ADM488/ADM489

Rev. D | Page 13 of 16

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

Field Strength

1

1

2

3

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.

10

0%

100

90

10dB/DIV

500kHz/DIV

05MHz

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).

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.

DUT

LISN

PSU

SPECTRUM

ANALYZER

Figure 28. Conducted Emissions Test Setup

log FREQUENCY (0.15–30) (MHz)

0.3

0.6

1

36

10

30

80

0

70

40

30

20

10

60

50

LIMIT

Figure 29. Conducted Emissions