Description
CD4047 consists of a gatable astable multivibrator with logic techniques incorporated to permit positive or negative edge-triggered monostable multivibrator action with retriggering and external counting options. Inputs include +TRIGGER, -TRIGGER, ASTABLE, ASTABLE/, RETRIGGER, and EXTERNAL RESET. Buffered outputs are Q/, Q and OSCILLATOR. In all modes of operation, and external capacitor must be connected between C-Timing and RC-Common terminal, and an resistor must be connected between the R-Timing and RC-Common terminals. Astable operation enabled by a high level on the STABLE input or a low level on the ASTABLE/ input, or both. The period of the square wave at the Q and Q/ Outputs in this mode off operation is a function of the external components employed. “True” input pulses on the ASTABLE input or “Complement” pulses on the ASTABLE/ input allow the circuit to be used as a gatable multivibrator. The OSCILLATOR output period will be half of the Q terminal output in the astable mode. The CD4047B triggers in the monostable mode when a positive-going edge occurs on the +TRIGGER-input while the -TRIGGER is held low. INput pulses may be of any duration relative to the output pulse. If retrigger capability is desired, the RETRIGGER input is pulsed. The retriggerable mode of operation is limited to positive-going edge. The CD4047B will retrigger as long as the RETRIGGER-input is high, with or without transitions. An external countdown option can be implemented by coupling “Q”; to an external “N” counter and resetting the counter with the trigger pulse. The counter output pulse is fed back to the ASTABLE/ input and has a duration equal to N times the period of the multivibrator. A high on the EXTERNAL RESET input assures no output pulse during an “ON”; power condition. This input can also be activated to terminate the output pulse at any time.
