DM54148 Priority Encoder General Description Features This TTL encoder features priority decoding of the input data to ensure that only the highest-order data line is encoded. The DM54148 encodes eight data lines to three-line (4-2-1) binary (octal). Cascading circuitry (enable input E1 and enable output E0) has been provided to allow octal expansion without the need for external circuitry. For all types, data inputs and outputs are active at the low logic level. Y Y Encodes 8 data lines to 3-line binary (octal) Applications include: N-bit encoding Code converters and generators Connection Diagram Dual-In-Line Package TL/F/6545 - 1 Order Number DM54148J or DM54148W See NS Package Number J16A or W16A Function Table DM54148 Inputs Outputs E1 0 1 2 3 4 5 6 7 A2 A1 A0 GS E0 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 e High Logic Level, L e Low Logic Level, X e Don't Care C1995 National Semiconductor Corporation TL/F/6545 RRD-B30M105/Printed in U. S. A. DM54148 Priority Encoder June 1989 Absolute Maximum Ratings (Note) Note: 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'' table are not guaranteed at the absolute maximum ratings. The ``Recommended Operating Conditions'' table will define the conditions for actual device operation. If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/Distributors for availability and specifications. Supply Voltage 7V Input Voltage 5.5V Operating Free Air Temperature Range b 55 C to a 125 C DM54 b 65 C to a 150 C Storage Temperature Range Recommended Operating Conditions Symbol DM54148 Parameter VCC Supply Voltage VIH High Level Input Voltage VIL Low Level Input Voltage IOH High Level Output Current IOL Low Level Output Current TA Free Air Operating Temperature Units Min Nom Max 4.5 5 5.5 V 2 V b 55 0.8 V b 0.8 mA 16 mA 125 C Electrical Characteristics over recommended operating free air temperature range (unless otherwise noted) Symbol Parameter Conditions Min VI Input Clamp Voltage VCC e Min, II e b12 mA VOH High Level Output Voltage VCC e Min, IOH e Max VIL e Max, VIH e Min VOL Low Level Output Voltage VCC e Min, IOL e Max VIH e Min, VIL e Max II Input Current @ Max Input Voltage IIH Typ (Note 1) Max Units b 1.5 V 2.4 V 0.4 V VCC e Max, VI e 5.5V 1 mA High Level Input Current VCC e Max VI e 2.4V 0 Input 40 Others 80 Low Level Input Current VCC e Max VI e 0.4V 0 Input b 1.6 Others b 3.2 IOS Short Circuit Output Current VCC e Max (Note 2) ICC1 Supply Current VCC e Max (Note 3) ICC2 Supply Current VCC e Max (Note 4) IIL Note 1: All typicals are at VCC e 5V, TA e 25 C. Note 2: Not more than one output should be shorted at a time. Note 3: ICC1 is measured with inputs E1 and 7 grounded, other inputs and outputs open. Note 4: ICC2 is measured with all inputs and all outputs open. 2 b 35 mA mA b 85 mA 40 60 mA 35 55 mA Switching Characteristics at VCC e 5V and TA e 25 C (See Section 1 for Test Waveforms and Output Load) Symbol tPLH Parameter From (Input) To (Output) Propagation Delay Time Low to High Level Output 0 thru 7 to A0, 1, 2 tPHL Propagation Delay Time High to Low Level Output 0 thru 7 to A0, 1, 2 tPLH Propagation Delay Time Low to High Level Output 0 thru 7 to A0, 1, 2 tPHL Propagation Delay Time High to Low Level Output 0 thru 7 to A0, 1, 2 tPLH Propagation Delay Time Low to High Level Output 0 thru 7 to E0 tPHL Propagation Delay Time High to Low Level Output 0 thru 7 to E0 tPLH Propagation Delay Time Low to High Level Output 0 thru 7 to GS tPHL Propagation Delay Time High to Low Level Output 0 thru 7 to GS tPLH Propagation Delay Time Low to High Level Output E1 to A0, 1, 2 tPHL Propagation Delay Time High to Low Level Output E1 to A0, 1, 2 tPLH Propagation Delay Time Low to High Level Output E1 to GS tPHL Propagation Delay Time High to Low Level Output E1 to GS tPLH Propagation Delay Time Low to High Level Output E1 to E0 Propagation Delay Time High to Low Level Output E1 to E0 tPHL Waveform RL e 400X, CL e 15 pF Min In-Phase Output Out-of-Phase Output Out-of-Phase Output In-Phase Output In-Phase Output In-Phase Output In-Phase Output 3 Units Max 15 ns 14 ns 19 ns 19 ns 10 ns 25 ns 30 ns 25 ns 16 ns 15 ns 13 ns 15 ns 15 ns 30 ns Logic Diagram TL/F/6545 - 2 4 Physical Dimensions inches (millimeters) 16-Lead Ceramic Dual-In-Line Package (J) Order Number DM54148J NS Package Number J16A 5 DM54148 Priority Encoder Physical Dimensions inches (millimeters) (Continued) 16-Lead Ceramic Flat Package (W) Order Number DM54148W NS Package Number W16A LIFE SUPPORT POLICY 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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