AN2689 datasheet(23/42 Pages) STMICROELECTRONICS

23 / 42 page

AN2689

Supply rail protection

Doc ID 14310 Rev 3

23/42

4.3

Calculations for example 1

4.3.1

Determination of Rd

The voltage and current across the Transil are:

Because Rd is dependent on the surge current duration and because its value for

ISO 7637-2 pulse 2 is not given in the datasheet, it is necessary to determine it to solve the

equations. But this time the generator internal schematic is not provided and none of the

internal elements are known. So the easiest way to determine the current duration is to refer

to the generator characteristics that are given in Figure 29 and Figure 30. These curves

were produced from a SCHAFFNER NSG5500, MT5510 module. The voltage curve is for

open circuit and the current curve produced when terminations were short circuited.

Figure 29.

MT5510 output voltage in open circuit

Table 5.

SM15T33AY electrical characteristics (extract from datasheet)

Order code

IRM @ VRM

max

VBR @ IR

(1)

Pulse test: tp < 50 ms.

VCL @ IPP

10/1000 µs

VCL @ IPP

8/20 µs

T

max(2)

V

BR = T * (Tamb - 25) * VBR (25°C)

typ(3)

VR = 0 V, F = 1 MHz.

min. typ. max

max

µA

10-4/°C

SM15T33AY

28.2

31.4

34.7

45.7

59.0

169

9.8

2700

Table 6.

SM15T33AY thermal parameter (extract from datasheet)

Symbol

Parameter

Value

Unit

Rth(j-a)

Junction to ambient on printed circuit on recommended pad layout

°C/W

Ipp

Vbr

Vcl

max

Vbr

Ipp

max

Test conditions

50 V, 50 µs

Rs = 2

0.2 s period

AN2689 bảng dữ liệu(PDF) 23 Page - STMicroelectronics

AN2689 bảng dữ liệu(HTML) 23 Page - STMicroelectronics

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42

bảng dữ liệu tải về

Link URL