AN821 APPLICATION NOTE

2/4

OUR PROPOSAL

To withstand these new requirements STMicroelectronics proposes an adapted input/output arrangement

for the THBT series.

Figure 2. STMicroelectronics proposal

Figure 2 shows our proposal that consists of following points:

– Insulation between inputs and outputs. For example TIP coming from the telecommunication network

is isolated from the TIP connected to the sensitive part of the circuit. That means, when the surge

suppressor is removed, no current can flow through the telecommunication equipment.

– For the component which has got four ground pins (like the THBT200xx), only two pins are enough to

withstand the maximum surge current capability of the component. That means only the two ground

pins located on the telecommunication equipment side are connected.

SUMMARY

New standards concerning the protection of the telecommunication network service personnel, and other

users of this network, from hazards in the equipment seems to be generalized. STMicroelectronics has

taken into account this fact and proposes to meet these requirements by layout like shown in Figure 2.

WITH COMPONENT ON BOARD

LAYOUT WITHOUT COMPONENT ON BOARD

TIP

TIP

TO THE

TELECOM.

NETWORK

TO THE

TELECOM.

EQUIPMENT

RING

RING

TIP

TIP

TO THE

TELECOM.

NETWORK

TO THE

TELECOM.

EQUIPMENT

RING

RING