The Industry’s First Integrated Zero Cross Detection ICs from ROHM Semiconductor - Seite 2

Key Features

Developing a zero cross detection circuit without a photocoupler contributes to improved reliability and reduced power consumption in a variety of applications, including home appliances.

1. Breakthrough photocoupler-less zero cross detection circuit design minimizes application standby power consumption

Conventional zero cross detection circuits commonly utilize a photocoupler and transistor that accounts for nearly half of the standby power consumption of the entire application. This time, after analyzing hundreds of power supply patterns in different environments, ROHM was able to achieve an IC capable of detecting the zero cross without a photocoupler.

Along with reducing the number of parts, the new design delivers a standby power consumption close to zero (0.01W). And in motor applications it is possible to further decrease component count along with standby power consumption by eliminating the motor input voltage detection circuit. 

2. Contributes to improved reliability and efficiency in home appliances in a variety of countries and regions

Using a photocoupler involves risks that include performance degradation due to the deterioration in luminous intensity over time. Eliminating the photocoupler not only reduces this failure risk but also limits the delay time error, which can vary depending on the AC voltage, to ±50μs or less. This makes it possible to efficiently drive motors even with the different supply voltages (100-230V) used in various countries – as well as MCUs, which is difficult or impossible to achieve using conventional zero cross detection circuits.

3. Easily replace conventional zero cross detection circuits

ROHM’s new series supports the waveforms (pulse/edge) and circuit topologies (standard rectification/double rectification) utilized in conventional zero cross detection circuits, allowing users to easily replace standard zero cross detection circuits equipped with a photocoupler without requiring software changes.

4. Integrated voltage clamp function protects the downstream MCU

The BM1ZxxxFJ series is compatible with input voltages up to 600V and performs voltage division to output below the maximum rated voltage of MCU and drive standard MCUs up to 5V. A voltage clamp function is also included that ensures the input voltage does not exceed 4.8V, protecting the MCU even when abnormal voltages are generated in high voltage drive applications such as air conditioners.