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Digital to Analog Converter DAC

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**1. **Digital to Analog Converter (DAC) Trayvon Leslie
Orlando Carreon
Zack Sosebee

**2. **Outline Overview
Choosing a DAC
Specifications
Resolution
Speed
Linearity
Settling Time
Reference Voltages
Errors
Errors
Types of DAC
Binary Weighted Resistor
R-2R Ladder
Multiplier DAC
Non-Multiplier DAC
Applications
References

**3. **Overview Digital to Analog Converter (DAC)
A digital to analog converter (DAC) is a device that converts digital numbers (binary) into an analog voltage, current, or electric charge output.

**4. **Overview Typically generates a piecewise continuous function
Step Functions
The function is continuous between each of the open intervalsTypically generates a piecewise continuous function
Step Functions
The function is continuous between each of the open intervals

**5. **Overview Normally a linear function
Normally a linear function

**6. **Overview

**7. **Overview AD 7224
8-Bit Voltage Output
R-2R
Output AmplifierAD 7224
8-Bit Voltage Output
R-2R
Output Amplifier

**8. **Overview 8 input pins
Reference Voltage
Variable Resistors
Helps to meet the output signal requirements
Helps to adjust input signal
Offset: Decreasing the offset Decreases the Output Voltage
Gain:8 input pins
Reference Voltage
Variable Resistors
Helps to meet the output signal requirements
Helps to adjust input signal
Offset: Decreasing the offset Decreases the Output Voltage
Gain:

**9. **Choosing a DAC When it comes to your project…
There are 6 main specification for choosing your DACWhen it comes to your project…
There are 6 main specification for choosing your DAC

**10. **Specifications The out of the DAC is largely determined by the reference voltage
Usually changes with the types of DAC
Multiplier: (Internal Reference)
Fixed Reference Voltage
Less Error
Non-Multiplier: (External Reference)
Multiplies binary functions
Scales ContinuousThe out of the DAC is largely determined by the reference voltage
Usually changes with the types of DAC
Multiplier: (Internal Reference)
Fixed Reference Voltage
Less Error
Non-Multiplier: (External Reference)
Multiplies binary functions
Scales Continuous

**11. **Specifications Similar to the ADC
Will be shown from the linear specifications
Function of the Reference Voltage and the Number of Bits
Increasing the bits decreases the resolution (finer)
Number of bits representing an analog signal -- generally ranging from 6 to 24. The higher the number of
bits, the higher the resolution of the converter. Generally more accurate too.Similar to the ADC
Will be shown from the linear specifications
Function of the Reference Voltage and the Number of Bits
Increasing the bits decreases the resolution (finer)
Number of bits representing an analog signal -- generally ranging from 6 to 24. The higher the number of
bits, the higher the resolution of the converter. Generally more accurate too.

**12. **Specifications Depending on the binary number that
How well the device's actual performance across a specified operating range approximates a straight line.
Maximum deviation of actual performance relative to a straight line, located such that it minimizes the maximum deviation
Depending on the binary number that
How well the device's actual performance across a specified operating range approximates a straight line.
Maximum deviation of actual performance relative to a straight line, located such that it minimizes the maximum deviation

**13. **Specifications The rate at which the input digital or binary number are cycled through the DAC
The number of conversions per second the DAC is producing.
Clock speed: the speed at which the CPU operates.The rate at which the input digital or binary number are cycled through the DAC
The number of conversions per second the DAC is producing.
Clock speed: the speed at which the CPU operates.

**14. **Specifications Ideally
Usually updated at uniform sampling intervals
Each number latched in sequence
The time required for the output to reach and remain within a specified error band about its final value,
measured from the start of the output transition.Ideally
Usually updated at uniform sampling intervals
Each number latched in sequence
The time required for the output to reach and remain within a specified error band about its final value,
measured from the start of the output transition.

**15. **Specifications

**16. **Errors Gain Error Deviation in the slope of the ideal curve and with respect to the actual DAC output

**17. **Errors Offset Error
Occurs when there is an offset in the output voltage in reference to the ideal output.

**18. **Errors Full Scale Error

**19. **Errors Non-Linearity Differential Non-Linearity: Voltage step size differences vary as digital input increases. Ideally each step should be equivalent.

**20. **Errors Non-Linearity Integral Non-Linearity: Occurs when the output voltage is non linear. Basically an inability to adhere to the ideal slope.

**21. **Errors Non-Monotonic Output Error
Occurs when the an increase in digital input results in a lower output voltage.

**22. **Errors Settling Time and Overshoot

**23. **Errors Settling Time and Overshoot

**24. **Errors Resolution
Inherent errors associated with the resolution
More Bits = Less Error and Greater Resolution
Less Bits = More Error and Less Resolution

**25. **Errors Resolution Poor Resolution (1 Bit)

**26. **Errors Resolution Better Resolution (3 Bit)

**27. **Types of DAC

**28. **Types of DAC

**29. **Types of DAC

**30. **Types of DAC

**31. **Types of DAC

**32. **Types of DAC

**33. **Types of DAC

**34. **Types of DAC

**35. **Types of DAC

**37. **Types of DAC

**38. **Types of DAC

**39. **Types of DAC

**40. **Applications

**41. **Applications

**42. **Applications

**43. **Applications

**44. **Applications

**45. **Applications

**46. **References http://en.wikipedia.org/wiki/Digital-to-analog_converter
Alciatore, “Introduction to Mechatronics and Measurement Systems,” McGraw-Hill, 2003
Horowitz and Hill, “The Art of Electronics,” Cambridge University Press, 2nd Ed. 1995
http://products.analog.com/products/info.asp?product=AD7224
http://courses.washington.edu/jbcallis/lectures/C464_Lec5_Sp-02.pdf
http://www.eecg.toronto.edu/~kphang/ece1371/chap11_slides.pdf
Past student lectures

**47. **Questions