RSM485M

RSM485M is an ultra-compact, high-speed isolated RS-485 transceiver module that provides electrical isolation between microcontrollers such as MCU, ARM, or DSP and the RS-485 bus. It eliminates loop currents caused by ground potential differences between communication nodes, reduces noise interference, improves communication quality, and enhances data transmission stability. The RSM485M features automatic transceiver direction control, eliminating the need for the controller to provide RS-485 transmit/receive switching control signals. The module automatically switches between transmit and receive states based on the serial transmit signal level. The maximum data transfer rate reaches 500kbps. The module integrates an isolated DC/DC converter internally, requiring only a DC power supply from the controller side — no isolated power supply or additional peripheral components are needed for the RS-485 transceiver. Up to 64 nodes can be connected to the same bus network. RSM485M is an ultra-compact, high-speed auto-switching isolated RS-485 transceiver module with an integrated high-speed digital isolator and isolated DC/DC converter. It achieves full electrical isolation between the controller's UART interface and the RS-485 bus, enhances common-mode voltage tolerance across the isolation barrier in the data link, eliminates loop currents caused by ground potential differences between nodes, reduces noise interference, improves communication quality, and increases bus stability. The digital isolator enables data transfer rates of up to 500kbps. The integrated DC/DC isolated converter requires only a 3.3V or 5V input from the controller side — no isolated power supply design is needed for the RS-485 interface circuit. This product features automatic RS-485 transceiver direction control, eliminating the need for the controller to provide transmit/receive switching control signals to the RS-485 transceiver. The module automatically determines the transceiver state from the transmit signal and switches between transmit and receive functions automatically. When the receiver input voltage (VA - VB) ≥ -10mV, ROUT outputs a high level. When (VA - VB) ≤ -200mV, ROUT outputs a low level. When TXD input is high, the transmitter output state is determined by the bus differential voltage. To ensure normal bus communication, the module integrates internal pull-up and pull-down resistors, which typically ensure a bus differential voltage (vA - vB) ≥ -10mV without requiring external pull-up or pull-down resistors.

Applications

• Industrial Automation
• Battery Management Systems
• New Energy
• Building Automation
• Power Monitoring
• Coal Mining & Oilfield

Key features

• Single supply input (3.3V or 5.0V)
• Integrated DC/DC isolated power supply
• Isolated output power pins
• 2500VDC isolation voltage
• 500kbps data rate
• Auto-direction control for data transceiving
• Ultra-compact DIP8 package
• Excellent EMC performance
• Up to 64 nodes on a single bus
• Operating temperature range: -40°C~+105°C