HD74HC279

HD74HC279 Quad. S–R Latches Description The latch is ideally suited for use as temporary stage for binary information processing and input/output units. When either S or R is low, output is dependent on R input. When both inputs are high, Output is stored before the indicated steady-state input conditions were established. And when both inputs are low, output is high, but this high level are uncontinuance, if either of input goes high. Features High Speed Operation: tpd (S to Q) = 10 ns typ (CL = 50 pF) 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: ICC (static) = 2 µA max (Ta = 25°C) Function Table Input S* H L H L H : L : Q0 : Notes: 2 Output R H H L L Q Q0 H L H*1 High level Low level The level of Q respectively, before the indicated steady-state input conditions were established. 1. It is unpredictable, if S or R goes High. 2. As to latches which has two S inputs. H: Both of S inputs are high. L: Either or both of S inputs are low. HD74HC279 Pin Arrangement 1R 1S1 1S2 1Q 2R 2S 2Q GND 1 2 3 4 5 6 7 8 16 15 14 13 12 11 10 9 VCC 4S 4R 4Q 3S2 3S1 3R 3Q (Top view) Logic Diagram (1/2) R S1 S2 Q R S Q 2 HD74HC279 DC Characteristics Ta = 25°C Item Input voltage Symbol VIH Ta = –40 to +85°C Max — — — 0.5 1.35 1.8 — — — — — 0.1 0.1 0.1 0.33 0.33 ±1.0 20 µA µA I OL = 4 mA I OL = 5.2 mA Vin = VCC or GND Vin = VCC or GND, Iout = 0 µA V I OH = –4 mA I OH = –5.2 mA...