ADM488 Просмотр технического описания (PDF) - Analog Devices
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ADM488 Datasheet PDF : 16 Pages
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The ADM488/ADM489 comfortably meet Classification 1 at
the most stringent (Level 3) requirement. In fact, field strengths
up to 30 V/m showed no performance degradation, and error-
free data transmission continued even during irradiation.
Table 9. Field Strengths
Level V/m
1
2
3
Field Strength
1
3
10
EMI EMISSIONS
The ADM488/ADM489 contain internal slew rate limiting to
minimize the level of electromagnetic interference generated.
Figure 27 shows an FFT plot when transmitting a 150 kHz data
stream.
100
90
10dB/DIV
10
0%
0
500kHz/DIV
5MHz
Figure 27. Driver Output Waveform and FFT Plot Transmitting at 150 kHz
The slew limiting attenuates the high frequency components.
EMI is, therefore, reduced, as are reflections due to improperly
terminated cables.
EN55022, CISPR22 defines the permitted limits of radiated and
conducted interference from information technology
equipment (ITE).
ADM488/ADM489
The objective is to control the level of both conducted and
radiated emissions.
For ease of measurement and analysis, conducted emissions are
assumed to predominate below 30 MHz, while radiated
emissions predominate above this frequency.
CONDUCTED EMISSIONS
Conducted emissions are a measure of noise that is conducted
onto the main power supply. The noise is measured using a
LISN (line impedance stabilizing network) and a spectrum
analyzer. The test setup is shown in Figure 28. The spectrum
analyzer is set to scan the spectrum from 0 MHz to 30 MHz.
Figure 29 shows that the level of conducted emissions from the
ADM488/ADM489 is well below the maximum allowable
limits.
SPECTRUM
ANALYZER
DUT
LISN
PSU
Figure 28. Conducted Emissions Test Setup
80
70
60
LIMIT
50
40
30
20
10
0
0.3 0.6 1
36
10
30
log FREQUENCY (0.15–30) (MHz)
Figure 29. Conducted Emissions
Rev. D | Page 13 of 16
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