SM8T series of AUTO-GRADE TVS Diode, used for load dump protection of millimeter wave radar in Auto Industry

Radar systems are usually associated with military projects such as airplanes, recently they have quickly entered the civilian field, including commercial vehicles. As part of the advanced driver assistance system (ADAS) , millimeter wave radar systems are being integrated into new vehicles to provide a safer driving experience.

The power supply of mm WAVE RADAR is provided by the vehicle's 12V or 24V power supply. Various pulses may appear on the power supply due to different reasons, among which load dump is a common and more harmful one. The so-called load dump is when the car engine is running and the generator is delivering current to the car's power line. If the battery is suddenly disconnected, a higher surge voltage will be generated. It is characterized by high surge voltage, wide pulse width, and long duration. If it is not effectively protected, it will cause fatal damage to the rear pole circuit.

"As shown in Figure 1, it is an intuitive simulation of the principle of load dump protection, which is realized by installing a dedicated load dump protection TVS on the power supply. If the circuit is not adjusted to prevent surges, it is easy to cause the circuit loop Electronic devices are damaged due to overvoltage. Because the maximum pulse width of the load dump surge is generally about 350-400ms, and the corresponding pulse peak voltage is also relatively high, the maximum value of the 12V system is about 87V, and the maximum of the 24V system is about 174V, so the common TVS (only 10/1000us instantaneous pulse) cannot meet its protection requirements. A dedicated TVS for load dump protection needs to be connected in parallel to the power port, which can withstand wide pulse surges (350 millisecond pulse width). The power is also relatively large and meets the requirements of vehicle regulations.

figure 1:

DA Technology SM8T36C is connected in parallel to the 24V power supply terminal of a customer's millimeter-wave radar board,which can help the customer's board can pass the ISO7637 5A 174V 3 ohm wave impact smoothly .

In response to the above load dump protection requirements, DA Technology has launched a Uni&Bidirectional device, wide-pulse power, automotive-grade TVS SM8T series.

FEATURES as follows:

1. Designed specifically for load dump protection, can resist about 350ms pulse power, SMD DO-218AB package;

2. Both Uni/bidirectional products are available for prototype.

3. High peak current and stronger impact resistance;

4. It has the advantages of low leakage current and fast response time, while meeting the AEC-Q101 certification requirements;

5. Domestic devices, competitive on price &lead time.