Driver current control apparatus and methods

Abstract

Apparatus and methods disclosed herein implement steady-state and fast transient electronic current limiting through power transistors, including power transistors used as pass elements associated with general purpose drivers. Embodiments herein prevent excessive steady-state current flow through one or more driver pass elements and / or through load elements in series with the pass element(s) via a current sensing and driver preamplifier feedback loop. A transient over-current protection circuit includes a fast transient switch and a transient over-current control circuit. The transient over-current control circuit rectifies one or more transient voltage spikes to create a momentary direct current (DC) voltage power supply (MVS) to power a fast transient driver circuit and to trip the fast transient switch. The fast transient switch discharges a transient pass element input voltage (e.g., a gate voltage on a MOSFET power transistor in some embodiments) and terminates current flow through the pass element current channel.

Description

TECHNICAL FIELD[0001]Structures described herein relate to electronic circuits, including current-limiting circuits associated with power transistors and general purpose drivers.BACKGROUND INFORMATION[0002]FIGS. 1 and 2 are prior-art schematic diagrams of general purpose drivers 100 and 200 and example load circuits 110. General purpose configurable drivers provide regulated currents for applications such as light-emitting diodes (LEDs), “squibs” (small explosive devices) used in automobile air bag deployment systems, etc.[0003]FIG. 1 illustrates a “high side” configuration, so-called because the load circuit 110 is switched to the high side (e.g., to the drain 112 in this particular example) of the pass element 115. The pass element 115 is typically driven by a preamplifier (e.g., the preamplifier 120) and passes current to the load circuit 110. In an example automobile application, R(LOAD) 125 may represent one or more LEDs, an airbag squib, etc. as previously mentioned. L(WIRING)...

AI Technical Summary

Benefits of technology

The patent text describes a way to limit the amount of electric current that can flow through power transistors in an electronic circuit. This is done by using a current regulating preamplifier and a sense element that helps monitor and balance the current. This technology helps prevent damage to the circuit due to over-current conditions.

Problems solved by technology

Without transient voltage spike protection, simply connecting the car battery might cause squib firing and air bag deployment.

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