DUTY RATIO DECIDING CIRCUIT AND METHOD FOR DECIDING DUTY RATO

摘要

PROBLEM TO BE SOLVED: To decide a duty ratio with a simple circuit configuration. ;SOLUTION: An up-down counter 2 starts to up and down count in response to a rise detection signal and a fall detection signal of a pulse from an edge detector 1. The detector 1 outputs a preset signal for designating an input of a start value of a count to the counter 2 immediately before the detector 1 outputs the rise detection signal. A CPU 5 sets a start value of a count to a register 6 so that a counted value becomes '0' at the time of ending one period of the pulse of a reference duty ratio. The counter 2 inputs a start value from the register 6 in response to a preset signal from the detector 1. An up- down counter status flag register 3 outputs '1' when the counted value is minus and outputs '0' when the counted value is plus.;COPYRIGHT: (C)2000,JPO