Test set up proposal to detect worst case

AN4299

10/20

DocID024663 Rev 2

3.2

Generator settings

1.

Select “sine wave” and “sweep” mode.

2.

Sweep menu: time = 300 sec, return time = 0, linear, interval = 1 ms

3.

Set Vpp value on the generator to obtain the corresponding voltage injected on the

EUT in case of standard test.

Example: to test in the same condition as the standard at 3 Vrms, you must adjust the

generator voltage to inject 15 Vpp measured on the board with oscilloscope.

Note:

On AFG3102 TEKTRONIX generator, the modulation is not available in sweep mode.

4.

Set the start and end frequencies such that the sweep range does not exceed 60 kHz

for a 300 seconds duration. This recommendation allows to detect worst case level

with sufficient accuracy (typically less than 5 % error).

Note:

An external amplifier might be needed in case the generator would not able to reach the

appropriate injection level.

3.3

Data logging and data processing

Data logging

Example: “MyChannels_Data[x].Delta” and “MyTKeys[(x)].p_Data->StateId”

Data processing

In this example frequency sweep starts at 500 kHz and ends at 550 kHz. Noise level is set

on the generator to 4.6 Vpp (no modulation). Detect out threshold is set to 50, the sensor is

touched and the detection is valid if measured delta is upper 50 else the touch detection is

lost (error is reported). It means that 4.6 Vpp is the limit to avoid detection loss (4.5 Vpp

pass)

As a comparison, IEC61000-4-6 standard recommendation to use 1 % frequency steps

would have lead to explore only ten frequencies in this range, so the chances to detect

worst case would have been very low!

a.

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