High-Side Current Sense Amplifiers

What is High-Side Current Sensing?

High-Side Current Sensing (HSCS) connects the sensing resistor between the power supply and load. The sensed voltage signal is amplified by the subsequent op amp circuits to get measurable output.

High-Side-Current-Sensing.PNG

Advantages:

  • Eliminates ground disturbance
  • Load connects system ground directly
  • Detects the high load current caused by accidental shorts

Disadvantages:

  • Must be able to handle very high and dynamic common mode input voltages
  • Complexity and higher costs
  • High VDD parts

In a single-supply configuration, the most important aspects of HSCS are:

  • The Common Mode Voltage (VCM) range of the difference amplifier must be wide enough to withstand high common mode input voltages
  • The difference amplifier’s ability to reject dynamic common mode input voltages

Application Example

Motor Control

  • HSCS amplifiers are commonly used within motor control applications, including: automotive, industrial, and medical.
hscs-motor-control-application.png

Automotive

  • Power doors, locks, roofs, and mirrors, electric seats, power steering, and oil pumps
  • Increasing global fuel economy rules resulting in higher efficiency
  • Over 600 million DC motors in traditional light vehicles in 2018
Automotive-Actuator.png

Consumer, Industrial, Medical, Consumer, Computing/Telecom

  • Small appliances, HVAC, toys, and set-top boxes
  • Servos, positioning actuators (factory automation/process control), and building automation
  • Surgical tools (staplers, orthopedic drills, etc.), insulin pumps, and oxygen concentrators

What is MCP6C02/4?

  • Amplifiers designed to measure the current through a small resistor
  • Provide an amplified output voltage proportional to the measured current
  • Input voltages from 3 V up to 65 V (MCP6C02), 3 V up to 52 V (MCP6C04), and output from 2 V to 5.5 V
  • Reference pin allows for both unidirectional or bidirectional current measurement

This video discusses the use of amplifiers in shunt-based current sensing applications as well as the pros and cons of high-side and low-side monitoring.

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