Seektronics

Polarity components require special attention throughout the PCBA process, as errors in directional components can lead to batch accidents and failure of the entire PCBA board, so it is extremely important that engineering and production staff understand SMT polarity components.   l  Polarity definition   Polarity means that the positive and negative poles or the first pin of the component are in the same direction with the positive and negative poles or the first pin on the PCB(printed circuit board). If the direction of the component does not match with that on the PCB, it is called reverse defect.   l  polarity identification method   1.  Resistor  without polarity 2.  Capacitor 2.1 Ceramic capacitors  without polarity 2.2 Tantalum capacitors  have polarity PCB board and components positive marking: 1) colour band marking; 2) "+" sign marking; 3) angled marking. 2.3 Aluminium electrolytic capacitors  have polarity Part marking: colour band for negative; PCB board marking:

  Out of stock, price rise, the global lack of chips increasingly intense.   Recently, the global power semiconductor leading Infineon is brewing a new round of product prices, prices or up to 12%! Similarly, the world's largest foundry TSMC also rumored in July will be adjusted upward, the rate of 15 ~ 30%.   And accompany of out of stock rise in price, is the chaos .   Chaos 1: Fakes proliferate   From masks to vaccine passports to chips: almost all products that have been in high demand over the past year or so have inevitably provided opportunities for fraudsters hoping to make easy money by faking them.   The shortage of chips has increased prices, leading companies to place orders with suppliers who do not pass quality checks, thus flooding them with counterfeit goods. Studies have shown that as lead times increase, manufacturers are under pressure to source parts quickly and start sourcing from third-party distributors. Soon, counterfeit products entered the supply chain.  

PCB Cloning is known as PCB Copy or PCB duplication. It is a reversely researching technology based on existing physical PCB boards, to obtain a good electronic product PCB design circuit, as well as the circuit schematic diagram and BOM table. It is the integrated tasks of PCB reverse engineering, IC unlock (also referred das IC crack), PCB prototype and debug, then re-production.   PCB cloning basic steps   1. When you get a PCB, first record on paper the type, parameters and position of all the components, especially the diodes, the direction of the triplet and the direction of the IC gap. It is best to use a digital camera to take two photos of the location of the components. Nowadays, the PCB circuit board more and more advanced above the diode triode some do not pay attention to do not see.   2. Remove all components and remove the tin from the PAD hole. Clean the empty PCB board with ultrasonic wave, and then put it into the scanner. Note that the PCB must be placed horizontally

In the peripheral circuit design of DC-DC BUCK chips, we usually add capacitors or a combination of capacitors + resistors between the BOOT and SW pins, this piece of circuit is called bootstrap circuit, the capacitors and resistors in the bootstrap circuit are called bootstrap capacitors and bootstrap resistors.   What is a bootstrap capacitor?   DCDC Buck chip has a pin called BOOT, and some are called BST. The following is an explanation of the BOOT pin of a DCDC chip. In the external circuit design, a capacitor, generally 0.1uF, is needed between the BOOT and SW pin, and is connected to the driver end of the high-end MOS tube of DCDC.     How does a bootstrap capacitor work?   The following is a block diagram of a DCDC BUCK chip, the top NMOS is called the high-side MOSFET and the bottom NMOS is called the low-side MOSFET.     When the high side MOS tube is turned on, SW is VIN, SW charges and stores energy in the inductor, and the inductor current is rising; when the low side MOS