Power reduction for UART applications in standby mode

摘要

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.