With the demand for smart home devices and IoT applications increasing there is a need for added communication functionality (i.e. Wi-Fi) to home appliances, according to ROHM. These devices need to remain ON to maintain communication so, as a result, manufacturers are required to reduce standby power consumption even more to around 0.5W. This calls for lower standby power consumption by the motor and power supply blocks along with innovative new technologies.
Many appliances require a zero cross detection circuit for detecting the 0V point (zero cross point) of the AC waveform in order to provide efficient control of both motors and MCUs. However, in terms of power consumption, conventional zero cross detection circuits use a photocoupler that accounts for nearly half of the standby power of the entire system.
In response, ROHM has developed the first integrated zero cross detection solution for power supplies in the home appliance sector. The integrated zero cross detection IC provides designers a turn-key zero cross detector without the need for a complex design using discrete components.
In addition, this integrated solution does not use a photo-coupler typically used in other solutions, and, is able to further reduces standby current consumption and increase long-term reliability.
The BM1ZxxxFJ series reduces standby power consumption of the zero cross circuit to just 0.01W while continuously powering the system. Also, the error in delay time (which varies depending on the AC voltage) that exists with conventional photocoupler-equipped zero cross detection circuits is limited to ±50µs or less. This allows for the efficient drive of motors – even with the different AC supply voltages used in various countries and regions – as well as MCUs. At the same time, eliminating the need for a photocoupler contributes to greater application reliability by reducing risks related to age-based degradation.
Both pulse and edge waveforms used in home appliance specifications are supported by the BM1ZxxxFJ series, eliminating the need for software changes when replacing conventional zero cross detection circuits. ROHM is offering six models to ensure compatibility with a wide range of home appliances.
An integrated zero cross detection IC development board is also available, integrating a power supply for driving ROHM’s integrated zero cross detection IC and facilitating device evaluation. This board has been designed to simplify the decision-making process for designers when considering replacement of existing circuits using a photocoupler.