AN2689 datasheet(30/42 Pages) STMICROELECTRONICS

Il numero della parte	AN2689

Spiegazioni elettronici	Protection of automotive electronics from electrical hazards

PDF	42 Pages

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Produttore elettronici	STMICROELECTRONICS [STMicroelectronics]

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30 / 42 page

Supply rail protection

AN2689

30/42

Doc ID 14310 Rev 3

Figure 40.

LD5505 output voltage in open circuit

Figure 41.

LD5505 output current in short circuit

Figure 41 shows the current waveform corresponding to the pulse 5a of the ISO 7637-2

standard delivered by the SCHAFFNER NSG5500 generator when terminations are short

circuited

The tp duration measured between Ip and Ip/2 is 28.5 ms. Then the time constant calculated

is 40.7 ms (generator outputs short circuited).

4.5.1

Determination of Rd

For tp > 1 ms, Rdtp is given by:

tp is in seconds in this case.

, and  define the transient thermal impedance (see Table 3: Transient thermal impedance

versus packages).

When the surge is applied to the RBO40-40 transient suppressor:

And the time constant is

= R

sC.

Test conditions

87 V, 100 ms

13.5 V battery voltage

Rs = 2

Ipp = 40 A

At I = 0.5 Ipp, tp = 0.7

= 40.7 ms

tp = 28.5 ms

nom

Vbr

TRth

⎟⎟⎠

⎞

⎜⎜⎝

⎛

() 2

RBO

AN2689 Scheda tecnica(PDF) 30 Page - STMicroelectronics