SN74AS298A QUADRUPLE 2-INPUT MULTIPLEXER WITH STORAGE SDAS219B – DECEMBER 1983 – REVISED DECEMBER 1994 • • • D OR N PACKAGE (TOP VIEW) Selects One of Two 4-Bit Data Sources and Synchronously Stores Data With System Clock Applications: – Dual Source for Operands and Constants in Arithmetic Processor; Can Release Processor Register Files for Acquiring New Data – Implements Separate Registers Capable of Parallel Exchange of Contents, Yet Retains External Load Capability – Has Universal-Type Register for Implementing Various Shift Patterns, Including Compound Left-Right Capability Package Options Include Plastic Small-Outline (D) Packages and Standard Plastic (N) 300-mil DIPs B2 A2 A1 B1 C2 D2 D1 GND 1 16 2 15 3 14 4 13 5 12 6 11 7 10 8 9 VCC QA QB QC QD CLK WS C1 description The SN74AS298A is a quadruple 2-input multiplexer with storage that provides essentially the equivalent functional capabilities of two separate MSI functions (SN74AS157 and ′AS175A) in a 16-pin package. When the word-select (WS) input is low, word 1 (A1, B1, C1, D1) is applied to the flip-flops. A high input to WS causes the selection of word 2 (A2, B2, C2, D2). The selected word is clocked to the output terminals on the negative-going edge of the clock pulse. The SN74AS298A is characterized for operation from 0°C to 70°C. FUNCTION TABLE OUTPUTS† INPUTS WS CLK QA QB QC L ↓ a1 b1 c1 QD d1 H ↓ a2 b2 c2 d2 X H QA0 QB0 QC0 QD0 † a1, a2, etc. = the level of steady-state input at A1, A2, etc. QA0, QB0, etc. = the level of QA, QB, etc. entered on the most recent ↓ transition of CLK Copyright 1994, Texas Instruments Incorporated PRODUCTION DATA information is current as of publication date. Products conform to specifications per the terms of Texas Instruments standard warranty. Production processing does not necessarily include testing of all parameters. POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 1 SN74AS298A QUADRUPLE 2-INPUT MULTIPLEXER WITH STORAGE SDAS219B – DECEMBER 1983 – REVISED DECEMBER 1994 logic symbol† WS CLK A1 A2 B1 B2 C1 C2 D1 D2 10 11 MUX G1 C2 3 2 15 1, 2D 1, 2D QA 4 14 1 QB 9 13 5 QC 7 12 6 QD † This symbol is in accordance with ANSI/IEEE Std 91-1984 and IEC Publication 617-12. logic diagram (positive logic) A1 WS 3 10 1S A2 B1 C1 2 15 QA 1R 4 1S B2 C1 1 14 QB 1R C1 9 1S C2 C1 5 13 QC 1R D1 7 1S D2 C1 6 1R CLK 2 11 POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 12 QD SN74AS298A QUADRUPLE 2-INPUT MULTIPLEXER WITH STORAGE SDAS219B – DECEMBER 1983 – REVISED DECEMBER 1994 absolute maximum ratings over operating free-air temperature range (unless otherwise noted)† Supply voltage, VCC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 V Input voltage, VI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 V Operating free-air temperature range, TA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0°C to 70°C Storage temperature range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65°C to 150°C † Stresses beyond those listed under “absolute maximum ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated under “recommended operating conditions” is not implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability. recommended operating conditions MIN NOM MAX 4.5 5 5.5 UNIT VCC VIH Supply voltage VIL IOH Low-level input voltage 0.8 V High-level output current –2 mA IOL TA Low-level output current 20 mA 70 °C High-level input voltage 2 Operating free-air temperature V V 0 electrical characteristics over recommended operating free-air temperature range (unless otherwise noted) PARAMETER TEST CONDITIONS VIK VOH VCC = 4.5 V, VCC = 4.5 V to 5.5 V, II = – 18 mA IOH = – 2 mA VOL II VCC = 4.5 V, VCC = 5.5 V, IOL = 20 mA VI = 7 V VCC = 5 5.5 5V V, VI = 2 2.7 7V 5V VCC = 5 5.5 V, 4V VI = 0 0.4 VCC = 5.5 V, VCC = 5.5 V VO = 2.25 V IIH IIL WS All others WS All others IO§ ICCH MIN TYP‡ MAX UNIT – 1.2 V VCC – 2 V 0.35 0.5 V 0.1 mA 40 20 – 0.75 – 0.5 – 30 21 µA mA – 112 mA 33 mA ICCL VCC = 5.5 V 22 36 mA ‡ All typical values are at VCC = 5 V, TA = 25°C. § The output conditions have been chosen to produce a current that closely approximates one half of the true short-circuit output current, IOS. timing requirements over recommended operating free-air temperature range (unless otherwise noted) MIN MAX UNIT 62 MHz fclock tw Clock frequency 0 Pulse duration, CLK high or low 8 tsu Setup time before CLK↓ th Hold time after CLK↓ Data 4.5 WS 13 Data 3.5 WS POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 1 ns ns ns 3 SN74AS298A QUADRUPLE 2-INPUT MULTIPLEXER WITH STORAGE SDAS219B – DECEMBER 1983 – REVISED DECEMBER 1994 switching characteristics over recommended ranges of supply voltage and operating free-air temperature, CL = 50 pF (unless otherwise noted) (see Figure 3) FROM (INPUT) PARAMETER fmax tPLH TO (OUTPUT) MIN MAX 62 CLK tPHL Q UNIT MHz 2 9 1 11 ns APPLICATION INFORMATION This versatile multiplexer can be connected to operate as a shift register that can shift n places in a single clock pulse. Figure 1 illustrates a BCD shift register that shifts an entire 4-bit BCD digit in one clock pulse. Parallel Load WS CLK SN74AS298A SN74AS298A MUX G1 C2 SN74AS298A MUX MUX G1 C2 A1 1, 2D A2 1, 2D B1 B2 C1 C2 D1 D2 G1 C2 QA QB QC QD A1 1, 2D A2 1, 2D B1 B2 C1 C2 D1 D2 Digit 1 QA QB QC QD Digit 2 A1 A2 B1 B2 C1 C2 D1 D2 1, 2D 1, 2D QA QB QC QD Digit 3 Figure 1. BCD Shift Register When WS is high and the registers are clocked, the content of register 1 is transferred (shifted) to register 2, etc., effectively shifting the BCD digits one position. This application also retains a parallel-load capability, which means that new BCD data can be entered into the entire register with one clock pulse. This arrangement can be modified to perform the shifting of binary data for any number of bit locations. Another function that can be implemented is a register designed specifically for supporting multiplier or division operations (see Figure 2). When WS is low and the register is clocked, the outputs of the arithmetic / logic units (ALUs) are shifted one place. When WS is high and the registers are clocked, the data is shifted two places. 4 POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 SN74AS298A QUADRUPLE 2-INPUT MULTIPLEXER WITH STORAGE SDAS219B – DECEMBER 1983 – REVISED DECEMBER 1994 APPLICATION INFORMATION SN74AS298A MUX G1 C2 WS CLK F0 ′AS181A F1 F2 A1 A2 B1 B2 C1 C2 D1 D2 1, 2D 1, 2D QA QB QC QD F3 SN74AS298A MUX G1 C2 F0 ′AS181A F1 F2 A1 A2 B1 B2 C1 C2 D1 D2 1, 2D 1, 2D QA QB QC QD F3 Figure 2. 1-Place / 2-Place Shift Register POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 5 SN74AS298A QUADRUPLE 2-INPUT MULTIPLEXER WITH STORAGE SDAS219B – DECEMBER 1983 – REVISED DECEMBER 1994 PARAMETER MEASUREMENT INFORMATION SERIES 54ALS/74ALS AND 54AS/74AS DEVICES 7V RL = R1 = R2 VCC S1 RL R1 Test Point From Output Under Test CL (see Note A) From Output Under Test RL Test Point From Output Under Test CL (see Note A) CL (see Note A) LOAD CIRCUIT FOR BI-STATE TOTEM-POLE OUTPUTS LOAD CIRCUIT FOR OPEN-COLLECTOR OUTPUTS 3.5 V Timing Input Test Point LOAD CIRCUIT FOR 3-STATE OUTPUTS 3.5 V High-Level Pulse 1.3 V R2 1.3 V 1.3 V 0.3 V 0.3 V Data Input tw th tsu 3.5 V 1.3 V 3.5 V Low-Level Pulse 1.3 V 0.3 V 1.3 V 0.3 V VOLTAGE WAVEFORMS SETUP AND HOLD TIMES VOLTAGE WAVEFORMS PULSE DURATIONS 3.5 V Output Control (low-level enabling) 1.3 V 1.3 V 0.3 V tPZL Waveform 1 S1 Closed (see Note B) tPLZ [3.5 V 1.3 V tPHZ tPZH Waveform 2 S1 Open (see Note B) 1.3 V VOL 0.3 V VOH 1.3 V 0.3 V [0 V 3.5 V 1.3 V Input 1.3 V 0.3 V tPHL tPLH VOH In-Phase Output 1.3 V 1.3 V VOL tPLH tPHL VOH Out-of-Phase Output (see Note C) 1.3 V 1.3 V VOL VOLTAGE WAVEFORMS PROPAGATION DELAY TIMES VOLTAGE WAVEFORMS ENABLE AND DISABLE TIMES, 3-STATE OUTPUTS NOTES: A. CL includes probe and jig capacitance. B. Waveform 1 is for an output with internal conditions such that the output is low except when disabled by the output control. Waveform 2 is for an output with internal conditions such that the output is high except when disabled by the output control. C. When measuring propagation delay items of 3-state outputs, switch S1 is open. D. All input pulses have the following characteristics: PRR ≤ 1 MHz, tr = tf = 2 ns, duty cycle = 50%. E. The outputs are measured one at a time with one transition per measurement. Figure 3. Load Circuits and Voltage Waveforms 6 POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 IMPORTANT NOTICE Texas Instruments and its subsidiaries (TI) reserve the right to make changes to their products or to discontinue any product or service without notice, and advise customers to obtain the latest version of relevant information to verify, before placing orders, that information being relied on is current and complete. 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