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| DM74LS279 Quad S-R Latch August 1986 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 DM74LS279M DM74LS279N Package Number M16A N16E Package Description 16-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-012, 0.150 Narrow 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 S (Note 1) L L H H R L H L H Output Q H (Note 2) H L 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. (c) 2000 Fairchild Semiconductor Corporation DS006420 www.fairchildsemi.com DM74LS279 Absolute Maximum Ratings(Note 3) Supply Voltage Input Voltage Operating Free Air Temperature Range Storage Temperature Range 7V 7V 0C to +70C -65C to +150C 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. Recommended Operating Conditions Symbol VCC VIH VIL IOH IOL TA Supply Voltage HIGH Level Input Voltage LOW Level Input Voltage HIGH Level Output Current LOW Level Output Current Free Air Operating Temperature 0 Parameter Min 4.75 2 0.8 -0.4 8 70 Nom 5 Max 5.25 Units V V V mA mA C Electrical Characteristics over recommended operating free air temperature range (unless otherwise noted) Symbol VI VOH VOL Parameter Input Clamp Voltage HIGH Level Output Voltage LOW Level Output Voltage II IIH IIL IOS ICC Input Current @ Max Input Voltage HIGH Level Input Current LOW Level Input Current Short Circuit Output Current Supply Current Conditions VCC = Min, II = -18 mA VCC = Min, IOH = Max VIL = Max, VIH = Min VCC = Min, IOL = Max VIL = Max, VIH = Min IOL = 4 mA, VCC = Min VCC = Max, VI = 7V VCC = Max, VI = 2.7V VCC = Max, VI = 0.4V VCC = Max (Note 5) VCC = Max (Note 6) -20 3.8 2.7 3.5 0.35 0.25 0.5 0.4 0.1 20 -0.4 -100 7 mA A mA mA mA Min Typ (Note 4) Max -1.5 Units V V V Note 4: All typicals are at VCC = 5V, TA = 25C. 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 = 25C From (Input) Symbol Parameter To (Output) CL = 15 pF Min tPLH tPHL tPHL Propagation Delay Time LOW-to-HIGH Level Output Propagation Delay Time HIGH-to-LOW Level Output Propagation Delay Time HIGH-to-LOW Level Output S to Q Max 22 RL = 2 k CL = 50 pF Min Max 25 ns Units S to Q 15 23 ns R to Q 27 33 ns www.fairchildsemi.com 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. LIFE SUPPORT POLICY FAIRCHILD'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 FAIRCHILD SEMICONDUCTOR CORPORATION. As used herein: 1. Life support devices or systems are devices or systems which, (a) are intended for surgical implant into the body, or (b) support or sustain life, and (c) whose failure to perform when properly used in accordance with instructions for use provided in the labeling, can be reasonably expected to result in a significant injury to the user. www.fairchildsemi.com 4 2. A critical component in any component of a life support device or system whose failure to perform can be reasonably expected to cause the failure of the life support device or system, or to affect its safety or effectiveness. www.fairchildsemi.com |
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