AN2689 datasheet(36/42 Pages) STMICROELECTRONICS

tên linh kiện	AN2689

Giải thích chi tiết về linh kiện	Protection of automotive electronics from electrical hazards

PDF	42 Pages

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nhà sản xuất	STMICROELECTRONICS [STMicroelectronics]

Trang chủ	http://www.st.com

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36 / 42 page

PCB layout recommendations

AN2689

36/42

Doc ID 14310 Rev 3

Then

Therefore, for L1, the over voltage is

and for L2 the over voltage is

That means the total over voltage seen by the module would be something close to Vcl +

100 V! This shows that whatever the protection device, if the routing is not optimized there

will be a big impact of the track inductance to the protection device on the remaining voltage

in case of fast transient discharge. Figure 53. illustrates the recommended Transil wiring to

prevent this phenomenon.

Figure 53.

Recommended Transil wiring

The equivalent schematic diagram for the recommended wiring layout is shown in Figure 54.

Figure 54.

Details of the remaining voltage at the module to protect

In this layout the remaining voltage at the module to protect is:,

So, in the worst case (when L3 = L4 = 0), V is equal to VCL.

⇒

≈

Module to protect

Vnom

Vmax

Transil in

SMA package

L1di/dt

+25kV ESD ISO10605

L2di/dt

Vcl

Module to protect

Vnom

Vmax

L3di’/dt

L4di’/dt

L1=L3 & L2=L4

I’

Vcl

AN2689 bảng dữ liệu(PDF) 36 Page - STMicroelectronics