Binary-weighted-input DAC resistor current A binary-weighted DAC uses an input resistor of 100 kΩ tied to a 5 V source for the MSB branch. What current flows through this 100 kΩ resistor when it is connected to 5 V (assume ideal conditions)?

Introduction / Context:
Binary-weighted DACs scale currents or voltages by powers of two. Understanding the basic Ohm’s law relationship for the input branch resistors helps verify expected current magnitudes and check component selections for headroom and op-amp compliance.

Given Data / Assumptions:

• Resistor R = 100 kΩ connected to a 5 V source.
• Assume ideal behavior (no additional series elements).
• Goal: compute current I through the resistor.

Concept / Approach:

Use Ohm’s law: I = V / R. Substitute the given values to obtain the current in amperes and convert to microamperes for a neat engineering unit.

Step-by-Step Solution:

Verification / Alternative check:

Back-calculate voltage: 50 µA * 100 kΩ = 5 V, confirming consistency. This current is typical for DAC ladder branches and is well below milliamp ranges.

Why Other Options Are Wrong:

50 mA, 5 mA, and 500 µA are orders of magnitude too large for 100 kΩ at 5 V.

Common Pitfalls:

Mistaking kΩ for Ω in calculation; mixing microamp and milliamp conversions; ignoring tolerance and switch on-resistance that slightly alter real currents.

Final Answer:

50 µA