TISPPBL2SD
PROGRAMMABLE OVERVOLTAGE PROTECTORS
FOR ERICSSON COMPONENTS PBL 3xxx SLICS
AUGUST 1999
limiting voltage is shown in terms of the overshoot beyond the gate reference supply (V
GG
- V
(BO)
). Removing
the gate reference voltage level magnifies the thyristor limiting voltage variation and shows the data
stratification caused by the oscilloscope digitisation. Extrapolating the data trend indicates that the overshoot
is less than 14 V at the 99.997% level (equal to 30 ppm of the population exceeding 14 V, equivalent to +4
sigma point of a normal distribution). In Figure 11, extrapolating the thyristor data trend to the 99.997% level
indicates a maximum breakdown time, t
(BR)
, of 0.5 µs. Figure 12 shows that increasing the temperature up to
85°C increases the thyristor peak limiting voltage by 2.4%, giving a maximum 85°C peak limiting voltage of
1.024x(-50-14) = -65.5. Over the -40°C to 85°C temperature range the TISPPBL2S is specified to have a
maximum V
(BO)
value of -70 V and a breakdown time, t
(BR)
, of 1 µs.
limiting voltage (Peak Forward Recovery Voltage V
FRM
) is less than 6 V, and this value includes the 2 V of
magnetically induced noise in the probe. Figure 9 shows that extrapolated 99.997% level is about 5.5 V. In
time, t
FR
, of 0.1 µs. Figure 12 indicates that there is about a 10% uplift by increasing the temperature to 85°C.
This gives a maximum 85°C peak limiting voltage of 1.1x(5.5) = 6.1 V. Over the -40°C to 85°C temperature
range, the TISPPBL2S is specified to have a maximum V
FRM
value of 8 V and a maximum forward recovery
time of 1 µs.
Diodes do not switch to a much lower voltage like thyristors, so the diode limiting voltage applies for the whole
impulse duration. Forward voltages of 1 V or less are normally considered safe. Figure 10 shows that the
lowest current 1 V condition occurs at -40°C with a current of 0.3 A. When the TISPPBL2S is tested with the
rated 10/1000 impulse it would take about 8 ms for the current to decay from 30 A to 0.3 A. Over the -40°C to
85°C temperature range, the TISPPBL2S is specified to have a V
F
below 1 V within 10 ms.
SLIC protection requirements
This clause discusses the various requirements of the Ericsson Components SLICs detailed on the first page
of this data sheet and compares these to the TISPPBL2S protector parameters. Some SLICs are rated for
0°C to 70°C operation, others for -40°C to 85°C operation. The TISPPBL2S protector is specified for -40°C to
85°C operation and so covers both temperature ranges.
normal operation
Depending on the SLIC type, the maximum SLIC supply voltage rating (V
Bat
) will be -70 V, -80 V or -85 V. The
-85V rating of the TISPPBL2S gate-cathode (V
GKRM
) matches the highest SLIC voltage rating.
To restore normal operation after the TISPPBL2S has switched on, the minimum switch-off current (holding
current I
H
) needed is equal to the maximum SLIC short circuit current to ground (d.c. line current together
with the maximum longitudinal current). For the SLICs listed on the first page of this data sheet, the
TISPPBL2S minimum holding current of 140 mA will ensure switch-off after an overvoltage.
overvoltage protection
Ericsson Components specify SLIC withstand capability as a series of stress-time values. Figure 15 shows
the voltage withstand limits of the PBL 3762A SLIC.
In the positive polarity, the PBL 3762A RING or TIP voltage must not exceed +15 V. For 250 ns, the PBL
3762A will be able to withstand a voltage between +10 V and +15 V. For 1 µs, the PBL 3796 will be able to
withstand a voltage between +5 V and +10 V. For 10 ms, the PBL 3796 will be able to withstand a voltage
between +2 V and +5 V. To protect against positive overvoltage, the TISPPBL2S positive limiting voltage must
be equal to or less than these voltage values during the specified time periods.
PRODUCT
10
INFORMATION
POINN [ POWER INNOVATIONS LTD ]
