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the IHB identification of each IC supports arbitration on the single-wire bus using the device ID time period (tID). HB1 has a tID of 40 µs, the tID for HB2 is 60 µs and the tID for HB3 is 80 µs. The system MCU is assigned a default tID of 160 µs, guaranteeing that it always wins bus arbitration.
Figure 4: BridgeSwitch status reporting combines single wire fault com- munication bus with device ID programming (green).
the safety approval process for product updates.
BridgeSwitch combines comprehensive internal fault protection functions with external system level monitoring and reporting via a bidirectional FAULT bus (Figure 3). Internal fault protection includes two-level thermal overload protection and cycle-by- cycle current for both FREDFETs. System level monitoring includes four undervoltage levels and one overvoltage level on the high-voltage (HV) DC bus, and external sensors such as a negative coefficient thermistor (NTC) temperature sensor, a vibration sensor and the ability to detect a stalled motor, disconnected motor-phase, or running over load. The single-wire FAULT bus is based on
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an open-drain architecture and enables the BridgeSwitch ICs to send status updates using an 8-bit word, with the 8th bit providing odd- parity to ensure signal integrity. It is also used by the MCU to send: ● Commands to the BridgeSwitch ICs; ● Queries to the BridgeSwitch ICs for status updates, and; ● Reset commands to ICs that are latched-off for an over-temperature fault. The ID pin is used at power up to set a unique IHB identification for each BridgeSwitch IC, enabling the MCU to identify which IC provided a given fault alert; IHB1 has the ID pin connected to BPL, the ID pin is floating for IHB2 and the ID pin is connected to SG for IHB3 (Figure 4). In addition, setting
MotorExpert accelerates time to market
MotorExpert software features speed and current control loop functions and includes an embedded C code application, library, and control GUI that supports single- phase designs using BridgeSwitch ICs.(3) It accelerates time to market by providing a graphical interface to all parameters and commands, as well as a terminal emulator for interacting with the motor controller in serial mode. The Motion Scope window displays real-time linear graphs of controller variables. New functions and use cases can be added and users can easily port the software to an MCU. The software needs only 14 kB of code memory and 5 kB of SRAM, making it suitable for running on MCUs with limited memory resources. Software developed using MotorExpert meets static (MISRA) and dynamic performance requirements for
latency, jitter and execution time. Conclusion
Designers can turn to BridgeSwitch ICs with built-in system fault diagnosis to reduce field returns and speed time to market. These self-powered, half-bridge motor driver ICs deliver the high efficiency, design flexibility, and enhanced inverter and system reliability demanded in modern consumer appliances. The extensive hardware-based protection functions save certification time and costs. These ICs are IEC 60335-1 & 60730-1 compliant as confirmed in UL Report 4788685352. The ID pin enables the MCU to pinpoint the location of faults. Finally, the use of MotorExpert design software further speeds time to market for single-phase applications of BridgeSwitch ICs.
www.power.com References
1 Understanding Compressor Electronics, Emerson
Climate; Chapter 2, Page 3 2
Electrical Appliances 3
UL Report 4788685352, UL Informative Report IEC 60335-1 Safety of Household and Similar
BridgeSwitch Motor-Expert Motor Control Configuration and Diagnostics Tool, Power Integrations
Components in Electronics December/January 2023 29
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