Current limiting

About: Current limiting is a research topic. Over the lifetime, 12827 publications have been published within this topic receiving 92577 citations. The topic is also known as: OCP & over-current protection.

Thermal cautery system

Abstract: A thermal cautery system having an endoscopically deliverable probe connected to a power supply and display unit. The power supply and display unit, when triggered by a footswitch, energizes a voltage regulator having a current limited output that supplies power to the probe. The current limiting function of the voltage regulator is disabled for a predetermined period that power is initially applied to said probe to minimize the heating time of said probe. The current through said probe is sensed and used to increase the voltage at the output of the voltage regulator as the current increases to compensate for the voltage drop in the conductors connecting the probe to the power supply. A manually selected portion of the sensed current through the probe is also integrated and used to terminate the flow of current through the probe when the integral of the current with respect to time has reached a predetermined value. A tone generator provides an audible indication when power is being applied to the probe and for a predetermined period thereafter to allow the probe to cool before the absence of the tone signals the removal of the probe from tissue being coagulated. The probe is heated by current flowing through an internal diode having a predetermined breakdown voltage at a predetermined temperature. The temperature of the probe is self-regulated by applying a voltage to the probe that is substantially equal to said predetermined voltage so that the current through the probe is reduced at said predetermined temperature.

Current saturation mechanisms in carbon nanotube field emitters

Abstract: Recent studies have shown a current limiting effect in the field emission behavior of carbon nanotubes. In this letter, we demonstrate that an individual nanotube exhibits current saturation above 100 nA of emission current, and we show that this current saturation is a direct result of an adsorbate-enhanced field emission mechanism. Current saturation results from the displacement of adsorbates from configurations of tunneling enhancement as electric field and current are increased. Saturation is concurrent with rapid fluctuations in emission current and distinctive changes in the field emission patterns. At high fields, the adsorbate states are completely removed from the nanotube. A single, clean single-walled nanotube shows no evidence of current saturation for emission currents reaching 2 μA.

Class AB H-bridge using current sensing MOSFETs

Abstract: An apparatus and method for supplying bi-directional load current to a load device. Four current sensing metal oxide semiconductor field effect transistors are operably configured to form an H-bridge with the load device, each transistor having separately insulated gate, source and drain and sense terminals with a source to drain conductivity determined in relation to a voltage applied to the gate terminal and a sense current from the sense terminal determined in relation to a magnitude of source to drain current. Drive voltages are applied to the gate terminals of alternating pairs of the transistors to apply the load current to the load device. The sense currents are used to provide adaptive, closed-loop clamping of the drive voltages at levels sufficient to maintain the non-load current conducting transistors in a quiescent state.

Current-limiting battery usage within a corded electronic device

Abstract: This disclosure describes techniques for operating a corded electronic device in which a battery and a power control unit manage power draw from an external power source electrically coupled to the corded electronic device using a physical cord, such as a universal serial bus (USB) cable. The power control unit automatically supplements an electrical current continuously drawn by the corded electronic device from the external power source with an electrical current from the battery, when needed. Moreover, the power control unit operates to limit the current drawn from the external power source and the physical cord so as to ensure the current does not exceed any limitations or requirements associated with the external power source or the physical cord.

Apparatus and method for current control in H-Bridge load drivers

Abstract: An electronic current control circuit is provided. This electronic circuit comprises a power-supply, an H-Bridge module connected to a load, and a current sensor connected between the H-Bridge module and the power-supply and adapted to sense load current characteristics. A computerized controller is connected to the current sensor and the H-Bridge module, includes at least a module for operating load current analysis algorithm for analyzing the load current characteristics to determine current control parameters that provide over-current protection and load current control. A load current control module controls the H-Bridge module based upon the current control parameters.