SBAA666 February   2025 AMC0106M05 , AMC0106M25

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction
  5. 2Design Challenges
  6. 3Design Approach
    1. 3.1 AMC0106Mxx Functionally Isolated Modulators
    2. 3.2 Circuit Design and Layout
    3. 3.3 Sinc3 Filter Design
  7. 4Test and Validation
    1. 4.1 Test Setup
    2. 4.2 Digital Interface
    3. 4.3 DC Accuracy, Noise, and Effective Number of Bits
    4. 4.4 PWM Rejection
      1. 4.4.1 DC Phase Current Measurement Over One PWM Cycle
      2. 4.4.2 AC Phase Current Measurement at 100kHz PWM
    5. 4.5 Bootstrap Supply Validation and AVDD Ripple Rejection Tests
      1. 4.5.1 LMG2100R044 Bootstrap Supply With Low Voltage-Ripple
      2. 4.5.2 Discrete Bootstrap Supply With High Voltage-Ripple
  8. 5Summary
  9. 6References

Abstract

This application note introduces the newly released AMC0106M05 and AMC0106M25 functionally isolated modulators. The M05 variant supports a ±50mV, the M25 variant a ±250mV linear input range. Both devices come in a small, lead-less package. The AMC0106Mxx devices enable the design of an accurate and reliable, shunt-based current-sensing subsystem for three-phase inverters with a small form-factor. Typical applications are servo drives, and collaborative or humanoid robots powered from sub-60V power supplies. A circuit design and layout example for a 48V 3-phase GaN inverter with boot bootstrap supply with a ±50A linear current range is presented. The design is based on the AMC0106M05 variant and 1mΩ shunt. Test results are presented showing that a measurement resolution up to 14 effective number of bits (ENOB) is achieved. Phase current measurement is not affected by PWM switching, validating the high immunity against common-mode transients. And finally, this has shown that ripple voltage caused by the bootstrap supply has no effect on the phase current measurement for a wide range of PWM duty cycles.