ST ST7538Q, Примечание к применению, Страница: 31 / 56

AN2744 Board description
31/56
5.2 Conducted disturbances
5.2.1 Conducted emissions
The EN50065-1 standard describes test setup and procedures for this kind of test.
The measures have been done with 220 VAC mains voltage. The test pattern consists of a
continuous transmission of a fixed tone at a frequency of 70.8 kHz (72 kHz center frequency
minus half the FSK frequency deviation, in this case 2400 Hz) which corresponds to a
symbol "1".
The output signal measured at the artificial network has a value of 120 dBµV rms, which
means a 2 V rms signal on the mains output of the board.
The spectrum analyzer performs a peak measure instead of a quasi-peak measure. For
continuous sinusoidal signals, the two types of measurement give the same result.
Figure 25. Measured input impedance magnitude of the coupling interface in Tx mode for the
86 kHz channel (typical curve)
1
10
100
1000
1E+04 1E+05 1E+06
Freq (Hz)
Impedance
mod
u
lus (
Ω
)
EN50065 EN50065 - - 7 7
1
10
100
1000
1E+04 1E+05 1E+06
Freq (Hz)
Impedance
mod
u
lus (
Ω
)
EN50065 EN50065 - - 7 7