Cosine nanoelectronics launched the RS485 chip COS13487EESA with automatic transceiver control function
Cosine nanoelectronics launched the RS485 chip COS13487EESA with automatic transceiver control function
Blog Article
RS-485 is a half-duplex communication interface that uses differential signals for transmission, also known as TIA-485-A, ANSI/TIA/EIA-485 or TIA/EIA-485. Because it is half-duplex, in the usual use of 485 communication, it is necessary to switch the sending or receiving function. The conventional method is to use the RE pin and DE pin (see Figure 1) to switch the receiving data and sending data through the program, but it is more troublesome to write the program and it is more difficult to debug. In order to facilitate the debugging of the code, many engineers build additional circuits on the periphery of the chip to realize the automatic switching of the receiving and sending data functions, but this increases the circuit board area and workload.
COS13487EESA of Cosine nanoelectronics is an RS-485 transceiver with integrated automatic direction selection control function (see Figure 2). In addition, it has hot-swap function, which can eliminate fault transient signals on the bus during power-on or hot insertion. It can be seen that the pins of COS13487 and COS485 are different only in pin 3, and the other pins are the same. From the pin function, it can be seen that pin 3 is the shutdown pin. When pin 3 is high, the chip is in normal mode. When pin 3 is low, the chip will enter shutdown mode. The function of pin 2 is one more function than that of pin 2 of the conventional COS485 chip. When pin 2 is low, the chip is in receiving mode. When pin 2 is high, the chip will enter automatic direction control mode. At this time, both receiving data and sending data are automatically switched inside the chip, without the participation of programs and external circuits.
Product Features
• Automatic direction control function automatically enables the driver during transmission
• Hot-swap for telecommunications equipment
• Enhanced slew rate limiting function helps achieve error-free data transmission (COS13487E)
• High-speed device (COS13488E) allows up to 16Mbps transmission rate
• Enhanced ESD protection of ±15kV human body model for RS-485 I/O pins
• With 1/4 unit load, up to 128 transceivers can be connected to one bus
• Operating temperature range: -40°C to 125°C
• 8-pin SOP package
Typical Application
The typical application circuit below is an isolated RS-485 interface implemented using COS13487EESA. The transceiver and control circuit use different power supplies. Connect pins 2 and 3 to high level, and the chip will be in automatic direction control mode. The application of other pins is the same as that of COS485 chip and no modification is required.
COS13487 of Cosine nanoelectronics has automatic transceiver control function, which can save external isolators and only requires two optocouplers to achieve electrical isolation of the transceiver. By comparison, it can be seen that it is more convenient and efficient to use COS13487 chip for 485 communication processing.
Basic introduction of the brand
Cosine nanoelectronics is a Sino-foreign joint venture focusing on the research and development and sales of high-performance, high-quality analog and RF integrated circuit chips. The company focuses on the field of high-end domestically produced independent controllable analog chips. After more than 6 years of engagement in this sub-industry, it has successively launched: signal conditioning chips, high-voltage driver chips, RF transceiver chips, interface and isolation chips, and power management chips. There are about 200 chips in 4 series. The chip performance is benchmarked against international first-class manufacturers.
MAX13487EESA+T is a half-duplex RS-485/RS-422 compatible transceiver produced by Maxim with automatic direction control function. It is widely used in automatic HVAC systems, industrial control, industrial motor drive, isolated RS-485 interface and electric meter.
Generally speaking, the main functions of MAX13487EESA+T are as follows:
1. Data transmission: As an interface chip for RS-485/RS-422 communication protocol, MAX13487EESA+T can send and receive data to achieve communication between devices.
2. Automatic direction control: With automatic direction selection control function, the driver can be automatically enabled during transmission, thereby simplifying the control of communication direction.
3. Hot-swap protection: With hot-swap function, it can eliminate fault transient signals on the bus during power-on or hot insertion to protect communication equipment.
4. ESD protection: Provides ±15kV enhanced ESD protection, which enhances the protection against electrostatic discharge.
5. High-speed data transmission: The driver of the MAX13487E series has a low slew rate and can achieve error-free data transmission up to 500kbps
6. Multi-device connection: With a 1/4 unit load receiver input impedance, up to 128 transceivers can be connected to a bus, which is suitable for building large-scale communication networks.
The price of MAX13487EESA+T suddenly rose sharply, and it once became a "magic material" on the market. It is understood that since July 2023, the price of MAX13487EESA+T has slowly increased, and suddenly the popularity soared at the beginning of this year. The price of this material was still 7 yuan in December last year, and it rose to 18 yuan in January this year. After that, it continued to rise straight. The market quotation in March has reached 30 yuan, which makes people call it crazy.
Finally, I would like to recommend that the domestic alternative to MAX13487EESA+T can be COS13487EESA. COS13487EESA is an RS-485/RS-422 interface chip produced by Keshan Chuangxin. Compared with MAX13487EESA, its performance parameters meet various application requirements, and it is cost-effective and an excellent choice for domestic cost reduction.