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Product(s)

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Product(s)

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APPLICATION NOTE

5/13

Rsense

Rp

1

2

Overvoltage

reference

(+/- 270 V)

Overvoltage

detector

Overcurrent

detector

OR

TIPL

TIPS

FS

SW3 SW1

Fuse

TIP

GND

-Vbat

External

voltage

reference

V

A2

LG

4

5

6

Fig. 6: Switching by current during speech mode.

In normal conditions, the working point of this circuit is located in region 4 of A2 curve : the CLP270M is idle.

for positive and negative surges.

short-circuited to GND.

The operating point moves to region 5 for positive surges or region 6 for negative surges.

(region 4).

In normal operating condition the current (typically below -100 mA) should not activate the protection

device CLP270M. Therefore the level of activation has to be chosen just above this limit (-200 mA). This

Example:

Ω ensures a negative triggering of -190 mA min and -320 mA max. In this case, the

positive triggering will be 150mA min and 280 mA max.

3

5

7

9

11

13

0.2

0.3

0.5

1

2

Rsense ( )

Ω

ISWON (T, Rsense) / ISWON (25°C, 4

)

Ω

@-20°C @25°C

@75°C

35

7

9

11

50

100

200

300

500

Rsense ( )

Ω

Iswon @ 25°C (mA)

Iswon min

negative

Iswon max

negative

Iswon min

positive

Iswon max

positive

4. Speech mode

In speech mode (Ring relay in position 1), the protection is provided by the combination of both CLP270M

and the external voltage reference device (see figure 6)