DAC identification — The AD7524 is widely known as an 8-bit D/A converter that implements an R-2R ladder network. Evaluate this specification.
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ACorrect
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BIncorrect
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CTrue only for current-mode operation
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DDepends on supply ripple
Answer
Correct Answer: Correct
Explanation
Introduction / Context: Understanding common DAC architectures helps in selecting parts and interpreting datasheets. The AD7524 is a classic 8-bit multiplying DAC that uses an R-2R ladder to generate an output proportional to a reference. Recognizing its architecture aids in predicting behavior such as linearity, settling time, and output compliance.Given Data / Assumptions:
- Device: AD7524-class 8-bit DAC.
- Architecture: R-2R ladder network feeding a current output.
- External op-amp typically used to convert current to voltage (I-to-V).
Concept / Approach: R-2R ladders implement binary-weighted currents or voltages using only two resistor values, simplifying matching and scaling across bits. The AD7524 uses MOS switches to steer ladder currents relative to a reference, producing a code-proportional output that is then usually converted by an op-amp to a voltage. This matches the description in the statement.Step-by-Step Solution:
Identify the part family and resolution: 8 bits.Confirm internal topology: R and 2R resistors in a ladder with CMOS switches.Recognize output mode: current output (multiplying DAC), often needs an op-amp for Vout.Verification / Alternative check:
Reference typical application circuits: the AD7524 with an op-amp transimpedance stage is standard in textbooks and datasheets.Why Other Options Are Wrong:
Incorrect: Conflicts with established device descriptions.True only for current-mode operation: The architecture is R-2R regardless of the I-to-V stage used.Depends on supply ripple: Supply quality affects noise but not the core architecture.Common Pitfalls:
Assuming all DACs are voltage-output; many use current output with external amplifiers.Confusing R-2R with binary-weighted resistor DACs that require many values.Final Answer:
Correct