1. ©F.M. Rietti Components Fundamentals

2. ©F.M. Rietti LM-18 Computer Science SSI Embedded Systems I 2 Active Components (cont) Comparator –if V2 > V1 the output is driven to the positive supply voltage and if V2 < V1 it is driven to the negative supply voltage.

3. ©F.M. Rietti LM-18 Computer Science SSI Embedded Systems I 3 Active Components (Cont) Oscillators –Devices producing a periodic signal –Digital Electronics use “square wave” oscillators Flip Flop based Schmitt trigger (follow this link)Schmitt trigger

4. ©F.M. Rietti LM-18 Computer Science SSI Embedded Systems I 4 Active Components (cont) Summing Amplifier –For the summing amplifier by the current rule the non-inverting input is a virtual ground. Then the current into A must be zero. This requires V1/R1 + V2/R2 = - Vout/R3 but R1=R3=R3 then Vout=-(V1+V2)summing amplifiercurrent rule

5. ©F.M. Rietti LM-18 Computer Science SSI Embedded Systems I 5 Active Components (cont) Flip Flop "Flip-flop" is the common name given to two-state devices which offer basic memory for sequential logic operations. Flip- flops are heavily used for digital data storage and transfer and are commonly used in banks called "registers" for the storage of binary numerical data.Flip Flopsequential logic

6. ©F.M. Rietti LM-18 Computer Science SSI Embedded Systems I 6 Active Components (cont) Counters A binary counter can be constructed from J-K flip- flops by taking the output of one cell to the clock input of the next. The J and K inputs of each flip-flop are set to 1 to produce a toggle at each cycle of the clock input. For each two toggles of the first cell, a toggle is produced in the second cell, and so on down to the fourth cell. J-K flip- flops

7. ©F.M. Rietti LM-18 Computer Science SSI Embedded Systems I 7 Active Components (cont) 12 bit summing amplifier computing

8. ©F.M. Rietti LM-18 Computer Science SSI Embedded Systems I 8 Active Components (cont) Summing Amplifier DAC –Limits Precision depend from resistor tolerance Precision influenced from final impedance Vout-Ground Temperature –Solved by IC with more complex circuits & Embedded Systems boards perform DAC operation, interfacing DAC IC –Further info (Hyper Physics Site)(Hyper Physics Site) –DAC IC panoramic (Texas Instruments Site)(Texas Instruments Site)

9. ©F.M. Rietti LM-18 Computer Science SSI Embedded Systems I 9 Active Components (cont) Analog to Digital Converter (ADC) –Digital Ramp ADC Conversion from analog to digital form inherently involves comparator action where the value of the analog voltage at some point in time is compared with some standard. A common way to do that is to apply the analog voltage to one terminal of a comparator and trigger a binary counter which drives a DAC. The output of the DAC is applied to the other terminal of the comparator. Since the output of the DAC is increasing with the counter, it will trigger the comparator at some point when its voltage exceeds the analog input. The transition of the comparator stops the binary counter, which at that point holds the digital value corresponding to the analog voltage.comparatorbinary counterDAC