MCP2551 CAN Transceiver Features, Working Principle, MCP2551 vs TJA1050

Ⅰ. Overview of MCP2551 transceiver

Ⅱ. Manufacturer of MCP2551 transceiver

Ⅲ. Features of MCP2551 transceiver

Ⅳ. Working principle of MCP2551 transceiver

Ⅴ. Block diagram of MCP2551 transceiver

Ⅵ. What is the difference between MCP2551 and TJA1050?

Ⅶ. What are the applications of MCP2551 transceiver?

Ⅷ. How does MCP2551 transceiver implement CAN protocol control and physical bus interface?

MCP2551 is a fault-tolerant high-speed CAN device that can be used as a CAN protocol controller and physical bus interface. It has differential transceiver capabilities, fully complies with ISO-11898 standards, and meets 24V voltage requirements. On a CAN system, each node usually requires a device to convert the digital signals generated by the CAN controller into signals suitable for bus transmission. In addition, it adds a buffer between the CAN controller and high-voltage spikes that may be generated by external devices.

Replacements and equivalents:

• ATA6561

• ATA6562

• LTC2875

• PCA82C250

The MCP2551 is manufactured by Microchip Semiconductor. The company was founded in 1989 and is headquartered in Arizona. Microchip Semiconductor is a world-leading supplier of microcontrollers and analog semiconductors, providing low-risk product development for thousands of consumer products, helping customers reduce total system costs and accelerate product time to market. Nowadays, Microchip has launched a variety of microcontroller peripherals, RFID smart cards, KEELOQ security products and analog products, enabling it to design more comprehensive embedded control system solutions to meet the growing needs of users.

• Low current standby operation

• Automatically detects ground errors at TXD input

• Supports 1MB/S operating rate

• Can connect up to 112 nodes

• Meets the ISO-11898 standard physical layer requirements

• Externally controlled slope reduces RFI emissions

The working principle of MCP2551 mainly includes the physical layer and data link layer.

1. Working principle of physical layer 

MCP2551 uses differential transmission technology to transmit data through two signal lines, CAN_H and CAN_L. The voltage difference between CAN_H and CAN_L represents the logical state of the data. When the voltage of CAN_H is higher than CAN_L, it indicates logic 1; conversely, when the voltage of CAN_H is lower than CAN_L, it indicates logic 0. Through its built-in differential driver and differential receiver, MCP2551 can easily convert the digital signal of the microcontroller into a stable differential signal, ensuring the stability of the differential signal so that it can be accurately interpreted by the microcontroller. MCP2551 also has excellent anti-interference ability, which can maintain signal stability in noisy environments.

2. Working principle of data link layer

MCP2551 uses the CAN protocol, which defines the data transmission format and transmission rules. The main task of the data link layer is to divide data into frames and transmit them with the help of the CAN bus. MCP2551 integrates a CAN controller and can automatically send and receive data. When the microcontroller needs to send data, it transmits the data to the MCP2551 and sets the corresponding CAN identifier and data length. MCP2551 will encapsulate the data into CAN frames and send them out through the CAN bus. When other nodes receive this CAN frame, the MCP2551 will automatically decapsulate it and transmit the data to the microcontroller.

1. EMC performance

TJA1050 uses automatic slope control to ensure that the output level has extremely low electromagnetic radiation. The MCP2551 requires the user to adjust the slope through the baud rate, similar to the previous PCA82C251. Despite this, the TJA1050 is relatively convenient to use.

2. Output symmetry

Because TJA1050 has excellent output symmetry, its ability to resist common mode interference is very strong even without adding a common mode coil. According to the survey, the performance of TJA1050 in group pulse test is 5% higher than that of MCP2551.

3. Compatibility

TJA1050 is a new type of transceiver that is compatible with PCA82-250 transceiver. This means that in some systems we can use the TJA1050 as a replacement for the PCA82-250. However, it should be noted that the MCP2551 will not work properly in the PCA82C250 system.

4. Minimum baud rate

In order to prevent the ICU's TxD pin from being low for a long time and thus affecting the bus, the new CAN transceiver adopts a minimum baud rate limit. Under stable operation, TJA1050 usually supports a baud rate of more than 60,000 bits/second (minimum support of 20,000 bits/second), while MCP2551 supports a baud rate of more than 16,000 bits/second (minimum support of 19,200 bits/second). TJA1050 can cut off the error signal faster when there is a bus error to ensure normal communication. 

• Medical equipment: In some medical equipment, especially equipment that requires multiple modules to work together, the CAN bus and MCP2551 can be used to achieve efficient communication between these modules.

• High-speed communication: The MCP2551 supports CAN communication rates up to 1 Mbps, making it suitable for applications requiring fast data transmission, such as automotive control systems.

• Communication equipment: It is applicable in communication devices necessitating fast and dependable communication, particularly in settings demanding strong resistance to interference and enhanced reliability.

• Industrial automation: The MCP2551 finds application in industrial control systems, serving as a means to establish real-time communication between devices such as sensors, controllers, and actuators. Its usage is crucial in the development of distributed control systems.

• Automotive electronic systems: CAN bus is widely used in automotive electronic systems. It is used to connect various electronic control units (ECUs), such as engine control units (ECUs), air conditioning controls, and anti-lock braking systems (ABS). MCP2551 can be used to connect these modules to achieve high-speed and reliable communication between them.

First, the MCP2551 adds a buffer between the CAN controller and the high-voltage spikes on the CAN bus. These high-voltage spikes may be generated by external devices (such as EMI, ESD, electrical transients, etc.). Adding a buffer can effectively reduce the impact of these signals on the CAN controller and CAN bus, and improve the reliability and stability of the system.

Secondly, the MCP2551 offers a differential transceiver function for the CAN protocol controller. It adheres entirely to ISO-11898 standards, ensuring compliance with 24V voltage specifications. Consequently, the MCP2551 can effectively accommodate the needs of the CAN protocol controller, converting them into signals suitable for transmission over the CAN bus.

In addition, MCP2551 also uses a dual-row 8-pin package, suitable for 12V and 24V systems. This means it can adapt to different system voltage requirements and work with different CAN protocol controllers and physical bus interfaces.

Frequently Asked Questions

1. What is the use of MCP2551?

The MCP2551 provides differential transmit and receive capability for the CAN protocol controller and is fully compatible with the ISO-11898 standard, including 24V requirements. It will operate at speeds of up to 1 Mb/s.

2. What is MCP2551?

The MCP2551 is a high-speed CAN, fault-tolerant device that serves as the interface between a CAN protocol controller and the physical bus.

3. What is Transceiver IC?

RF Transceiver ICs are semiconductor devices that consist of a transmitter and a receiver in a single package. Transceivers are designed to function proficiently within an RF family or standard such as AISG, Bluetooth, ISM, VHF, Wi-Fi, cellular, RADAR, 802.15.

4. What is the pinout of MCP2551?

TXD is a TTL-compatible input pin. The data on this pin is driven out on the CANH and CANL differential output pins. It is usually connected to the transmitter data output of the CAN controller device. When TXD is Low, CANH and CANL are in the Dominant state.

5. How does MCP2551 work?

It acts as an interfacing device between CAN protocol and the physical bus. The device, MCP2551 provides differential transmit and receive capabilities and is compliant with the ISO-11898, including the 24V requirements. Data transfer rate of up to 1Mb/s is achievable with this module.