Super Series for Automoive (SHA)/ Chip Surge Protection Device (CSPD)

　　Why automotive electronic control units (ECUs) need overvoltage protection: "Surge" refers to a sudden abnormal rise or fall in voltage in a short period of time, which often occurs in complex vehicle environments.

　　When electrical appliances that consume a large amount of power, such as electric windows and starter motors, are turned on or off, or when switches in the car are switched or circuit faults occur, surges will occur. Automotive electronic products are very afraid of surges, such as audio, driving computers and other precision electronic products. These products use a large number of microelectronic components inside, and microelectronic components are easily damaged by surges. Therefore, how to protect these precision electronic products from surges? Destruction has become a very important issue.

　　What is CSPD?

　　CSPD (Chip Surge Protection Device) is a patch-packaged surge voltage protection device. Nanjing Huaju Electronics Co., Ltd. has developed an ultra-high-performance overvoltage suppression device using professional powdering and production technology (with various multinational inventions) To protect electrical equipment, the SHA series of multi-functional overvoltage protectors are specially developed for use in automotive ECU power ports. SHA itself has a large capacitance that can provide better filtering effect on EMI noise. At the same time, SHA provides "ultra-small size SMD patch" packaging, and has "excellent high temperature characteristics" and "resistant to the highest 5a test standard". Compared with the current TVS on the market has always had the disadvantages of "high temperature characteristic attenuation" and "inability to withstand multiple surge impacts". SHA is the best choice for over-voltage components in the automotive industry.

　　Advantages of CSPD(SHN):

　　1. SMD type package (1206 ~ 2220)

　　2. Specifically designed for automotive-related electronic controllers (ECUs)

　　3. Inhibit voltage lower than (40V)

　　4. Extremely low leakage current (<10 μA)

　　5. The response speed is faster than plug-in MOV (< 1 ns)

　　6. High nonlinearity index α reaches (25 or more)

　　7. Passed ISO7637-2 Pulse 5a /5b test

　　8. Good impact ability more than 10 times 9. Comply with RoHS requirements and lead-free tin furnace

　　10. Non-polar two-way action

　　11.Extremely wide operating temperature - 55°C ~ +125°C

　　12. Avoid TVS high temperature performance degradation problem

　　13. Space saving and competitive price

　　3. Model name, appearance structure and dimensions:

Recommended part numbers for 12 V automotive systems:

Comparison between SCSMD patch pressure sensitivity and MOV and TVS

Main manufacturer specifications:

Why does a car need a load dump protection design? The full name of ECU is "Electronic Control Unit", which is called "electronic control unit" in Chinese. There are many ECUs in better cars now, which control various parts of the car, such as the electric motor. Injection engine, ABS, doors, windows, body, seats, etc., ECU is just a general term, and whatever it controls is called ECU. Load Dump─refers to the disconnection of the battery during the charging process of the alternator; in addition, the load dump phenomenon will also occur at the moment the car engine is started, which is the most energetic conduction interference pulse in the entire vehicle. . The reason for this is that when the generator is working, the heavy load is suddenly thrown away (such as the charging battery). This is because the energy on the generator inductance has nowhere to be released instantly, which will produce a few in the power supply circuit. Hundred volts, the rising edge is generally (5-10ms), and the half-peak width is approximately (100, 200, 300, 400, etc., depending on the power of the generator). Generally, in order to suppress the load-off voltage of the generator, it is usually set in the ECU The output will be connected in parallel with an overvoltage protector. The commonly used standard for surge tolerance testing of automotive electrical products is ISO7637. This standard simulates eight traditional surge waveforms in five categories that occur in automotive power supplies, including sudden interruption of power supply current, ignition switch switching, and windshield wiper motor operation. The power supply drops, etc., taking ISO7637 test pulse 5 as an example. This pulse wave describes the surge phenomenon caused by the power cut off of the wiper motor. Initially, the voltage VA is the power supply supplied to the car. Since the wiper motor switch is disconnected, When the power supply voltage drops to zero, the surge effect generated by the coil enters the vehicle electrical products and causes interference. The power supply is affected by the surge and no longer remains fixed. If the surge tolerance is insufficient, the vehicle electrical products will be affected or cause interference. destroy.

Application circuit description
(1)-C1 & C2 These two capacitors are mainly electrostatic capacitors. Considering that capacitor breakdown may cause a short circuit, the selected value is 1~47nF, and the rated voltage is above 100V.
(2)-R is a resistor with a general range of 0~22 ohm. Its main function is to share the load of Load Dump. But it cannot be too large and should be designed according to the actual current, because it will cause a voltage drop I×R. Pulse 5 in ISO7637 is Load Dump. The energy of the load is mainly absorbed through R and SHA. We also need to detect the voltage when the voltage is very low. Therefore, if R is too large, the system cannot be guaranteed to work at low voltage. If Rs is too small, the SHA load cannot be shared.
(3)-SHA is the main device for suppressing load dump.
(4)-Diode is an anti-reverse diode.
(5)-L4 and C3 are mainly used for EMC to prevent the current from changing too much.
(6)-C4 functions a bit like a small battery. The general value is between 100uF and 330uF. Several can be connected in parallel. Or add some high-frequency filter capacitors afterwards to mainly filter out high-frequency signals, such as pulses such as Pulse3a and 3b. Generally the value is between 1~47nf