal configured to turn on a semiconductor device to activate a path circuitry coupling the first group of terminals to an anode to clamp the first highest voltage level relative to a reference voltage at the anode during a time when the first highest voltage level exceeds the first trigger threshold voltage, wherein the semiconductor device comprises a first node configured to receive the output signal, a second node directly coupled to the second input, and a third node directly coupled to the anode; and
determining, with the transistor, if the second highest voltage level exceeds a second trigger threshold voltage, and generating the output signal configured to turn on the semiconductor device to activate the path circuitry coupling the second group of terminals to the anode to clamp the second highest voltage level relative to the reference voltage during a time when the second highest voltage level exceeds the second trigger threshold voltage;
wherein at least one of the first group of terminals or the second group of terminal includes a plurality of terminals, and
wherein an anode of a forward-biased diode is coupled to the first input of the trigger circuit, wherein a cathode of

Assignees

• Infineon Technologies Ag

Inventors

• Glaser Ulrich
• Panaite Dragos

Classifications

• H02H9/046 Primary

  responsive to excess voltage appearing at terminals of integrated circuits · CPC title