The MCP2551‑I/SN from Microchip Technology is a high‑speed CAN (Controller Area Network) transceiver that serves as the interface between a CAN protocol controller and the physical CAN bus . It provides differential transmit and receive capability for the CAN protocol controller and is fully compatible with the ISO‑11898 standard, including 24V system requirements .
The device converts the single‑ended TXD signal from the CAN controller into a differential signal on the CANH/CANL bus lines, and conversely converts differential bus signals into a single‑ended RXD signal for the controller. It also provides a buffer between the CAN controller and high‑voltage spikes that can be generated on the CAN bus by external sources such as EMI, ESD, and electrical transients .
The MCP2551‑I/SN features three operating modes controlled by the RS pin (pin 8) :
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High‑Speed Mode (RS = VSS): Fast output rise/fall times for high‑speed CAN bus rates.
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Slope‑Control Mode (RS connected to ground via resistor): Reduces EMI by limiting the rise and fall times of CANH and CANL. The slew rate is proportional to the external resistor value.
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Standby Mode (RS = VDD): Transmitter is switched off; receiver operates at lower current. The microcontroller can monitor RXD for bus activity.
Built‑in protection features include TXD permanent dominant detection, which disables the CANH/CANL drivers if TXD is held Low for more than 1.25 ms (minimum), preventing the bus from being permanently driven into the dominant state . The device also includes thermal shutdown(~165°C junction temperature) and short‑circuit protection .
The “I” in the part number indicates industrial temperature grade (−40°C to +85°C), while “SN” denotes the SOIC‑8 package .
