Protection scheme for design of 24V system throwing load
In 2016, the total volume of mainland passenger car sales was about 300 thousand. When more trucks and buses were running on the road, another power supply system of our automotive system was also working, which is the power supply system of the 24V system.
The 12V system of power supply ports have been added to protect the sharpened throw load, so the load dump test are only 5B waveform test instead of 5A waveform.
In the new car ISO standard, the load test has replaced ISO-16750-2 (2010) as the old standard ISO-7637-2 (2004). The biggest difference between the 2 standards is that the new standard requires 10 minutes and 10 waveforms, while the old 7637-2 only requires testing 1 times the load waveform. The test Us voltage requirements are more stringent, from the original 174V limit increased to 202V, please refer to specific standards in the form:

For more stringent requirements, mainly to investigate the high reliability of power supply protection, it concerns a very important parameter, that is, product heat dissipation and electrical performance at high temperature.
So according to the new standard, put forward higher requirements for the protection of the TVS device, we strongly recommend using DO-218AB package with high power TVS device cooling plate, can guarantee high reliability when testing times.
From the specification point of view, the power of the SM8S series products are 6600W, the peak current varies due to the voltage, and the greater the voltage, the smaller the current. List the specifications first:


The working principle of TVS devices is to achieve the voltage Vc clamping voltage is smaller than the back value of DC-DC, the general product pressure under 60V, so 30V, 33V, 36V products are devices and general good, after all, many customers also need to do 36V pressure experiment for 1 minutes, so TVS device operating voltage should be chosen higher than 36V.
In the experiment, we have carried on the sample test to the device, the curve looks like:

This test is a rigorous test index in general project, but there will be encountered, such as excavators, cranes, more stringent requirements for internal resistance testing, as far as possible to reduce, even 1 ohm low resistance, as can be imagined, energy is rising exponentially.
In this case, the scheme recommended by tage series, this is a test of product consistency. Similar programs are available
SM8S18A *2, from the theoretical and testing results, can achieve 2 times the effect of energy, high demand has been adopted by customers.
SM8S12A *3 from the theoretical and testing results can achieve 3 times the effect of energy,
From the accumulation of a lot of on load dump and electrostatic protection and case selection, welcome to the needs of engineers to consult the official website of the customer service manager or electronic dance!