电源模块在RS232/RS485接口电路中的应用-海南世电科技

summarize

The development of the world's science and technology is changing rapidly, supercomputers, cloud computing, big data analysis, artificial intelligence, Internet of Things, new energy and other new technologies are developing rapidly, in addition to the pure software industry in the basic terminal hardware is not in great demand, the Internet of Things industry can not be separated from a large number of basic terminal products to support the construction of the Internet of Things grass-roots units. Each Internet of Things basic terminal products in accordance with its functional requirements, the need to collect, control multi-channel information (sensor information, single functional component control information) and so on, and the collection of this information, control and wired transmission are inseparable from the traditionalRS232/RS485isometricserial interfaceand signaling.

Due to the complexity of industrial IoT scenarios, the application of isolated power modules in the interface of IoT-based end products has become an indispensable component, and World Power has successfully launched 1W related isolated power modules.

The Role of Isolated Power Supplies

signal interference

RS232 output signal level (no-load maximum) ± 3 ~ 25V, RS485 output signal level (no-load maximum) for + / - 6V, level signal for the rectangular signal wave, its harmonics are very rich and complex, if directly accessed to the main circuit, these wave interference will be a great interference and damage to the main circuit

Suppression of electromagnetic interference and elimination of ground loops

Since the RS232/485 interface is an exposed interface, external static electricity and crosstalk pulses can cause breakdown damage to the main internal circuitry.

Isolated Power Supply Usage

Need to design an isolation circuit to isolate and convert external input signals, specifically need to isolate 2 places

The power supply needs to be physically isolated, the isolation voltage needs to reach 1500VDC DC voltage, generally use 5V-5V or 3V-5V power supply module to the level conversion circuit power supply, the power is generally in the 1W or so basically enough (U11 in the example figure:).ADUM1201), the name of the Seiden product is:MD500-050S0200The
After the signal level conversion also need to be isolated, need to use the isolation chip for isolation, isolation circuit as shown in the following example (isolation chip for the example of the U10).