The HEF4047BT is a gatable Monostable/Astable Multivibrator incorporating logic techniques to permit positive or negative edge-triggered monostable multivibrator action with retriggering and external counting options. Inputs include +TRIGGER, -TRIGGER, ASTABLE, ASTABLE\, RETRIGGER and MR (master reset). Buffered outputs are O, O\ and oscillator output. In all modes of operation an external capacitor (Ct) must be connected between CTC and RCTC and an external resistor (Rt) must be connected between RTC and RCTC. A high level on the ASTABLE input enables astable operation. The period of the square wave at O and O\ outputs is a function of the external components employed. True input pulses on the ASTABLE or complement pulses on the ASTABLE\ input, allows the circuit to be used as a gatable multivibrator. The oscillator output period is half of the O output in the astable mode. However, a 50% duty factor is not guaranteed at this output.
Positive- or negative-edge triggering
Output pulse width independent of trigger pulse duration
Retriggerable option for pulse-width expansion
Long pulse width possible using small RC components with external counter provision
