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ESKISEHIR OSMANGAZI UNIVERSITY
ELECTRICAL AND ELECTRONICS ENGINEERING
2020 - 2021 SPRING SEMESTER
DIGITAL SYSTEMS LABORATORY
EXPERIMENT 6
DIGITAL TO ANALOG CONVERSION
MERVE AKSU, 151220184081
GROUP II - A
ESKISEHIR OSMANGAZI UNIVERSITY
ELECTRICAL AND ELECTRONICS ENGINEERING
EXPERIMENT 6 REPORT
OBJECTIVES
- Understanding how and for what purpose DAC080 8 is used.
- Learning how to convert digital input to analog output. INTRODUCTION DAC0808 is a D / A converter IC and used to convert 8-bit digital data input to analog signal output. The power supply currents of the DAC0808 are independent of bit codes and exhibit essentially constant device characteristics over the entire supply voltage range. DAC0808 IC is used in applications where digital to analog conversion is required. The chip was popular ten years ago and its applications were many, but now there are many modern ICs that can perform DAC with higher resolution, speed and efficiency, so this device is mainly used for reference and starting applications and nothing more. DAC enabled microcontroller or serial interface DAC IC is currently preferred for advanced applications. Pin Name Description 1 NC No connection 2 GND Ground 3 VEE Negative power supply 4 IO Output signal pin 5 A1 Digital input bit 1 (Most Significant Bit) 6 A2 Digital input bit 2 7 A3 Digital input bit 3 8 A4 Digital input bit 4 9 A5 Digital input bit 5 10 A6 Digital input bit 6 11 A7 Digital input bit 7 12 A8 Digital input bit 8 (Least Significant Bit) 13 VCC Positive power supply 14 VREF+ Positive reference voltage 15 VREF- Negative reference voltage 16 COMPENSATION Compensation capacitor pin
3 - Set Vref=5 V. 4 - By using your OSCILLOSCOPE, measure the corresponding output voltages for the digital input values given in table 1. 5 - Set Vref=10 V and repeat Step 4.
Figure 1 Table 1. DIGITAL INPUT ANALOG OUTPUT BINARY VREF=10V VREF=5V 0 0 0 0 0 0 0 0 0.00 0. 1 1 1 1 1 1 1 1 - 11.7 - 11. 1 0 0 0 0 0 0 0 - 11.6 - 10.0 0 0 1 0 0 0 0 0 0 - 6.25 - 5.0 0 0 0 1 0 0 0 0 0 - 3.12 - 2.5 0 0 0 0 0 0 0 0 1 - 0.09 - 0. 0 0 1 1 0 0 1 1 - 4.98 - 3. 0 1 0 1 0 0 0 1 - 7.91 - 6. 1 0 0 0 0 0 0 1 - 11.6 - 10. 0 0 0 1 0 0 0 0 - 1.56 - 1. Note: You will fill the table with analog outputs firstly. And you will add your simulation program output photos for the cells containing (Add photo) text.
For Vref=5V, DI=0 0 0 0 0 0 1. For Vref=5V, DI=0 1 0 1 0 0 0 1.
For Vref=10V, DI= 0 0 1 1 0 0 1 1. For Vref=10V, DI= 1 0 0 0 0 0 0 1.
DISCUSSION AND CONCLUSIONS
In this experiment, it was observed how dac0808 converts digital input to analog output in the proteus environment. The circuit in the Figure 1. has been set up and power has been connected to the A pins with the switch. DC voltmeter was used to measure the output voltage. Procedure 1- The circuit given in Figure 1 is set up. Selected R14=R15=RL=4.7 Kohm, C=100 nF. Also digital inputs to the switches on the training set are connected. Procedure 2- VEE is set - 15V. Procedure 3- Vref is set 5V. Procedure 4- By using DC voltmeter, the corresponding output voltages for the digital input values given in table 1 is measured and reflected to it. Procedure 5- Vref is set 10V and repeated Step 4. Thus, it was understood which analog signal the inputs entered together with the reference voltage value correspond to. However, slight differences were observed between the actual experimental environment and the measurements in the proteus environment. this was assumed to be because measurement with a real circuit may yield results different from ideal. Sometimes it happens that ideal results are not obtained in the proteus, but it is mostly ideal. In addition, it was observed that the 1st, 2nd and 13th pins of dac0808 in the proteus were absent. The 1st pin should be ignored since it is NC, no connection pin, and nothing will be connected anyway. Since the 2nd and 13th pins are GND and VCC pins, these pins are ignored in the proteus, because a crowded circuit is not required and for convenience, so these values are already given.
