Revised March 2000 DM74LS279 Quad S-R Latch General Description The DM74LS279 consists of four individual and independent Set-Reset Latches with active low inputs. Two of the four latches have an additional S input ANDed with the primary S input. A LOW on any S input while the R input is HIGH will be stored in the latch and appear on the corresponding Q output as a HIGH. A LOW on the R input while the S input is HIGH will clear the Q output to a LOW. Simultaneous transition of the R and S inputs from LOW-toHIGH will cause the Q output to be indeterminate. Both inputs are voltage level triggered and are not affected by transition time of the input data. Ordering Code: Order Number Package Number Package Description DM74LS279M M16A 16-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-012, 0.150 Narrow DM74LS279N N16E 16-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300 Wide Devices also available in Tape and Reel. Specify by appending the suffix letter “X” to the ordering code. Connection Diagram Function Table Inputs Output S (Note 1) R Q L L H (Note 2) H L H H L L H H Q0 H = HIGH Level L = LOW Level Q0 = The Level of Q before the indicated input conditions were established. Note 1: For latches with double S inputs: H = both S inputs HIGH L = one or both S inputs LOW Note 2: This output level is pseudo stable; that is, it may not persist when the S and R inputs return to their inactive (HIGH) level. © 2000 Fairchild Semiconductor Corporation DS006420 www.fairchildsemi.com DM74LS279 Quad S-R Latch August 1986 DM74LS279 Absolute Maximum Ratings(Note 3) Supply Voltage Note 3: The “Absolute Maximum Ratings” are those values beyond which the safety of the device cannot be guaranteed. The device should not be operated at these limits. The parametric values defined in the Electrical Characteristics tables are not guaranteed at the absolute maximum ratings. The “Recommended Operating Conditions” table will define the conditions for actual device operation. 7V Input Voltage 7V 0°C to +70°C Operating Free Air Temperature Range −65°C to +150°C Storage Temperature Range Recommended Operating Conditions Symbol Parameter Min Nom Max 4.75 5 5.25 Units VCC Supply Voltage VIH HIGH Level Input Voltage V VIL LOW Level Input Voltage 0.8 V IOH HIGH Level Output Current −0.4 mA IOL LOW Level Output Current 8 mA TA Free Air Operating Temperature 70 °C 2 V 0 Electrical Characteristics over recommended operating free air temperature range (unless otherwise noted) Symbol Parameter Conditions VI Input Clamp Voltage VCC = Min, II = −18 mA VOH HIGH Level VCC = Min, IOH = Max Output Voltage VIL = Max, VIH = Min VOL LOW Level VCC = Min, IOL = Max Output Voltage VIL = Max, VIH = Min Min Typ (Note 4) 2.7 IOL = 4 mA, VCC = Min Max Units −1.5 V 3.5 V 0.35 0.5 0.25 0.4 V II Input Current @ Max Input Voltage VCC = Max, VI = 7V 0.1 IIH HIGH Level Input Current VCC = Max, VI = 2.7V 20 µA IIL LOW Level Input Current VCC = Max, VI = 0.4V −0.4 mA IOS Short Circuit Output Current VCC = Max (Note 5) ICC Supply Current VCC = Max (Note 6) −20 mA −100 mA 7 mA 3.8 Note 4: All typicals are at VCC = 5V, TA = 25°C. Note 5: Not more than one output should be shorted at a time, and the duration should not exceed one second. Note 6: ICC is measured with all R inputs grounded, all S inputs at 4.5V and all outputs OPEN. Switching Characteristics at VCC = 5V and TA = 25°C RL = 2 kΩ From (Input) Symbol Parameter CL = 15 pF To (Output) Min tPLH Propagation Delay Time LOW-to-HIGH Level Output tPHL Propagation Delay Time HIGH-to-LOW Level Output tPHL Propagation Delay Time HIGH-to-LOW Level Output www.fairchildsemi.com Max CL = 50 pF Min Units Max S to Q 22 25 ns S to Q 15 23 ns R to Q 27 33 ns 2 DM74LS279 Physical Dimensions inches (millimeters) unless otherwise noted 16-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-012, 0.150 Narrow Package Number M16A 3 www.fairchildsemi.com DM74LS279 Quad S-R Latch Physical Dimensions inches (millimeters) unless otherwise noted (Continued) 16-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300 Wide Package Number N16E Fairchild does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and Fairchild reserves the right at any time without notice to change said circuitry and specifications. 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