3.6 ZCD - Zero-Cross Detector

The Zero-Cross Detector (ZCD) detects when an alternating voltage crosses through a threshold voltage near the ground potential. The ZCD can be used when monitoring an alternating waveform for, but not limited to, the following purposes:
  • Period Measurement
  • Accurate Long-Term Time Measurement
  • Dimmer Phase-Delayed Drive
  • Low-EMI Cycle Switching

Figure 3-2. AVR® Dx - ZCD Block Diagram

To detect zero-crossing, it requires only a current limiting resistor in series (RSERIES), thus simplifying the design.

Note: For code examples and details about using the ZCD peripheral, refer to TB3233 - Using ZCD to Implement Special Functions.