adm489ar-reel7 Analog Devices, Inc., adm489ar-reel7 Datasheet - Page 13

• Manufacturer Part Number: adm489ar-reel7
• Description: Full-duplex, Low Power, Slew Rate Limited, Eia Rs-485 Transceivers
• Manufacturer: Analog Devices, Inc.

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
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.
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).
10dB/DIV
Figure 27. Driver Output Waveform and FFT Plot Transmitting at 150 kHz
100
0%
90
10
0
Field Strength
1
3
10
500kHz/DIV
5MHz
Rev. D | Page 13 of 16
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.
80
70
60
50
40
30
20
10
0
0.3
Figure 28. Conducted Emissions Test Setup
DUT
log FREQUENCY (0.15–30) (MHz)
0.6
Figure 29. Conducted Emissions
1
SPECTRUM
ANALYZER
LISN
36
ADM488/ADM489
PSU
10
30
LIMIT