數(shù)字電路與邏輯設(shè)計英文教學(xué)ppt(編輯修改稿)

　

【文章內(nèi)容簡介】 e 0101, 0110, 0011, and 0010. Describe the output. All lines are HIGH except for one active output, which is LOW. The active outputs are 5, 6, 3, and 2 in that order. 169。 2022 Pearson Education, Upper Saddle River, NJ 07458. All Rights Reserved Floyd, Digital Fundamentals, 10th ed Summary BCD Decoder/Driver Another useful decoder is the 74LS47. This is a BCDtoseven segment display with active LOW outputs. The ag outputs are designed for much higher current than most devices (hence the word driver in the name). abcdefg1248( 1 6 )( 4 )( 1 3 )( 1 2 )( 1 1 )( 1 0 )( 9 )( 1 5 )( 1 4 )( 1 )( 2 )( 6 )( 7 )( 3 )( 5 )( 8 )BCD inputs Outputs to seven segment device GND VCC BCD/7seg BI/RBO BI/RBO LT RBI LT RBI 74LS47 169。 2022 Pearson Education, Upper Saddle River, NJ 07458. All Rights Reserved Floyd, Digital Fundamentals, 10th ed Summary BCD Decoder/Driver Here the 7447A is an connected to an LED seven segment display. Notice the current limiting resistors, required to prevent overdriving the LED display. VCCGND+ V+ VR 39。 s =330 WabcdefgabcdefgM A N 7274L S 47LTBI/ RBORBI k W11223, 9, 143456778891010111112 1313141516BCD / 7 s e gBCDi npu tDCBA169。 2022 Pearson Education, Upper Saddle River, NJ 07458. All Rights Reserved Floyd, Digital Fundamentals, 10th ed Summary BCD Decoder/Driver abcdefg B I / R B O0 0 0 08 4 2 1R B I L T07 4 L S 4 7abcdefg B I / R B O0 0 0 08 4 2 1R B I L T07 4 L S 4 7abcdefg B I / R B O0 0 1 18 4 2 1R B I L T07 4 L S 4 7abcdefg B I / R B O0 0 0 08 4 2 1R B I L T17 4 L S 4 7Blanked Blanked The 74LS47 features leading zero suppression, which blanks unnecessary leading zeros but keeps significant zeros as illustrated here. The BI/RBO output is connected to the RBI input of the next decoder. Depending on the display type, current limiting resistors may be required. 169。 2022 Pearson Education, Upper Saddle River, NJ 07458. All Rights Reserved Floyd, Digital Fundamentals, 10th ed Summary BCD Decoder/Driver Blanked Blanked abcdefg B I / R B O0 1 0 18 4 2 1R B I L T7 4 L S 4 71abcdefg B I / R B O0 1 1 18 4 2 1R B I L T7 4 L S 4 7abcdefg B I / R B O0 0 0 08 4 2 1R B I L T7 4 L S 4 70abcdefg B I / R B O0 0 0 08 4 2 1R B I L T7 4 L S 4 70Decimal point Trailing zero suppression blanks unnecessary trailing zeros to the right of the decimal point as illustrated here. The RBI input is connected to the BI/RBO output of the following decoder. 169。 2022 Pearson Education, Upper Saddle River, NJ 07458. All Rights Reserved Floyd, Digital Fundamentals, 10th ed Summary Encoders An encoder accepts an active logic level on one of its inputs and converts it to a coded output, such as BCD or binary. The decimal to BCD is an encoder with an input for each of the ten decimal digits and four outputs that represent the BCD code for the active digit. The basic logic diagram is shown. There is no zero input because the outputs are all LOW when the input is zero. A1 A0 A2 A3 1 2 3 4 5 6 7 8 9 169。 2022 Pearson Education, Upper Saddle River, NJ 07458. All Rights Reserved Floyd, Digital Fundamentals, 10th ed Summary Encoders A1 A0 A2 A3 Show how the decimaltoBCD encoder converts the decimal number 3 into a BCD 0011. The top two OR gates have ones as indicated with the red lines. Thus the output is 0111. 1 2 3 4 5 6 7 8 9 0 0 0 0 0 0 0 0 1 0 0 1 1 169。 2022 Pearson Education, Upper Saddle River, NJ 07458. All Rights Reserved Floyd, Digital Fundamentals, 10th ed Summary Encoders The 74HC147 is an example of an IC encoder. It is has ten activeLOW inputs and converts the active input to an activeLOW BCD output. This device is offers additional flexibility in that it is a priority encoder. This means that if more than one input is active, the one with the highest order decimal digit will be active. Decimal input BCD output 1248( 1 6 )( 1 1 )( 1 2 )( 1 3 )( 1 )( 2 )( 4 )( 3 )( 5 )( 9 )( 7 )( 6 )( 1 4 )( 8 )12345678( 1 0 )9GND VCC HPRI/BCD 74HC147 The next slide shows an application … 169。 2022 Pearson Education, Upper Saddle River, NJ 07458. All Rights Reserved Floyd, Digital Fundamentals, 10th ed Summary Encoders VCC BCD plement of key press 12345678912489876532104R7R8R9R4R5R6R1R2R3R0Ke