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ESD/EOS Protection Device with Line-Switch-Off Function

IP.com Disclosure Number: IPCOM000239815D
Publication Date: 2014-Dec-03
Document File: 7 page(s) / 342K

Publishing Venue

The IP.com Prior Art Database

Abstract

The ESD/EOS protection device with line-switch-off function arrangement consists of the combination of a protection device that drains excessive current to ground, a current sensor that produces a signal when the protection device carries large currents and a pass-gate that disconnects the signal path whenever the current sensor gives a signal the signal from the current sensor

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ESD/EOS Protection Device with Line-Switch-Off Function

Country of Origin: Germany

Abstract

The ESD/EOS protection device with line-switch-off function arrangement consists of the combination of a protection device that drains excessive current to ground, a current sensor that produces a signal when the protection device carries large currents and a pass-gate that disconnects the signal path whenever the current sensor gives a signal the signal from the current sensor

Current art

ESD/EOS protection devices drain excessive current to ground (or another rail). The stress current is divided between the external protection device and the internal protection of the IC: The risk that the internal protection of the IC gets damaged is still exiting especially for longer stress pulses.Overvoltage protection devices limit the voltage seen by an IC by disconnecting the IC from the external contact when the voltage at the external contact s larger than a specific value.

Integrated circuits that have connections to external contacts usually are protected by external components placed on the board between the external contacts and the integrated circuit. These protection devices drain ESD/EOS caused stress currents to ground and clamp the voltage on the line to an acceptable level. Nonetheless the internal ESD protection circuit of the IC will still be stressed and will have to drain current to ground - the total stress current is divided between the external protection device and the internal protection of the IC: Furthermore the internal protection circuits of ICs are usually optimized for short pulses like Human Body Model (HBM); they tend to be destroyed if the pulses are much longer as can be the case with surge pulses. As long as the stress current is shared between the external protection and the internal protection the risk remains that the IC will be damaged

Solution

The signal path will be disconnected when a stress pulse is drained via the protection device and it will be re-opened when the stress pulse has ended. In that way the internal protection of the IC will not be stressed for the whole timespan of the stress.

The arrangement consists of the combination of a protection device that drains excessive current to ground, a current sensor that produces a signal when the

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protection device carries a large enough current and a pass-gate that disconnects the signal path whenever the current sensor gives a signal.

 "external" denotes an external contact on e.g. a board
 "internal" denotes an input pin of an IC
 "pass gate" is similar to a switch the disconnects the signal line when a trigger pulse is received from the current sensor

 "protection and trigger for pass-gate" this includes a structure that can drain excessive current from the signal line to the ground line (similar to a diode), further a current-sensor that detects whether current passes through the protection structure and further a 'logic' that pr...