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| HD74HC149 8-to-8-line Priority Encoder Description The HD74HC149 is priority encoder which has 8 input lines (0 - 7) and 8 output lies (Y0 - Y7). It is the logical combination of a HD74HC148 8-3 line priority encoder driving a HD74HC138 3-8 line decoder. Only one request output can be low at a time. The output that is low is dependent on the highest priority request that is low. The order of priority is 7 highest and 0 lowest. When E input is high, all outputs are high. When a output (Y0 - Y 7) is low, P output is low and this indicates active condition. Features * * * * * High Speed Operation: tpd (0 - 7 to Y) = 16 ns typ (CL = 50 pF) High Output Current: Fanout of 10 LSTTL Loads Wide Operating Voltage: VCC = 2 to 6 V Low Input Current: 1 A max Low Quiescent Supply Current: ICC (static) = 4 A max (Ta = 25C) HD74HC149 Function Table Inputs 0 X H X X X X X X X L H: L: X: 1 X H X X X X X X L H 2 X H X X X X X L H H 3 X H X X X X L H H H 4 X H X X X L H H H H 5 X H X X L H H H H H 6 X H X L H H H H H H 7 X H L H H H H H H H E H L L L L L L L L L Outputs Y0 H H H H H H H H H L Y1 H H H H H H H H L H Y2 H H H H H H H L H H Y3 H H H H H H L H H H Y4 H H H H H L H H H H Y5 H H H H L H H H H H Y6 H H H L H H H H H H Y7 H H L H H H H H H H P H H L L L L L L L L High level Low level Irrelevant Pin Arrangement 0 1 2 3 Inputs 4 5 6 7 E 1 2 3 4 5 6 7 8 9 20 VCC 19 Y0 18 Y1 17 Y2 16 Y3 15 Y4 14 Y5 13 Y6 12 Y7 11 P (Top view) Outputs GND 10 2 HD74HC149 Logic Diagram 7 Y7 6 Y6 5 Y5 4 Y4 3 Y3 2 Y2 1 Y1 0 Y0 P E 3 HD74HC149 DC Characteristics Ta = 25C Item Input voltage Symbol VIH Ta = -40 to +85C Max -- -- -- 0.5 1.35 1.8 -- -- -- -- -- 0.1 0.1 0.1 0.33 0.33 1.0 40 A A I OL = 4 mA I OL = 5.2 mA Vin = VCC or GND Vin = VCC or GND, Iout = 0 A V I OH = -4 mA I OH = -5.2 mA Vin = VIH or VIL I OL = 20 A V Vin = VIH or VIL I OH = -20 A V Unit V Test Conditions VCC (V) Min Typ Max Min 2.0 4.5 6.0 1.5 -- 3.15 -- 4.2 -- -- -- -- -- -- -- -- -- -- 0.5 1.5 3.15 4.2 -- VIL 2.0 4.5 6.0 1.35 -- 1.8 -- 1.9 4.4 5.9 4.13 5.63 -- -- -- Output voltage VOH 2.0 4.5 6.0 4.5 6.0 1.9 2.0 -- 4.4 4.5 -- 5.9 6.0 -- 4.18 -- 5.68 -- -- -- -- -- -- -- -- -- -- VOL 2.0 4.5 6.0 4.5 6.0 0.0 0.1 0.0 0.1 0.0 0.1 -- -- -- -- 0.26 -- 0.26 -- 0.1 -- 4.0 -- Input current Quiescent supply current Iin I CC 6.0 6.0 4 HD74HC149 AC Characteristics (CL = 50 pF, Input tr = tf = 6 ns) Ta = 25C Item Symbol Ta = -40 to +85C Max 175 35 30 195 39 33 95 19 16 10 pF ns ns E to Y, P Unit ns Test Conditions 0 - 7 to Y, P VCC (V) Min Typ Max Min 2.0 4.5 6.0 -- -- -- -- -- -- -- -- -- -- -- 16 -- -- 13 -- -- 5 -- 5 140 -- 28 24 -- -- Propagation delay t PLH time t PHL t PLH t PHL 2.0 4.5 6.0 155 -- 31 26 75 15 13 10 -- -- -- -- -- -- Output rise/fall time t TLH t THL 2.0 4.5 6.0 Input capacitance Cin -- 5 Unit: mm 24.50 25.40 Max 20 11 7.00 Max 6.30 1 0.89 1.27 Max 10 1.30 2.54 Min 5.08 Max 7.62 0.51 Min 2.54 0.25 0.48 0.10 0.25 - 0.05 0 - 15 + 0.11 Hitachi Code JEDEC EIAJ Weight (reference value) DP-20N -- Conforms 1.26 g Unit: mm 12.6 13 Max 20 11 1 10 5.5 0.80 Max 2.20 Max *0.22 0.05 0.20 0.04 0.20 7.80 + 0.30 - 1.15 0 - 8 0.70 0.20 1.27 *0.42 0.08 0.40 0.06 0.12 M *Dimension including the plating thickness Base material dimension 0.10 0.10 0.15 Hitachi Code JEDEC EIAJ Weight (reference value) FP-20DA -- Conforms 0.31 g Unit: mm 12.8 13.2 Max 20 11 7.50 1 0.935 Max 10 2.65 Max *0.27 0.05 0.25 0.04 0.25 10.40 + 0.40 - 1.45 0.20 0.10 0 - 8 0.57 0.70 + 0.30 - 1.27 *0.42 0.08 0.40 0.06 0.15 0.12 M Hitachi Code JEDEC EIAJ Weight (reference value) FP-20DB Conforms -- 0.52 g *Dimension including the plating thickness Base material dimension Cautions 1. Hitachi neither warrants nor grants licenses of any rights of Hitachi's or any third party's patent, copyright, trademark, or other intellectual property rights for information contained in this document. Hitachi bears no responsibility for problems that may arise with third party's rights, including intellectual property rights, in connection with use of the information contained in this document. 2. Products and product specifications may be subject to change without notice. Confirm that you have received the latest product standards or specifications before final design, purchase or use. 3. Hitachi makes every attempt to ensure that its products are of high quality and reliability. However, contact Hitachi's sales office before using the product in an application that demands especially high quality and reliability or where its failure or malfunction may directly threaten human life or cause risk of bodily injury, such as aerospace, aeronautics, nuclear power, combustion control, transportation, traffic, safety equipment or medical equipment for life support. 4. Design your application so that the product is used within the ranges guaranteed by Hitachi particularly for maximum rating, operating supply voltage range, heat radiation characteristics, installation conditions and other characteristics. Hitachi bears no responsibility for failure or damage when used beyond the guaranteed ranges. Even within the guaranteed ranges, consider normally foreseeable failure rates or failure modes in semiconductor devices and employ systemic measures such as failsafes, so that the equipment incorporating Hitachi product does not cause bodily injury, fire or other consequential damage due to operation of the Hitachi product. 5. This product is not designed to be radiation resistant. 6. No one is permitted to reproduce or duplicate, in any form, the whole or part of this document without written approval from Hitachi. 7. Contact Hitachi's sales office for any questions regarding this document or Hitachi semiconductor products. Hitachi, Ltd. Semiconductor & Integrated Circuits. Nippon Bldg., 2-6-2, Ohte-machi, Chiyoda-ku, Tokyo 100-0004, Japan Tel: Tokyo (03) 3270-2111 Fax: (03) 3270-5109 URL NorthAmerica : http:semiconductor.hitachi.com/ Europe : http://www.hitachi-eu.com/hel/ecg Asia (Singapore) : http://www.has.hitachi.com.sg/grp3/sicd/index.htm Asia (Taiwan) : http://www.hitachi.com.tw/E/Product/SICD_Frame.htm Asia (HongKong) : http://www.hitachi.com.hk/eng/bo/grp3/index.htm Japan : http://www.hitachi.co.jp/Sicd/indx.htm For further information write to: Hitachi Semiconductor (America) Inc. 179 East Tasman Drive, San Jose,CA 95134 Tel: <1> (408) 433-1990 Fax: <1>(408) 433-0223 Hitachi Europe GmbH Electronic components Group Dornacher Strae 3 D-85622 Feldkirchen, Munich Germany Tel: <49> (89) 9 9180-0 Fax: <49> (89) 9 29 30 00 Hitachi Europe Ltd. Electronic Components Group. Whitebrook Park Lower Cookham Road Maidenhead Berkshire SL6 8YA, United Kingdom Tel: <44> (1628) 585000 Fax: <44> (1628) 778322 Hitachi Asia Pte. Ltd. 16 Collyer Quay #20-00 Hitachi Tower Singapore 049318 Tel: 535-2100 Fax: 535-1533 Hitachi Asia Ltd. Taipei Branch Office 3F, Hung Kuo Building. No.167, Tun-Hwa North Road, Taipei (105) Tel: <886> (2) 2718-3666 Fax: <886> (2) 2718-8180 Hitachi Asia (Hong Kong) Ltd. Group III (Electronic Components) 7/F., North Tower, World Finance Centre, Harbour City, Canton Road, Tsim Sha Tsui, Kowloon, Hong Kong Tel: <852> (2) 735 9218 Fax: <852> (2) 730 0281 Telex: 40815 HITEC HX Copyright ' Hitachi, Ltd., 1999. All rights reserved. Printed in Japan. |
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