TISP4xxxH3LM Overvoltage Protector Series

Deployment

NOVEMBER 1997 - REVISED JANUARY 2010

Specifications are subject to change without notice.

Customers should verify actual device performance in their specific applications.

APPLICATIONS INFORMATION

These devices are two terminal overvoltage protectors. They may be used either singly to limit the voltage between two conductors

(Figure 12) or in multiples to limit the voltage at several points in a circuit (Figure 13).

Figure 12. Two Point Protection

Figure 13. Multi-point Protection

Th1

Th3

Th2

Th1

protect circuits without a ground reference, such as modems. In Figure 13, protectors Th2 and Th3 limit the maximum voltage between each

protector Th1 is not required.

Impulse Testing

To verify the withstand capability and safety of the equipment, standards require that the equipment is tested with various impulse wave

forms. The table below shows some common values

.

If the impulse generator current exceeds the protector’s current rating, then a series resistance can be used to reduce the current to the

protector’s rated value to prevent possible failure. The required value of series resistance for a given waveform is given by the following

calculations. First, the minimum total circuit impedance is found by dividing the impulse generator’s peak voltage by the protector’s rated

current. The impulse generator’s fictive impedance (generator’s peak voltage divided by peak short circuit current) is then subtracted from the

minimum total circuit impedance to give the required value of series resistance. In some cases, the equipment will require verification over a

temperature range. By using the rated waveform values from Figure 11, the appropriate series resistor value can be calculated for ambient

temperatures in the range of -40 °C to 85 °C.

Standard

Peak Voltage

Setting

V

Voltage

Waveform

µs

Peak Current

Value

A

Current

Waveform

µs

TISP4xxxH3

25 °C Rating

A

Series

Resistance

Ω

GR-1089-CORE

2500

2/10

500

2/10

500

0

1000

10/1000

100

10/1000

100

FCC Part 68

(March 1998)

1500

10/160

200

10/160

250

0

800

10/560

100

10/560

160

0

1500

9/720 †

37.5

5/320 †

200

0

1000

9/720 †

25

5/320 †

200

0

I3124

1500

0.5/700

37.5

0.2/310

200

0

ITU-T K.20/K 21

1500

4000

10/700

37.5

100

5/310

200

0

† FCC Part 68 terminology for the waveforms produced by the ITU-T recommendation K.21 10/700 impulse generator

AC Power Testing

The protector can withstand currents applied for times not exceeding those shown in Figure 8. Currents that exceed these times must be

terminated or reduced to avoid protector failure. Fuses, PTC (Positive Temperature Coefficient) resistors and fusible resistors are overcurrent

protection devices which can be used to reduce the current flow. Protective fuses may range from a few hundred milliamperes to one am-

pere. In some cases, it may be necessary to add some extra series resistance to prevent the fuse opening during impulse testing. The current

versus time characteristic of the overcurrent protector must be below the line shown in Figure 8. In some cases, there may be a further time

limit imposed by the test standard (e.g. UL 1459 wiring simulator failure).

OBSOLET

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