AN2689 datasheet(9/42 Pages) STMICROELECTRONICS

Nome de Peças	AN2689

Descrição Electrónicos	Protection of automotive electronics from electrical hazards

PDF	42 Pages

Scroll/Zoom	100%

Fabricante Electrônico	STMICROELECTRONICS [STMicroelectronics]

Página de início	http://www.st.com

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9 / 42 page

AN2689

Data line protection

Doc ID 14310 Rev 3

9/42

Data line protection

3.1

Protection topologies

3.1.1

Clamping topology

Various protection topologies can be chosen for data line protection. There is the usual

topology that consists of using a clamping device as shown in Figure 6. The action of the

suppressor upon positive and negative surge occurrence is shown respectively in Figure 7

and Figure 8.

Figure 6.

Data line protection using a Transil™

When a positive surge occurs, the over voltage is suppressed by the Transil as the voltage

passes the breakdown voltage (VBR). Thus the current is diverted to ground. The remaining

voltage on the data line is limited to the clamping voltage (Vcl).

Figure 7.

Positive surge suppression

For the negative surge, the Transil is now in forward mode and the over voltage is eliminated

as the surge voltage passes the forward voltage drop of the protection device (Vf). The

remaining voltage is limited to the peak forward voltage of the Transil (Vfp).

Figure 8.

Negative surge suppression

Module to protect

Vnom

Vmax

Transil

Module to protect

Vnom

Vmax

Vcl

Vcc

Module to protect

Vnom

Vmax

Vfp

Vcc

AN2689 Folha de dados(PDF) 9 Page - STMicroelectronics