Current detection and limiting method and apparatus
AssigneeConexant Systems, Inc.
InventorsJames Bunde Villadsen Skov, Lorenzo Crespi, Ketan B. Patel
Life of this patent
Estimating the term…
Abstract
An apparatus for detecting and controlling current. A current detector for generating a first value that represents an amount of current being delivered to a device. A current limit circuit for generating a second value that represents a maximum permitted current level from a current source. A current controller for controlling the amount of current drawn by the device if the first value exceeds the second value.
Claims17
An apparatus for detecting and controlling current comprising:
- a current detector for generating a first value that represents an amount of current being delivered to a device;
- a current limit circuit for generating a second value that represents a maximum current level which may be drawn from a power supply source;
- a current controller for controlling the amount of current drawn by the device if the first value exceeds the second value;
- and
- a second current controller for disconnecting the device if the first value exceeds a third value that represents a short circuit condition;
- wherein the current limit circuit comprises:
- a resistor having a predetermined value;
- a first bias current source coupled to the resistor, the first bias current source providing
- a first predetermined current;
- a second bias current source coupled to the resistor, the second bias current source providing a second predetermined current;
- and
- a switch for disconnecting the second bias current source if the first value exceeds the second value.
An apparatus for detecting and controlling current comprising:
- a current detector for generating a first value that represents an amount of current being delivered to a device;
- a current limit circuit for generating a second value that represents a maximum current level which may be drawn from a power supply source, the current limit circuit comprising:
- a resistor having a predetermined value;
- a first bias current source coupled to the resistor, the first bias currentsource providing a first predetermined current;
- a second bias current source coupled to the resistor, the second bias current source providing a second predetermined current;
- a switch for disconnecting the second bias current source if the first value exceeds the second value;
- and
- circuitry for reconnecting the second bias current source if the first value is lower than a third value;
- a current controller for controlling the amount of current drawn by the device if the first value exceeds the second value, comprising a gain control for controlling a gain of a pre-amplifier;
- a second current controller for disconnecting the device if the first value exceeds a fourth value;
- and
- wherein the first value is generated by a voltage drop across a resistor that is in line with the current being delivered to the device.
A method for detecting and controlling current comprising:
- generating a first voltage from a sense resistor in line with a current being provided to a device;
- generating a second voltage from a reference resistor in line with a bias current source;
- generating a control signal to reduce the current being provided to the device if the first voltage is greater than the second voltage;
- reducing a bias current of the bias current source after generating the control signal;
- and
- increasing the bias current if the first voltage is less than a third voltage.
Dependencies are inferred from the claim text.