54LS279/DM54LS279/DM74LS279 Quad S-R Latches General Description The 'LS279 consists of four individual and independent SetReset Latches with active low inputs. Two of the four latches have an additonal 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 transistion of the R and S inputs from low to high 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. Features Y Alternate military/aerospace device (54LS279) is available. Contact a National Semiconductor Sales Office/ Distributor for specifications. Connection Diagram Dual-In-Line Package TL/F/6420 - 1 Order Number 54LS279DMQB, 54LS279FMQB, 54LS279LMQB, DM54LS279J, DM74LS279M or DM74LS279N See NS Package Number E20A, J16A, M16A, N16E or W16A Function Table Inputs Output S(1) R Q L L H H L H L H H* H L Q0 H e High Level L e Low Level Q0 e The Level of Q before the indicated input conditions were established. *This output level is pseudo stable; that is, it may not persist when the S and R inputs return to their inactive (high) level. Note 1: For latches with double S inputs: H e both S inputs high L e one or both S inputs low C1995 National Semiconductor Corporation TL/F/6420 RRD-B30M105/Printed in U. S. A. 54LS279/DM54LS279/DM74LS279 Quad S-R Latches May 1989 Absolute Maximum Ratings (Note) Note: 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'' table are not guaranteed at the absolute maximum ratings. The ``Recommended Operating Conditions'' table will define the conditions for actual device operation. If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/Distributors for availability and specifications. Supply Voltage 7V Input Voltage 7V Operating Free Air Temperature Range b 55 C to a 125 C DM54LS and 54LS DM74LS 0 C to a 70 C Storage Temperature Range b 65 C to a 150 C Recommended Operating Conditions Symbol DM54LS279 Parameter VCC Supply Voltage VIH High Level Input Voltage VIL Low Level Input Voltage IOH High Level Output Current IOL Low Level Output Current TA Free Air Operating Temperature DM74LS279 Units Min Nom Max Min Nom Max 4.5 5 5.5 4.75 5 5.25 2 2 V 0.7 0.8 V b 0.4 b 0.4 mA 8 mA 70 C 4 b 55 V 125 0 Electrical Characteristics over recommended operating free air temperature range (unless otherwise noted) Symbol Parameter Conditions Min Typ (Note 1) Max Units b 1.5 V VI Input Clamp Voltage VCC e Min, II e b18 mA VOH High Level Output Voltage VCC e Min, IOH e Max DM54 2.5 3.5 VIL e Max, VIH e Min DM74 2.7 3.5 VCC e Min, IOL e Max VIL e Max, VIH e Min DM54 0.25 0.4 DM74 0.35 0.5 IOL e 4 mA, VCC e Min DM74 0.25 0.4 VOL Low Level Output Voltage V V II Input Current @ Max Input Voltage VCC e Max, VI e 7V 0.1 mA IIH High Level Input Current VCC e Max, VI e 2.7V 20 mA IIL Low Level Input Current VCC e Max, VI e 0.4V b 0.4 mA IOS Short Circuit Output Current VCC e Max (Note 2) Supply Current VCC e Max (Note 3) ICC DM54 b 20 b 100 DM74 b 20 b 100 3.8 Note 1: All typicals are at VCC e 5V, TA e 25 C. Note 2: Not more than one output should be shorted at a time, and the duration should not exceed one second. Note 3: ICC is measured with all R inputs grounded, all S inputs at 4.5V and all outputs open. 2 7 mA mA Switching Characteristics at VCC e 5V and TA e 25 C (See Section 1 for Test Waveforms and Output Load) Symbol Parameter RL e 2 kX From (Input) To (Output) CL e 15 pF Min Max CL e 50 pF Min Units Max tPLH Propagation Delay Time Low to High Level Output S to Q 22 25 ns tPHL Propagation Delay Time High to Low Level Output S to Q 15 23 ns tPHL Propagation Delay Time High to Low Level Output R to Q 27 33 ns 3 Physical Dimensions inches (millimeters) Ceramic Leadless Chip Carrier Package (E) Order Number 54LS279LMQB NS Package Number E20A 16-Lead Ceramic Dual-In-Line Package (J) Order Number 54LS279DMQB or DM54LS279J NS Package Number J16A 4 Physical Dimensions inches (millimeters) (Continued) 16-Lead Small Outline Molded Package (M) Order Number DM74LS279M NS Package Number M16A 16-Lead Molded Dual-In-Line Package (N) Order Number DM74LS279N NS Package Number N16E 5 54LS279/DM54LS279/DM74LS279 Quad S-R Latches Physical Dimensions inches (millimeters) (Continued) 16-Lead Ceramic Flat Package (W) Order Number 54LS279FMQB or DM54LS279W NS Package Number W16A LIFE SUPPORT POLICY NATIONAL'S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT OF NATIONAL SEMICONDUCTOR CORPORATION. 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