3 Introduction of IEC/UL 60730-1/60335-1 Standards

UL 60335 is a safety standard designed for household and similar electrical appliances and developed by Underwriters Laboratories (UL), a reputable American electrical safety certification organization. The primary goal of this standard is to ensure the safety and well-being of users. UL 60335 is a globally recognized standard that many countries and regions adopt or refer to for the safety review and certification of electrical products.

UL 60335 electrical standard encompasses a range of safety requirements for electrical products, including but not limited to product structure and materials, electrical connections and insulation, heating and mechanical strength, temperature, and electrical parameters. This application note primarily focuses on the safety requirements related to MCU. The reference appendix R in UL 60335-1 lists the software evaluation requirements, with the majority of MCU control failure self-test requirements almost entirely based on IEC 60730-1, including the regulations referenced for each safety requirement. Therefore, the following discussion is about IEC 60730-1.

IEC 60730 is an internationally recognized standard established by the International Electrotechnical Commission (IEC), which specifies safety and functional requirements for automatic electrical controls. This standard primarily applies to household and similar appliances and electronic devices, including but not limited to household appliances, lighting equipment, air conditioning systems, and power tools. Analyzing the IEC 60730 standard from a professional standpoint, the following aspects can be evaluated:

1. Device Safety Requirements: IEC 60730 imposes clear safety requirements on automatic control devices, encompassing electrical safety, mechanical safety, fire safety, and other aspects. These requirements aim to make sure that devices do not pose harm to humans or the environment during regular operation.
2. Device Functionality Requirements: IEC 60730 also defines requirements for the functional performance of automatic control devices, including measurement, detection, control, and regulation. These requirements ensure that devices can meet user needs and exhibit stable and reliable performance.
3. Device Reliability Requirements: IEC 60730 sets reliability requirements for automatic control devices, encompassing device lifespan, fault diagnosis, fault recovery, and other aspects. These requirements make sure that devices do not frequently malfunction during long-term use and can effectively handle faults in a timely manner.
4. Device Marking and Labeling Requirements: IEC 60730 also regulates the marking and labeling requirements for automatic control devices, including device model, serial number, safety-related information, and so forth. These requirements help users utilize devices correctly and promptly understand the safety performance.

In conclusion, the IEC 60730 standard provides detailed requirements from a professional standpoint for the safety, functional performance, reliability, marking, and labeling of automatic control devices. The standard helps make sure that devices can achieve the expected safety and functional performance during the design, manufacturing, usage, and maintenance processes. This standard plays a crucial guiding role in the automatic electrical control equipment industry, providing manufacturers, designers, and users with a shared benchmark to adhere to.

IEC 60730 defines 3 classes:

1. Class A: functions such as room thermostats, humidity controls, lighting controls, timers and switches. These are distinguished by not being relied upon for the safety of the equipment.
2. Class B: functions such as thermal cutoffs are intended to prevent unsafe operation of appliances such as washing machines, dishwashers, dryers, refrigerators, freezers, and cookers or stoves.
3. Class C: functions are intended to prevent special hazards such as explosions. These include automatic burner controls and thermal cutouts for closed, unvented water heaters.

Safety requirements in household appliance applications primarily revolve around Class B. As a result, subsequent standard requirements and testing methods are introduced and analyzed based on Class B.

IEC 60730-1 has outlined specific specifications for various types of commodities, with requirements for electronic control devices listed in reference Appendix H. In Appendix H. H.11.12.7 provides detailed descriptions of components that must be tested, with the specific tests depending on the software classification. The types of faults and testing methods for each component are listed in Table H.1. Table 3-1 presents all the items that need to be considered for MCU in appliances according to the IEC-60730-1 Class B requirements.

Items 1, 3, 4, 5, and 7 mainly pertain to the functional aspects of the MCU, while items 2 and 6 correspond to the test requirements for application functionality. Regarding the fault detection for application functionality, it is necessary to add corresponding test code based on the software structure and specific requirements of the certification agencies. For the MCU-related fault detection, TI's C2000 series MCU provides the principles and examples for all the relevant test requirements.

In conclusion, by incorporating the required C2000 self-test libraries into the application program, most appliances can quickly meet the Class B test requirements of IEC/UL 60730-1, also satisfying those of IEC/UL 60335-1 safety certification.