Precision PCB Fabrication, High-Frequency PCB, High-Speed PCB, Standard PCB, Multilayer PCB and PCB Assembly.
High frequency board refers to the high frequency circuit board which carry high frequency signal. High frequency signal can be defined as the frequency above 1GHz.It's more expensive than nomarl PCB. High frequency board are made of low dielectric constant, low high-frequency loss material. Currently most high-frequency board substrate is fluorine resin, such as polytetrafluoroethylene (PTFE), usually called Teflon, usually used in more than 5GHz situation.
For special circuit boards with higher electromagnetic frequencies, generally speaking, high frequency can be defined as a frequency above 1GHz. Its various physical properties, accuracy, and technical parameters require very high requirements, and are often used in automotive anti-collision systems, satellite systems, radio systems and other fields. The price is high, usually around 1.8 per square centimeter, which is about 18,000 yuan per square meter.
Whether the short-circuit protection function of the drive is designed well or not is very important to the safe operation of the power supply. It is necessary to get a drive circuit and test whether its short-circuit protection function is perfect before using it.
The high frequency of electronic equipment is the development trend, especially with the increasing development of wireless networks and satellite communications, information products are moving towards high speed and high frequency, and communication products are moving towards the standardization of voice, video and data for wireless transmission with large capacity and speed. The development of a new generation of products requires high-frequency substrates.
For the high-frequency driver and driver board with protection function, if the user wants to test the normal static output waveform (without the main power supply), the following points should be paid attention to:
1. If the power tube IGBT or MOSFET has been connected in the circuit, add the drive power supply and PWM input signal, you can see the corresponding output signal with an oscilloscope at the output end.
2. If the power tube is not connected, but an output test is being performed, then the two points that should be connected to the collector and emitter (or drain and source) of the power tube must be short-circuited. Because if the collector or drain is left floating, the driver or driver board will think that the power tube is in a short-circuit state and activate the internal protection mechanism. What you see at this time will be the protection signal waveform output by the driver, regardless of the waveform shape or cycle. The input PWM signal is completely different. The main problem to be solved in the application of IGBT is how to implement relatively perfect protection for IGBT in the case of over-current, short-circuit and over-voltage. Over-current faults generally take a longer time to overheat the power supply, so its protection is solved by the main control board. Overvoltage generally occurs when the IGBT is turned off, and the larger di/dt generates a higher voltage on the parasitic inductance, which requires a snubber circuit to clamp or appropriately reduce the turn-off rate. After a short-circuit fault occurs, an extremely large current will be generated instantaneously, which will quickly damage the IGBT. The overcurrent protection of the main control board is too late and must be protected by the drive circuit or driver immediately.
