Revised March 2000 DM74LS298 Quad 2-Port Register Multiplexer with Storage General Description Features The DM74LS298 is a quad 2-port register. It is the logical equivalent of a quad 2-input multiplexer followed by a quad 4-bit edge-triggered register. A Common Select input selects between two 4-bit input ports (data sources). The selected data is transferred to the output register synchronous with the HIGH-to-LOW transition of the Clock input. ■ Select from two data sources ■ Fully edge-triggered operation ■ Typical power dissipation of 65 mW Ordering Code: Order Number Package Number DM74LS298N N16E Package Description 16-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300 Wide Connection Diagram Logic Symbol VCC = Pin 16 GND = Pin 8 Truth Table Pin Descriptions Pin Names Inputs Description Output S Common Select Inputs S I0x I1x CP Clock Pulse Input (Active Falling Edge) l l X Qx L I0a, I0d Source 0 Data Inputs l h X H I1a, I1d Source 1 Data Inputs h X l L Qa, Qd Flip-Flip Outputs h X h H l = LOW Voltage Level one setup time prior to the HIGH-to-LOW clock transition. h = HIGH Voltage Level one setup time prior to the HIGH-to-LOW clock transition. H = HIGH Voltage Level L = LOW Voltage Level X = Immaterial © 2000 Fairchild Semiconductor Corporation DS009826 www.fairchildsemi.com DM74LS298 Quad 2-Port Register Multiplexer with Storage October 1988 DM74LS298 Functional Description This device is a high speed quad 2-port register. It selects four bits of data from two sources (ports) under the control of a Common Select input (S). The selected data is transferred to the 4-bit output register synchronous with the HIGH-to-LOW transition of the Clock input (CP). The 4-bit output register is fully edge-triggered. The Data inputs (I nx) and Select input (S) need be stable only one setup time prior to the HIGH-to-LOW transition of the clock for predictable operation. Logic Diagram www.fairchildsemi.com 2 Supply Voltage Note 1: 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 8 mA 70 °C 2 IOL LOW Level Output Current TA Free Air Operating Temperature 0 tS (H) Setup Time HIGH or LOW 25 tS (L) S to CP 25 tH (H) Hold Time HIGH or LOW 0 tH (L) S to CP 0 tS (H) Setup Time HIGH or LOW 15 tS (L) I0x or I1x to CP 15 tH (H) Hold Time HIGH or LOW 5.0 tH (L) I0x or I1x to CP 5.0 tW (H) CP Pulse Width HIGH or LOW 20 tW (L) V ns ns ns ns ns 20 Electrical Characteristics over recommended operating free air temperature range (unless otherwise noted) Symbol Parameter Conditions Min Typ (Note 2) Max VI Input Clamp Voltage VCC = Min, II = −18 mA VOH HIGH Level Output Voltage VCC = Min, IOH = Max, VIL = Max VOL LOW Level Output Voltage VCC = Min, IOL = Max, VIH = Min 0.35 0.5 IOL = 4 mA, VCC = Min 0.25 0.4 II Input Current @ Max Input Voltage VCC = Max, VI = 7V, VI = 10V Units −1.5 2.7 V 3.4 V V 0.1 mA 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 3) −100 mA ICC Supply Current VCC = Max, I0n, I1n, 21 mA S = GND, CP = Note 2: All typicals are at VCC = 5V, TA = 25°C. −20 Note 3: Not more than one output should be shorted at a time, and the duration should not exceed one second. Switching Characteristics at VCC = +5V and TA = +25°C Symbol tPLH RL = 2 kΩ, CL = 15 pF Parameter Min Max Units Propagation Delay Time LOW-to-HIGH Level Output 25 ns 25 ns CP to Qn tPHL Propagation Delay Time HIGH-to-LOW Level Output CP to Qn 3 www.fairchildsemi.com DM74LS298 Absolute Maximum Ratings(Note 1) DM74LS298 Quad 2-Port Register Multiplexer with Storage Physical Dimensions inches (millimeters) unless otherwise noted 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: 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. 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 www.fairchildsemi.com 4