TOELLNER Electronic Instrumente GmbH
8
2.3.3
E-13, interruption of ground pins
Also for the interruption of a ground pin, a signal line switch of the TOE 9260 is used. Such a
signal line switch is applicable for a ground current up to 1 A.
If up to 2 A have to be switched, two signal line switches can be paralleled. It is not
recommended to operate more than two switches in parallel. With three or four switches in
parallel the timing requirements of the LV 124-2013 cannot be fulfilled with a 1 k
Ω
reference
resistor.
Fig. 4 shows the test assembly with use of one of the signal line switches of the TOE 9260.
Fig. 4:
Test assembly for LV 124, E-13; interruption of a ground pin
2.3.4
E-13, interruption of ground pins
‒
reference measurements
This section applies to LV 124, version 2013 only. That standard requires reference
measurements before an interruption test is carried out with the DUT. Such a reference
measurement gives proof of the slew rate of the switching operation. For the reference
measurements of the E-13 test the DUT is replaced by a reference resistor of 1
Ω
± 5 %
resp. 1 k
Ω
± 5 % of low parasitic inductance.
To avoid the addition of too high cable inductivity, the reference resistor shall be connected
close to the signal line switch by closely spaced wires. The switchable reference resistor
TOE 9260/104 may be connected to power source and signal line switch by provided
suitable cables.
Due to the 1 A current limit of a signal line switch, the measurement with the 1
Ω
resistor
shall be carried out at a voltage of 1 V as shown in Fig. 5. Applying such a low voltage level
instead of the actual voltage of the control unit has no significant influence on the timing of
the measured waveform. Reference measurements with the 1 k
Ω
resistor can be executed
with the same voltage as the normal DUT operation voltage.
Note
If the applied power supply has an internal capacity between its minus terminal and earth,
the oscilloscope resp. data logger must not earth the minus terminal of the reference
resistor. A differential probe or an isolating transformer for supplying the oscilloscope resp.
data logger shall be used in this case. Otherwise a capacity appears across the signal line
switch, and the switching timing is slowed down, especially at small load currents as in
case of the 1 k
Ω
reference resistor.
