AN320 datasheet(10/13 Pages) STMICROELECTRONICS

Part #	AN320

Description	In the field of parallel protection, the devices used have two main functions in transient operation

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Manufacturer	STMICROELECTRONICS [STMicroelectronics]

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Physical operation

AN320

10/13

Doc ID 5649 Rev 3

Figure 13.

Operation in the avalanche mode

Application of a negative voltage on cathode N++ results in forward biasing of junctions J1

and J3 and reverse biasing of J2. The current observed is thus the leakage current of

junction J2. When the voltage exceeds a certain value, junction J2, which is reverse biased,

begins to operate in the avalanche mode. The structure up to this current level operates like

a diode (junction J2). The side current biases the P1 layer next to the N1 part of the emitter.

The highly doped N1 layer has the same potential. The P1 area at the surface is forced to the

same potential as the N1 region by metallization.

N+ +

P1 +

P2 +

J 2

J 1

J 3

Avalanche current

()

AN320 Datasheet(PDF) 10 Page - STMicroelectronics