Purpose: Converts current flow into a measurable voltage drop.

Working Principle: Uses Ohm's Law (V = I × R); measures small voltage across precision resistor to calculate current.

Key Features:

• Low resistance value (mΩ to Ω range)
• High precision and low temperature coefficient (TCR)
• Four-terminal (Kelvin) design to eliminate lead resistance errors
• Power ratings from 1/4W up to several watts

Common Applications:

• Battery management systems (BMS)
• Motor control
• Power supplies
• Overcurrent protection circuits

Typical Materials: Manganin, Tin Oxide, or metal foil for stability.

Considerations:

• Minimize power loss (I²R heating)
• Amplification often needed (use instrumentation amplifier)
• PCB layout: keep sense traces short, use Kelvin connection