DRIVER CURRENT CONTROL APPARATUS AND METHODS

摘要

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.

主权项

1. A driver and electronic current-limiting apparatus, comprising:
a current regulating preamplifier to establish a desired level of current through a load and to detect a steady-state over-current condition; a pass element with a current channel coupled in series with the load to receive a drive signal from the preamplifier at an input terminal (common gate node “CGN”) of the pass element and to control the desired level of current via the drive signal; and a fast transient switch associated with a transient over-current protection circuit, the fast transient switch communicatively coupled between the CGN and a ground rail to discharge an electrical charge accumulated at the input terminal of the pass element as a consequence of at least one transient voltage spike at a higher-voltage terminal of the pass element current channel (“DR terminal”), the electrical charge resulting in a bias voltage on the input terminal of the pass element, the bias voltage capable of causing excessive conduction through the current channel of the pass element.