| 摘要 |
PURPOSE:To obtain a timer with PWM function in simple constitution by using a flip-flop which is reset and set by the reset and overflow signals of a counter respectively and transmits a PWM signal. CONSTITUTION:When the changeover signal of a supply terminal 15 is set at logic ''0'', a counter 2 is not reset any more since an AND gate 5 is kept closed although the timer output signal is set at logic ''1''. Thus the counter 2 counts the clock signals corresponding to a prescribed time T decided by the hardware and supplies an overflow signal as a set input S of a flip-flop 6. The digital value corresponding to the desired time t1 is set to a register 1 and therefore the count value of the counter 2 is coincident with the contents of the register 1 when the time t1 elapses after the counter has an overflow. Thus a timer output signal is supplied to a reset inout R of the flip-flop 6 in the form of logic ''1'' from a coincidence circuit 3. Then the PWM output signal is set at logic ''0''.
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