SN54/74LS147 SN54/74LS148 SN54/74LS748 10-LINE-TO-4-LINE AND 8-LINE-TO-3-LINE PRIORITY ENCODERS The SN54 / 74LS147 and the SN54 / 74LS148 are Priority Encoders. They provide priority decoding of the inputs to ensure that only the highest order data line is encoded. Both devices have data inputs and outputs which are active at the low logic level. The LS147 encodes nine data lines to four-line (8-4-2-1) BCD. The implied decimal zero condition does not require an input condition because zero is encoded when all nine data lines are at a high logic level. The LS148 encodes eight data lines to three-line (4-2-1) binary (octal). By providing cascading circuitry (Enable Input EI and Enable Output EO) octal expansion is allowed without needing external circuitry. The SN54 / 74LS748 is a proprietary Motorola part incorporating a built-in deglitcher network which minimizes glitches on the GS output. The glitch occurs on the negative going transition of the EI input when data inputs 0 - 7 are at logical ones. The only dc parameter differences between the LS148 and the LS748 are that (1) Pin 10 (input 0) has a fan-in of 2 on the LS748 versus a fan-in of 1 on the LS148; (2) Pins 1, 2, 3, 4, 11, 12 and 13 (inputs 1, 2, 3, 4, 5, 6, 7) have a fan-in of 3 on the LS748 versus a fan-in of 2 on the LS148. The only ac difference is that tPHL from EI to EO is changed from 40 to 45 ns. SN54 / 74LS147 (TOP VIEW) OUTPUT VCC 16 INPUTS 10-LINE-TO-4-LINE AND 8-LINE-TO-3-LINE PRIORITY ENCODERS LOW POWER SCHOTTKY J SUFFIX CERAMIC CASE 620-09 16 1 N SUFFIX PLASTIC CASE 648-08 16 1 OUTPUT NC D 3 2 1 9 A 15 14 13 12 11 10 9 D 3 2 1 9 16 1 4 1 4 A 5 6 7 8 C B 2 5 3 6 4 7 5 8 6 C 7 B INPUTS ORDERING INFORMATION SN54LSXXXJ SN74LSXXXN SN74LSXXXD 8 GND OUTPUTS SN54 / 74LS148 SN54 / 74LS748 (TOP VIEW) INPUTS OUTPUTS VCC 16 1 4 OUTPUT EO GS 3 2 1 0 A0 15 14 13 12 11 10 9 EO GS 3 2 1 0 4 A0 5 6 7 EI A2 A1 2 5 3 6 4 7 5 E1 6 A2 7 A1 INPUTS D SUFFIX SOIC CASE 751B-03 8 GND OUTPUTS FAST AND LS TTL DATA 5-1 Ceramic Plastic SOIC SN54/74LS147 * SN54/74LS148 * SN54/74LS748 SN54 / 74LS148 SN54 / 74LS748 FUNCTION TABLE SN54 / 74LS147 FUNCTION TABLE INPUTS OUTPUTS INPUTS OUTPUTS 1 2 3 4 5 6 7 8 9 D C B A EI 0 1 2 3 4 5 6 7 A2 A1 A0 GS EO H X X X X X X X X L H X X X X X X X L H H X X X X X X L H H H X X X X X L H H H H X X X X L H H H H H X X X L H H H H H H X X L H H H H H H H X L H H H H H H H H L H H H H H H H H H L L H H H H H H H H H H L L L L H H H H H H L L H H L L H H L H L H L H L H L H L L L L L L L L L X H X X X X X X X L X H X X X X X X L H X H X X X X X L H H X H X X X X L H H H X H X X X L H H H H X H X X L H H H H H X H X L H H H H H H X H L H H H H H H H H H L L L L H H H H H H L L H H L L H H H H L H L H L H L H H H L L L L L L L L H L H H H H H H H H H = HIGH Logic Level, L = LOW Logic Level, X = Irrelevant FUNCTIONAL BLOCK DIAGRAMS 1 2 3 (11) 0 (12) (9) 1 A (13) 2 (10) (15) (11) (14) 5 6 7 8 9 (1) 3 (7) (2) B 4 (3) (13) (7) (2) (6) 6 C (5) (4) (14) (6) (5) D EI SN54 / 74LS147 SN54 / 74LS148 FAST AND LS TTL DATA 5-2 A1 (3) 7 (10) A0 (1) 5 (4) GS (12) (8) 4 EO A2 SN54/74LS147 * SN54/74LS148 * SN54/74LS748 FUNCTIONAL BLOCK DIAGRAMS (continued) G31 (10) 0 G13 (15) (14) (11) 1 G2 EO GS G29 G9 (12) 2 (9) G3 (13) 3 A0 G18 G4 G10 4 (1) G5 5 (7) G11 (2) G6 6 A1 G23 G12 (3) G7 7 (4) (6) G8 EI G28 (5) G1 SN54 / 74LS748 FAST AND LS TTL DATA 5-3 A2 SN54/74LS147 * SN54/74LS148 * SN54/74LS748 GUARANTEED OPERATING RANGES Symbol Parameter Min Typ Max Unit VCC Supply Voltage 54 74 4.5 4.75 5.0 5.0 5.5 5.25 V TA Operating Ambient Temperature Range 54 74 - 55 0 25 25 125 70 C IOH Output Current -- High 54, 74 - 0.4 mA IOL Output Current -- Low 54 74 4.0 8.0 mA DC CHARACTERISTICS OVER OPERATING TEMPERATURE RANGE (unless otherwise specified) Limits S b l Symbol P Parameter VIH Input HIGH Voltage VIL Input LOW Voltage VIK Input Clamp Diode Voltage VOH Output HIGH Voltage VOL Output LOW Voltage IIH Min Typ Max U i Unit 2.0 54 0.7 74 0.8 - 0.65 - 1.5 T Test C Conditions di i V Guaranteed Input HIGH Voltage for All Inputs V Guaranteed Input p LOW Voltage g for All Inputs V VCC = MIN, IIN = - 18 mA 54 2.5 3.5 V 74 2.7 3.5 V VCC = MIN,, IOH = MAX,, VIN = VIH or VIL per Truth Table VCC = VCC MIN, VIN = VIL or VIH per Truth Table 54, 74 0.25 0.4 V IOL = 4.0 mA 74 0.35 0.5 V IOL = 8.0 mA A VCC = MAX, VIN = 2.7 V mA VCC = MAX, VIN = 7.0 V mA VCC = MAX, VIN = 0.4 V - 100 mA VCC = MAX Input HIGH Current All Others Input 0 (LS748) Inputs 1 - 7 (LS148) Inputs 1 - 7 (LS748) 20 40 40 60 All Others Input 0 (LS748) Inputs 1 - 7 (LS148) Inputs 1 - 7 (LS748) 0.1 0.2 0.2 0.3 IIL Input LOW Current All Others Input 0 (LS748) Inputs 1 - 7 (LS148) Inputs 1 - 7 (LS748) IOS Short Circuit Current (Note 1) ICCH Power Supply Current Output HIGH 17 mA VCC = MAX, All Inputs = 4.5 V ICCL Output LOW 20 mA VCC = MAX, Inputs 7 & E1 = GND All Other Inputs = 4.5 V - 0.4 - 0.8 - 0.8 - 1.2 - 20 Note 1: Not more than one output should be shorted at a time, nor for more than 1 second. FAST AND LS TTL DATA 5-4 SN54/74LS147 * SN54/74LS148 * SN54/74LS748 AC CHARACTERISTICS (VCC = 5.0 V, TA = 25C) SN54 / 74LS147 S b l Symbol tPLH From (Input) To (Output) Any Any tPHL tPLH Any Any tPHL Limits W Waveform f Min Typ Max In-phase p output 12 18 12 18 Out-of-phase p output 21 33 15 23 U i Unit T Test C Conditions di i ns CL = 15 p pF, F, RL = 2.0 k ns SN54 / 74LS148 SN54 / 74LS748 S b l Symbol tPLH From (Input) To (Output) 1 thru 7 A0 A1 A0, A1, or A2 tPHL tPLH 1 thru 7 A0 A1 A0, A1, or A2 tPHL tPLH 0 thru 7 EO tPHL tPLH 0 thru 7 GS tPHL tPLH EI A0 A1 A0, A1, or A2 tPHL tPLH EI GS tPHL tPLH tPHL EI EO Limits W Waveform f Min Typ Max In-phase p output 14 18 15 25 Out-of-phase p output 20 36 16 29 Out-of-phase p output 7.0 18 25 40 In-phase p output 35 55 U i Unit T Test C Conditions di i ns ns ns ns 9.0 21 In-phase p output 16 25 12 25 In-phase p output 12 17 14 36 12 21 28 30 40 45 F CL = 15 pF pF, RL = 2.0 k ns ns In-phase output FAST AND LS TTL DATA 5-5 ns (LS148) (LS748)