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Part: 74F381PC
Category:
Description: 4-Bit Arithmetic Logic Unit
Company: Fairchild Semiconductor
Datasheet: Download 74F381PC datasheet File size : 222 kB
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74F381 4-Bit Arithmetic Logic Unit
May 1988 Revised October 2000
74F381 4-Bit Arithmetic Logic Unit
General Description
The 74F381 performs three arithmetic and three logic operations on two 4-bit words, A and B. Two additional select input codes force the function outputs LOW or HIGH. Carry propagate and generate outputs are provided for use with the 74F182 carry lookahead generator for high-speed expansion to longer word lengths. For ripple expansion, refer to the 74F382 ALU data sheet.
Features
s Low input loading minimizes drive requirements s Performs six arithmetic and logic functions s Selectable LOW (clear) and HIGH (preset) functions s Carry generate and propagate outputs for use with carry lookahead generator
Ordering Code:
Order Number 74F381SC 74F381SJ 74F381PC Package Number M20B M20D N20A Package Description 20-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-013, 0.300 Wide 20-Lead Small Outline Package (SOP), EIAJ TYPE II, 5.3mm Wide 20-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.
Logic Symbols
Connection Diagram
IEEE/IEC
© 2000 Fairchild Semiconductor Corporation
DS009528
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74F381
Unit Loading/Fan Out
Pin Names A0A3 B0B3 S0S2 Cn G P F0F3 Description A Operand Inputs B Operand Inputs Function Select Inputs Carry Input Carry Generate Output (Active LOW) Carry Propagate Output (Active LOW) Function Outputs U.L . HIGH/LOW 1.0/3.0 1.0/3.0 1.0/1.0 1.0/4.0 50/33.3 50/33.3 50/33.3 Input IIH/IIL Output IOH/IOL 20 µA/-1.8 mA 20 µA/-1.8 mA 20 µA/-0.6 mA 20 µA/-2.4 mA
-1 mA/20 mA -1 mA/20 mA -1 mA/20 mA
Functional Description
Signals applied to the Select inputs S0S2 determine the mode of operation, as indicated in the Function Select Table. An extensive listing of input and output levels is shown in the Truth Table. The circuit performs the arithmetic functions for either active HIGH or active LOW operands, with output levels in the same convention. In the Subtract operating modes, it is necessary to force a carry (HIGH for active HIGH operands, LOW for active LOW operands) into the Cn input of the least significant package. The Carry Generate (G) and Carry Propagate (P) outputs supply input signals to the 74F182 carry lookahead generator for expansion to longer word length, as shown in Figure 2. Note that an 74F382 ALU is used for the most significant package. Typical delays for Figure 2 are given in Figure 1.
Function Select Table
Select S0 L H L H L H L H
H = HIGH Voltage Level L = LOW Voltage Level
S1 L L H H L L H H
S2 L L L L H H H H
Operation Clear B Minus A A Minus B A Plus B A B A+B AB Preset
Toward Path Segment Ai or Bi to P Pi to Cn + ('F182) Cn to F Cn or Cn + 4, OVR Total Delay F 7.2 ns 6.2 ns 8.1 ns -- 21.5 ns
Output Cn + 4, OVR 7.2 ns 6.2 ns -- 8.0 ns 21.4 ns
FIGURE 1. 16-Bit Delay Tabulation
FIGURE 2. 16-Bit Lookahead Carry ALU Expansion
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74F381
Truth Table
Inputs Function CLEAR S0 L S1 L S2 L Cn X L L L B Minus A H L L L H H H H L L L A Minus B L H L L H H H H L L L A Plus B H H L L H H H H X X AB L L H X X X X A+B H L H X X X X AB L H H X X X X PRESET
H = HIGH Voltage Level L = LOW Voltage Level X = Immaterial
Outputs An X L L H H L L H H L L H H L L H H L L H H L L H H L L H H L L H H L L H H L L H H Bn X L H L H L H L H L H L H L H L H L H L H L H L H L H L H L H L H L H L H L H L H F0 L H L L H L H H L H L L H L H H L L H H L H L L H L H H L L H H H L L L H H H H H F1 L H H L H L H L L H L H H L L H L L H H H L L L H L H H L L H H H L L L H H H H H F2 L H H L H L H L L H L H H L L H L L H H H L L L H L H H L L H H H L L L H H H H H F3 L H H L H L H L L H L H H L L H L L H H H L L L H L H H L L H H H L L L H H H H H G L H L H H H L H H H H L H H H L H H H H L H H H L H H H L H H H H L H L H H H H H P L L L H L L L H L L H L L L H L L H L L L H L L L H H L L H H H L L H L L H H H L
H
H
H
X X
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74F381
Logic Diagram
Please note that this diagram is provided only for the understanding of logic operations and should not be used to estimate propagation delays.
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74F381
Absolute Maximum Ratings(Note 1)
Storage Temperature Ambient Temperature under Bias Junction Temperature under Bias VCC Pin Potential to Ground Pin Input Voltage (Note 2) Input Current (Note 2) Voltage Applied to Output in HIGH State (with VCC = 0V) Standard Output 3-STATE Output Current Applied to Output in LOW State (Max) twice the rated IOL (mA)
-65°C to +150°C -55°C to +125°C -55°C to +150°C -0.5V to +7.0V -0.5V to +7.0V -30 mA to +5.0 mA
Recommended Operating Conditions
Free Air Ambient Temperature Supply Voltage 0°C to +70°C
+4.5V to +5.5V
-0.5V to VCC -0.5V to +5.5V
Note 1: Absolute maximum ratings are values beyond which the device may be damaged or have its useful life impaired. Functional operation under these conditions is not implied. Note 2: Either voltage limit or current limit is sufficient to protect inputs.
DC Electrical Characteristics
Symbol VIH VIL VCD VOH VOL IIH IBVI ICEX VID IOD IIL Parameter Input HIGH Voltage Input LOW Voltage Input Clamp Diode Voltage Output HIGH Voltage Output LOW Voltage Input HIGH Current Input HIGH Current Breakdown Test Output HIGH Leakage Current Input Leakage Test Output Leakage Circuit Current Input LOW Current 4.75 3.75 -0.6 -1.8 -2.4 IOS ICC Output Short-Circuit Current Power Supply Current -60 59 -150 89 10% VCC 5% VCC 10% VCC 2.5 2.7 0.5 5.0 7.0 50 M in 2.0 0.8 -1.2 Typ Max Units V V V V V µA µA µA V µA mA mA mA mA mA Max Max 0 .0 0 .0 Max Max Max Max Max Min Min Min V CC Conditions Recognized as a HIGH Signal Recognized as a LOW Signal IIN = -18 mA IOH = -1 mA IOH = -1 mA IOL = 20 mA VIN = 2.7V VIN = 7.0V VOUT = VCC IID = 1.9 µA All Other Pins Grounded VIOD = 150 mV All Other Pins Grounded VIN = 0.5V (Sn) VIN = 0.5V (An, Bn) VIN = 0.5V (Cn) VOUT = 0V
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