US 2015/0318691 A2 · 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.

Claims20

Dependent claims

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.

1 more element

A fast-transient current-limiting apparatus, comprising:

a fast transient switching element, a first terminal of a current channel of the fast transient switching element communicatively coupled to a ground rail and a control input of the fast transient switching element communicatively coupled to a transient over-current control circuit;
a switching diode, a cathode of the switching diode coupled to a second terminal of the current channel of the fast transient switching element and an anode of the switching diode coupled to a gate of a power transistor with a high Miller capacitance and subject to at least one transient voltage spike at a terminal of a current channel of the power transistor;
a fast transient driver communicatively coupled to an input terminal of the fast transient switching element via a control signal (CNTRL) output of the fast transient driver to cause the fast transient switching element to conduct upon an occurrence of the transient voltage spikes during a time when the power transistor is not subject to intentionally active use;
a momentary voltage supply (MVS) rail communicatively coupled to the fast transient driver to power the fast transient driver and to place the CNTRL output in an active state when the power transistor is not subject to intentionally active use;
an MVS voltage control element communicatively coupled between the MVS rail and the ground rail to establish a maximum voltage of the MVS rail;
an MVS disable switch communicatively coupled between the MVS rail and the ground rail to disable the fast transient switch during a period when the power transistor is not subject to intentionally active use;
and
a charge accumulation circuit coupled between the terminal of the current channel of the power transistor subject to the transient voltage spikes and the MVS rail to rectify the transient voltage spikes occurring at the terminal of the current channel of the power transistor in order to create an MVS voltage.

5 more elements

Dependencies are inferred from the claim text.

Driver current control apparatus and methods

Life of this patent

Driver current control apparatus and methods

Life of this patent

Abstract

Claims20