Texas Instruments Corporation

Mahmoud M Yazdani

Clarence D Lewis

Brian T Deng

Khodor S Elnashar

Dinghui Richard Nie

Matthew J DiMarco

A power reduction system for a UART system having a controllable oscillator for producing free-running clock signals. A controlled clock synchronizer having an output terminal is coupled to the oscillator and responsive to both a first control signal thereto and application of the free-running clock signals thereto to provide synchronized pulses and is responsive to both a second control signal different from the first control signal thereto and application of the free-running clock signals thereto to cease production of the synchronized pulses at the output terminal. A UART core controls the oscillator and the clock synchronizer and is operated under control of clock signals from the clock synchronizer. The controllable oscillator includes an inverter having a feedback circuit thereacross including a switch responsive to the third control signal to cause the oscillator to cease oscillation. The synchronizer includes a bistable circuit responsive to the first and second control signals and a gate responsive to the bistable circuit and the clock signals for controlling the status of the synchronized pulses at the output terminal.

Power reduction for UART applications in standby mode

A method and apparatus for a circuit physically realizing a Universal Asynchronous Receive/Transmit (UART) circuit 31, 40 having an automatic flow control feature. A preferred embodiment includes a UART 31 provided with additional control circuitry 39, 34 for automatically pausing transfers from the transmit data circuitry 35, 32 in response to a transition at the CTS (Clear to Send) input, and further provided with control circuitry 39 for automatically asserting and deasserting a RTS (Ready to Send) output when a receiver data threshold is reached.

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Allen, TX, United States of America

Mahmoud M Yazdani