Revised March 2000 DM74S182 Look-Ahead Carry Generator General Description These circuits are high-speed, look-ahead carry generators, capable of anticipating a carry across four binary adders or groups of adders. They are cascadable to perform full look-ahead across n-bit adders. Carry, generatecarry, and propagate-carry functions are provided as shown in the pin designation table. When used in conjunction with the 181 arithmetic logic unit, these generators provide high-speed carry look-ahead capability for any word length. Each DM74S182 generates the look-ahead (anticipated carry) across a group of four ALU’s and, in addition, other carry look-ahead circuits may be employed to anticipate carry across sections of four look-ahead packages up to n-bits. The method of cascading circuits to perform multi-level look-ahead is illustrated under typical application data. Carry input and output of the ALU’s are in their true form, and the carry propagate (P) and carry generate (G) are in negated form; therefore, the carry functions (inputs, out- puts, generate, and propagate) of the look-ahead generators are implemented in the compatible forms for direct connection to the ALU. Reinterpretations of carry functions, as explained on the 181 data sheet are also applicable to and compatible with the look-ahead generator. Positive logic equations for the DM74S182 are: Cn + x = G0 + P0 Cn Cn + y = G1 + P1 G0 + P1 P0 Cn Cn + z = G2 + P2 G1 + P2 P1 G0 + P2 P1 P0 Cn G = G3 (P3 + G2) (P3 + P2 + G1) (P3 + P2 + P1 + G0) P = P3 P2 P1 P0 Features ■ Typical propagation delay time 7 ns ■ Typical power dissipation 260 mW Ordering Code: Order Number DM74S182N Package Number N16E Package Description 16-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300 Wide Connection Diagram Pin Designations Designation Pin Nos. Function G0, G1, G2, G3 3, 1, 14, 5 Active LOW P0, P1, P2, P3 4, 2, 15, 6 Carry Generate Inputs Active LOW Carry Propagate Inputs Cn 13 Carry Input Cn + x, Cn + y, 12, 11, 9 Carry Outputs Cn + z G 10 Active LOW Carry Generate Output P 7 Active LOW Carry Propagate Output © 2000 Fairchild Semiconductor Corporation DS006474 VCC 16 Supply Voltage GND 8 Ground www.fairchildsemi.com DM74S182 Look-Ahead Carry Generator August 1986 DM74S182 Logic Diagram VCC = PIN 16 GND = PIN 8 Typical Application 64-Bit ALU, Full-Carry Look Ahead in Three Levels A and B inputs, and F outputs of 181 are not shown. 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 5.5V 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 Units 4.75 5 5.25 V LOW Level Input Voltage 0.8 V VCC Supply Voltage VIH HIGH Level Input Voltage VIL 2 V IOH HIGH Level Output Current −1 mA IOL LOW Level Output Current 20 mA TA Free Air Operating Temperature 70 °C 0 Electrical Characteristics over recommended operating free air temperature (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 LOW Level VCC = Min, IOL = Max Output Voltage VIH = Min, VIL = Max VOL Min 2.7 Typ (Note 2) Max Units −1.2 V 3.4 V 0.5 V II Input Current @ Max Input Voltage VCC = Max, VI = 5.5V 1 mA IIH HIGH Level VCC = Max P0, P1 or G3 200 µA Input Current VI = 2.7V P3 100 P2 150 IIL Cn 50 G0, G2 350 G1 400 LOW Level VCC = Max P0, P1 or G3 −8 Input Current VI = 0.5V P3 −4 P2 −6 Cn −2 G0, G2 −14 −16 G1 VCC = Max (Note 3) IOS Short Circuit Output Current ICCH Supply Current with Outputs HIGH VCC = Max (Note 4) ICCL Supply Currents with Outputs LOW VCC = Max (Note 5) mA −40 −100 mA 39 55 mA 69 109 mA Note 2: All typicals are at VCC = 5V, TA = 25°C. Note 3: Not more than one output should be shorted at a time, and the duration should not exceed one second. Note 4: ICCH is measured with all outputs OPEN, inputs P3 and G3 at 4.5V, and all other inputs grounded. Note 5: ICCL is measured with all outputs OPEN, inputs G0, G1, and G2 at 4.5V, and all other inputs grounded. 3 www.fairchildsemi.com DM74S182 Absolute Maximum Ratings(Note 1) DM74S182 Switching Characteristics at VCC = 5V and TA = 25°C RL = 280Ω Symbol Parameter From (Input) To (Output) tPLH Propagation Delay Time LOW-to-HIGH Level Output tPHL Propagation Delay Time HIGH-to-LOW Level Output tPLH Propagation Delay Time LOW-to-HIGH Level Output tPHL Propagation Delay Time HIGH-to-LOW Level Output tPLH Propagation Delay Time LOW-to-HIGH Level Output tPHL Propagation Delay Time HIGH-to-LOW Level Output tPLH Propagation Delay Time LOW-to-HIGH Level Output tPHL Propagation Delay Time HIGH-to-LOW Level Output www.fairchildsemi.com CL = 15 pF Min CL = 50 pF Max Min Units Min GN or PN to Cn + x, y, z 7 10 ns GN or PN to Cn + x, y, z 7 11 ns GN or PN to G 7.5 11 ns GN or PN to G 10.5 14 ns PN to P 6.5 10 ns PN to P 10 14 ns Cn to to Cn + x, y, z 10 13 ns Cn to to Cn + x, y, z 10.5 14 ns 4 DM74S182 Look-Ahead Carry Generator 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 5 www.fairchildsemi.com