TISP3070H3SL THRU TISP3095H3SL, TISP3125H3SL THRU TISP3210H3SL
TISP3250H3SL THRU TISP3350H3SL
DUAL BIDIRECTIONAL THYRISTOR OVERVOLTAGE PROTECTORS
JANUARY 1999 - REVISED MAY 1999
APPLICATIONS INFORMATION
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.
PEAK VOLTAGE
STANDARD
SETTING
V
GR-1089-CORE
2500
1000
1500
FCC Part 68
(March 1998)
I3124
ITU-T K20/K21
800
1500
1000
1500
1500
4000
VOLTAGE
WAVE FORM
µs
2/10
10/1000
10/160
10/560
9/720 †
9/720 †
0.5/700
10/700
PEAK CURRENT
VALUE
A
500
100
200
100
37.5
25
37.5
37.5
100
CURRENT
WAVE FORM
µs
2/10
10/1000
10/160
10/560
5/320 †
5/320 †
0.2/310
5/310
TISP3xxxH3
25 °C RATING
A
500
100
250
160
200
200
200
200
SERIES
RESISTANCE
Ω
0
0
0
0
0
0
0
† FCC Part 68 terminology for the waveforms produced by the ITU-T recommendation K21 10/700 impulse generator
If the impulse generator current exceeds the protectors current rating then a series resistance can be used to
reduce the current to the protectors rated value and so 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 generators peak voltage by the protectors rated current. The
impulse generators fictive impedance (generators 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 10, the appropriate series resistor value can be calculated for ambient temperatures in the range
of -40 °C to 85 °C.
a.c. power testing
The protector can withstand the G return 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
ampere. 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).
capacitance
The protector characteristic off-state capacitance values are given for d.c. bias voltage, V
D
, values of 0, -1 V,
-2 V and -50 V. Where possible values are also given for -100 V. Values for other voltages may be calculated
by multiplying the V
D
= 0 capacitance value by the factor given in Figure 6. Up to 10 MHz the capacitance is
essentially independent of frequency. Above 10 MHz the effective capacitance is strongly dependent on
connection inductance. In many applications, the typical conductor bias voltages will be about -2 V and -50 V.
other at -50 V.
PRODUCT
INFORMATION
9
POINN [ POWER INNOVATIONS LTD ]
