Active detection and protection of sensitive circuits against transient electrical stress events

摘要

Apparatus and methods for active detection, timing, and protection related to transient electrical events are disclosed. A detection circuit can generate a first activation signal in response to a transient electrical stress event across a first node and a second node. A blocking circuit is configured to bias the base of a first driver bipolar transistor to slow down discharge of accumulated base charge of a first driver bipolar transistor, which permits the first driver bipolar transistor to remain activated for a longer period of time than had the base of the first driver bipolar transistor been biased to the same voltage as the emitter of the first bipolar transistor. Shut-off circuitry can be included in some embodiments to prevent a discharge circuit from activating during normal operating conditions.

主权项

1. An apparatus comprising:
a detection circuit configured to generate a first activation signal in response to a transient electrical stress event at a first node; a driver circuit operatively coupled to the detection circuit, the driver circuit including a first driver bipolar transistor having a base, an emitter, and a collector, wherein the first driver bipolar transistor is configured to activate, saturate, and accumulate base charge in response to the first activation signal, and wherein the driver circuit is configured to generate a second activation signal at least while the first driver bipolar transistor is activated; a discharge circuit operatively coupled to the driver circuit and configured to activate a low impedance path between the first node and a second node at least while the driver circuit generates the second activation signal; and a first blocking circuit operatively coupled to the driver circuit and configured to be activated by the first activation signal, wherein the first blocking circuit is configured to bias the base of the first driver bipolar transistor to a different voltage than the emitter of the first driver bipolar transistor for a period of time after the first activation signal has ceased to slow down discharge of accumulated base charge of the first driver bipolar transistor such that the first driver bipolar transistor remains activated for a longer period of time than had the base of the first driver bipolar transistor been biased to the same voltage as the emitter of the first bipolar transistor.