TISP61089A
DUAL FORWARD-CONDUCTING P-GATE THYRISTORS
PROGRAMMABLE OVERVOLTAGE PROTECTORS
JUNE 1999
after the test has ended. The test current levels and their duration are shown in Figure 8. First level tests have
a high source resistance and the current levels are not strongly dependent on the TISP61089A series resistor
value.
Second level tests have a low source resistance and the current levels are dependent on the TISP61089A
series resistor value. The two stepped lines at the top of Figure 8 are for the 25 Ω and 40 Ω series resistor
cases. If the full current-time durations occur the equipment will fail the wiring simulator test. The MDQ 1-6/
10A fusing characteristic is also shown in Figure 8. The TISP61089A series overcurrent protection must
operate before the MDQ 1-6/10A fuses, so this represents another boundary condition in the selection of the
overcurrent protector.
MAXIMUM RMS CURRENT
vs
TIME
AI6XAK
30
20
Ω
Ω
Second Level Tests - 25
Second Level Tests - 40
10
7
5
3
2
MDQ 1-6/10A Fuse
1
0.7
0.5
0.3
0.2
Ω
First Level Tests - 25 & 40
100
0.1
0.01
0.1
1
10
1000
Time - s
Figure 8. ‘1089 MAXIMUM TEST CURRENT LEVEL
Figure 9 summarises these boundary conditions. The highest current levels that can flow are influenced by
the TISP61089A series resistance. After one second the maximum current-time boundary becomes set by
the MDQ 1-6/10A fusing characteristic. Fusible overcurrent protectors cannot operate at first level current
levels.
Figure 9 shows two other curves. The lower one is the TISP61089A rated current. The overcurrent protector
should not allow current-time durations greater than this otherwise the TISP61089A may fail. If second level
failure is acceptable then the overcurrent protector must operate before the TISP61089A package limit is
reached.
The TISP61089A a.c. ratings are worse case values when the device is mounted on the EIA/JESD51-3 PCB
used for measuring thermal resistance. Typical PCBs would give a 25% increase in the rated currents for
periods above 0.1 s.
P R O D U C T
I N F O R M A T I O N
13
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