ee3954_fall13_10_adc

8756v 100 0234v 000 49876v 111 11v 001 32v 101 adc10

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Unformatted text preview: t; 23 = 8 levels => 7 thresholds (5v/8 = 0.625) ADC.9 ADC 3-bit Example Examples: Examples: Analog Input Voltage: Digital Output: 2.8756V 100 -0.234V 000 4.9876V 111 1.1V 001 3.2V 101 ADC.10 ADC The PIC16F877 Microcontroller •  10-bits: –  210 = 1024 levels => 1023 thresholds –  Resolution = 5V/1024 = 0.0048828125 V –  Thresholds: •  0.0048828125 V •  0.009765625 V •  0.0146484375 V •  Etc. ADC.11 ADC Implementation: Parallel-Encoded or Flash ADC Vref = 5V 4.375V 3.750V Example: 3-bit ADC Vin I7 I6 3.125V I5 O0 2.500V I4 1.875V I3 1.250V 0.625V Priority Encoder O1 Digital Value out O2 I2 I1 I0 ADC.12 Digital Logic – Revisited (?/) Priority Encoder I7 I6 I5 I4 I3 I2 I1 I0 O2 O1 O0 H H H H H H H L H H H H H H H H H L X H H L H H H H H L X X H L H H H H H L X X X H L L H H H L X X X X L H H H H L X X X X X L H L H L X X X X X X L L H L X X X X X X X L L L Note: if one uses active low, LLH = 110 ADC.13 ADC Implementation: Parallel-Encoded or Flash ADC Vref = 5V 4....
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