74221

HD74HC221 Dual Monostable Multivibrators (with Schmitt Trigger Input) Description Each multivibrator features both a negative, A, and a positive, B, transition triggered input, either of which can be used as an inhibit. Also included is a clear inpt that when taken low resets the one shot. The HD74HC221 can be triggered on the positive transition of teh clear while A is held low and B is held high. This device is a non-retriggerable, and therefore cannot be retriggered until the output pulse times out. The output pulse equation is simply: tW = 0.7·(Rext)·(Cext) Features High Speed Operation High Output Current: Fanout of 10 LSTTL Loads Wide Operating Voltage: VCC = 2 to 6 V Low Input Current: 1 µA max Low Quiescent Supply Current Function Table Inputs Clear L X X H H L A X H X L H H B X X L Outputs Q L L L Q H H H HD74HC221 Pin Arrangement 1A 1B CLR1 1Q 2Q Cext 2 2 Rext/ Cext GND 1 2 3 4 5 Q CLR Q Q 16 15 14 13 12 11 10 9 (Top view) VCC 1 Rext/ Cext 1 Cext 1Q 2Q 2CLR 2B 2A Q CLR 6 7 8 Logic Diagram VCC Rext Cext Cext Rext /Cext A B Q Clear Q Q Clear 2 HD74HC221 DC Characteristics Sym- VCC Ta = 25°C Item Input voltage bol VIH Ta = –40 to +85°C (V) Min Typ Max Min Max Unit Test Conditions 2.0 1.5 — — — — 0.5 1.5 — V 4.5 3.15 — 6.0 4.2 VIL 2.0 — 4.5 — 6.0 — Output voltage VOH 2.0 1.9 4.5 4.4 6.0 5.9 — — — — 2.0 4.5 6.0 3.15 — 4.2 — — 0.5 1.35 1.8 — — — I OH = –4 mA I OH = –5.2 mA V Vin = VIH or VIL I OL = 20 µA V Vin = VIH or VIL I OH = –20 µA V 1...