DM54LS461/DM74LS461 Octal Counter General Description The LS461 is an 8-bit synchronous counter with parallel load, clear, and hold capability. Two function select inputs (I0, I1) provide one of four operations which occur synchronously on the rising edge of the clock (CK). The LOAD operation loads the inputs (D7 – D0) into the output register (Q7 – Q0). The CLEAR operation resets the output register to all LOWs. The HOLD operation holds the previous value regardless of clock transitions. The INCREMENT operation adds one to the output register when the carry-in input is TRUE (CI e LOW), otherwise the operation is a HOLD. The carry-out (CO) is TRUE (CO e LOW) when the output register (Q7 – Q0) is all HIGHs, otherwise FALSE (CO e HIGH). The output register (Q7 – Q0) is enabled when OE is LOW, and disabled (HI-Z) when OE is HIGH. The output drivers will sink the 24 mA required for many bus interface standards. Two or more LS461 octal counters may be cascaded to provide larger counters. The operation codes were chosen such that when I1 is HIGH, I0 may be used to select between LOAD and INCREMENT as in a program counter (JUMP/INCREMENT). Connection Diagram Standard Test Load Features/Benefits Y Y Y Y Y Y Y Octal counter for microprogram-counter, DMA controller and general purpose counting applications 8 bits match byte boundaries Bus-structured pinout 24-pin Skinny Dip saves space TRI-STATEÉ outputs drive bus lines Low current PNP inputs reduce loading Expandable in 8-bit increments Top View TL/L/8334 – 2 TL/L/8334 – 1 Order Number DM54LS461J, DM74LS461J or DM74LS461N See NS Package Number J24F or N24C Function Table OE CK I1 I0 CI D7 – D0 Q7 – Q0 Operation H L L L L L X X L L H H H X L H L H H X X X X H L X X X D X X Z L Q D Q Q plus 1 HI-Z CLEAR HOLD LOAD HOLD INCREMENT u u u u u TRI-STATEÉ is a registered trademark of National Semiconductor Corp. C1995 National Semiconductor Corporation TL/L/8334 RRD-B30M115/Printed in U. S. A. DM54LS461/DM74LS461 Octal Counter July 1989 Absolute Maximum Ratings Off-State Output Voltage If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/Distributors for availability and specifications. Supply Voltage VCC 5.5V Storage Temperature b 65§ C to a 150§ C 7V Input Voltage 5.5V Operating Conditions Symbol Military Parameter Min Typ 4.5 5 VCC Supply Voltage TA Operating Free-Air Temperature tW Width of Clock tSU Set Up Time 60 th Hold Time 0 Commercial b 55 Units Max Min Typ Max 5.5 4.75 5 5.25 V 125* 0 75 §C Low 40 35 High 30 25 ns 50 b 15 ns 0 b 15 *Case Temperature Electrical Characteristics Over Operating Conditions Symbol Parameter Test Conditions Min Typ ² Max Low-Level Input Voltage VIH High-Level Input Voltage VIC Input Clamp Voltage VCC e MIN II eb18 mA b 1.5 V IIL Low-Level Input Current VCC e MAX VI e 0.4V b 0.25 mA IIH High-Level Input Current VCC e MAX VI e 2.4V 25 mA II Maximum Input Current VCC e MAX VI e 5.5V 1 mA VOL Low-Level Output Voltage 0.5 V VOH High-Level Output Voltage 0.8 Units VIL 2 VCC e MIN VIL e 0.8V VIH e 2V VCC e MIN VIL e 0.8V VIH e 2V Off-State Output Current VCC e MAX VIL e 0.8V VIH e 2V IOS Output Short-Circuit Current* VCC e 5.0V ICC Supply Current VCC e MAX IOZL IOZH MIL IOL e 12 mA COM IOL e 24 mA MIL IOH eb2 mA COM V V 2.4 V IOH eb3.2 mA VO e 0.4V b 100 VO e 2.4V VCC e 0V b 30 120 mA 100 mA b 130 mA 180 mA *No more than one output should be shorted at a time and duration of the short-circuit should not exceed one second ² All typical values are at VCC e 5V, TA e 25§ C. Switching Characteristics Over Operating Conditions Symbol Parameter fMAX Maximum Clock Frequency tPD CBI to CBO Delay tPD Clock to Q tPD Clock to CO tPZX Output Enable Delay tPXZ Output Disable Delay Test Conditions (See Test Load) Military Min Commercial Typ Max 35 CL e 50 pF R1 e 200 X R2 e 390 X 2 Units Typ Max 60 35 50 ns 20 35 20 30 ns 55 95 55 80 ns 35 55 35 45 ns 35 55 35 45 ns 10.5 Min 12.5 MHz Logic Diagram LS461 TL/L/8334 – 3 3 DM54LS461/DM74LS461 Octal Counter Physical Dimensions inches (millimeters) 24-Pin Narrow Ceramic Dual-In-Line Package (J) Order Number DM54LS461J or DM74LS461J NS Package J24F LIFE SUPPORT POLICY 24-Pin Narrow Plastic Dual-In-Line Package (N) Order Number DM74LS461N NS Package N24C 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. 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 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. National Semiconductor Corporation 1111 West Bardin Road Arlington, TX 76017 Tel: 1(800) 272-9959 Fax: 1(800) 737-7018 2. A critical component is 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. 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