National Semiconductor Corporation

Thomas Yang

Tawen Mei

Lawrence Herbert Zuckerman

Perry Tsao

Keiichi McGuire

Chenguang Gong

Ravichander Bairi

A master modem is configured to generate a carrier signal for transmission over a wired connection. A slave modem is configured to change an impedance of the wired connection to alter generation of the carrier signal by the master modem. The impedance of the wired connection is changed based on data to be provided by the slave modem. The master modem can demodulate its own carrier signal to obtain the data provided by the slave modem. The impedance of the wired connection could be changed by changing an impedance of a transformer winding or inductor of the slave modem, where the transformer winding or inductor is coupled to the wired connection. The impedance of the wired connection could also be changed by changing a reactance of a circuit coupled to the wired connection.

Distributed modem architectures for power line communication systems and other wired communication systems

A regulator regulates one or more light emitting diodes (LEDs) so as to control an average current through the LEDs. The regulator could include a transistor switch that can couple the LEDs to ground. The regulator could also include circuitry that controls the transistor switch. The circuitry could use a substantially constant reference voltage to regulate the average current through the one or more LEDs. The transistor switch could couple the one or more LEDs to ground through a resistor, and the circuitry could include an error amplifier that compares the reference voltage to a voltage across the resistor. The circuitry could also include a gate driver that can drive a gate of the transistor switch. The error amplifier could be disabled for a period of time when the transistor switch is non-conductive, and the circuitry could include logic for enabling and disabling the error amplifier.

Circuit and method for average-current regulation of light emitting diodes

A method for sensing current independently of variations in operating conditions is provided that includes generating a switch signal at a switching element. A reference signal is generated at a reference signal generator that is operable to track the switching element. A sense signal is generated based on the switch signal. An output current of the switching element is sensed based on a difference between the reference signal and the sense signal.

Method and system for sensing current independently of variations in operating conditions

A system and a method are disclosed for providing a temperature compensated under-voltage-lockout circuit that has a trip point voltage that is not sensitive to temperature variation. The under-voltage-lockout circuit of the invention comprises (1) an inverter circuit that is coupled to a supply voltage and (2) a temperature compensation circuit that is coupled to the supply voltage and to the inverter circuit. The temperature compensation circuit and the inverter circuit temperature compensate a trip point voltage of the inverter circuit by driving an input of the inverter circuit with a voltage that has a same temperature coefficient as the trip point voltage of the inverter circuit.

Growing community of inventors

Milpitas, CA, United States of America

Thomas Yang