MC33661 Features and Application in Automotive Electronics
Update Time: 2020-04-01 10:26:31
With the rapid development of information technology, the proportion of automotive electronics products in automobiles is becoming larger and larger, and automotive electronics technology has gradually become one of the characteristics of automotive high-tech. LIN (Local Interconnect Network) is a low-cost serial communication network. It is now more widely used to implement distributed electronic system control in automobiles. The goal of LIN is to provide auxiliary functions for existing automotive networks such as the CAN bus. The LIN bus is based on the universal asynchronous serial port (UART) of a point-to-point computer. It is equipped with a bus driver suitable for multipoint communication, plus the LIN bus communication protocol to form an inexpensive serial bus control system. The LIN bus is High-end communication bus, such as CAN (Controller Area Network) bus, auxiliary bus. Where the bandwidth and functions of the CAN bus are not required, such as the control of doors, windows, rear-view mirrors, communication between smart sensors and braking devices, the use of the LIN bus can greatly save costs. LIN bus driver MC33661.
In the past, there were MC33399 and other LIN bus drivers. Over time, their deficiencies gradually emerged, such as the mode is too single, the flip frequency cannot be adjusted effectively, sometimes the device consumes large power, and sometimes it seems that the driving power is not enough, etc. The birth of MC33661 has greatly improved this situation.
The MC33661 chip is available in a common 8-pin plastic package.
MC33661 chip has the following features
First, flip frequency can be selected to optimize communication at 10kbps and 20kbps baud rates
Second, under special mode of test and programming operation, the communication baud rate can be higher than 100kbps
Third, with efficient waveform shaping circuit, providing excellent electromagnetic compatibility performance
Fourth, conventional DC power supply voltage 6-18V, can withstand 27V, can withstand the recharge voltage up to 40V when the power is suddenly unloaded
Fifth, lIN bus pins can withstand + 40V-18V DC voltage
Operation mode and application circuit
The MC33661's multiple operating modes greatly improve the performance of the LIN bus driver. MC33661 has a series of operation modes such as normal mode, low speed mode, high speed mode, and sleep mode. This greatly enriches the functions of the chip, and users can set the chip mode accordingly according to different needs, and improve the efficiency of the chip while reducing losses as much as possible. This makes it have a great advantage in the competition with the same type of chip, is a strong support for LIN bus applications.
When the MC33661 is selected as the normal mode, the LIN bus is in a normal working state, and the device's operating frequency and timing comply with the LIN bus protocol specification, and the communication rate is 20kbps.
When the LIN bus is tested in the ECU and the program is downloaded to the microcontroller, the MC33661 can select high-speed mode and the communication frequency can reach 100kbps.
The MC33661 can enter low-speed mode to further reduce the electromagnetic radiation level of the LIN bus, although the electromagnetic radiation level in the normal working mode is not high.
The MC33661 has a sleep mode. The power consumption in the sleep mode is extremely low. The information required for fast startup during sleep is retained, so fast startup can be achieved.
A typical circuit using the MC33661 as a master node. When used as a slave node driver, it is not necessary to connect the diode and pull-up resistor at the Mask node pull up terminal, and directly connect to the LIN bus driver LIN bus. On the one-chip computer side, the sending and receiving ends of the SCI port are directly used to control communication, and one I / O port of the one-chip computer is used as an output to control the working mode. The power terminal is directly connected to the 12V car battery. When the vehicle is powered off, the driver enters the sleep mode.Tag: MC33661