AN1213 Datasheet, PDF (1/7 Pages) STMicroelectronics – OUTPUT PROTECTION CHARACTERISATION

AN1213
APPLICATION NOTE
TDE1707 NOISE IMMUNITY, SHORT CIRCUIT AND REVERSE
OUTPUT PROTECTION CHARACTERISATION
by Matteo Uccelli
The TDE1707 is a power switch ( I.P.S) especially dedicated to proximity detectors. For the characteristics
of the I.P.S. please refer to the data sheet and AN485.
Since the device operates in Industrial environment, it is very important a good noise immunity. The overload
(up to short circuit) and the output reverse connection hardiness are also key point for a device used in this
applications.
EMC testing.
This Evaluation section describes the noise immunity results. For reference, the test has been done as compar-
ison between the TDE1707-B , improved version and the previous one (Old version).
All of the statements regarding burst immunity refer to measurements done in ESALI (European System Appli-
cation Lab Industrial).
The application laboratory is provided with an appropriate testing bench realised basing on directives contained
in IEC 801/4 normative.
The correlated instrumentation consists of :
- Key Tek ( Thermo Voltek ), CE MASTER EMC immunity test system : surge and burst generator.
- Tektronix TM502 : current probe
- GOULD Data SYS 944 MHz - 500 Ms/sec : digital storage oscilloscope
- Laboratory Power Supply PS-2403 : power supply
The behaviour of the device was monitored with a current probe on the load, which seems to have less influence
on the measurements. Anyway it is important to pay attention because even when using a current probe it is
really easy to couple additional noise, and of course the result consists in the achievement of lower immunity
levels than the right ones: the fast transients should be coupled only thanks to the capacitive coupling clamp.
For the same reason caution is mandatory regarding the power supply: this one should not be directly affected
from the burst generator . Additional coupling becomes easier and easier as the burst voltage increases: par-
asitic antennas becomes more efficient.
Table 1. IEC 801/4, limiting values of burst impulses
severity
test voltage on signal line
4
2kV
3
1kV
2
0.5kV
1
0.25kV
Testing configuration:
Old ( TDE 1707) and new ( TDE 1707 Rev. B ) silicon have been tested and compared regarding fast transient
( burst ) immunity. This testing was performed on several layouts taking care to operate in the same test con-
ditions.
December 1999
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