ADM202E/ADM1181A
IEC1000-4-3 RAD IATED IMMUNITY
current glitch between VCC and GND which results in con-
ducted emissions. It is, therefore, important that the switches in
the charge pump guarantee break-before-make switching under
all conditions so that instantaneous short circuit conditions do
not occur.
IEC1000-4-3 (previously IEC801-3) describes the measurement
method and defines the levels of immunity to radiated electro-
magnetic fields. It was originally intended to simulate the elec-
tromagnetic fields generated by portable radio transceivers or
any other device which generates continuous wave radiated
electromagnetic energy. Its scope has since been broadened to
include spurious EM energy which can be radiated from fluores-
cent lights, thyristor drives, inductive loads, etc.
T he ADM202E has been designed to minimize the switching
transients and ensure break-before-make switching thereby
minimizing conducted emissions. T his has resulted in the level
of emissions being well below the limits required by the specifi-
cation. No additional filtering/decoupling other than the recom-
mended 0.1 µF capacitor is required.
T esting for immunity involves irradiating the device with an EM
field. T here are various methods of achieving this including use
of anechoic chamber, stripline cell, T EM cell, GT EM cell. A
stripline cell consists of two parallel plates with an electric field
developed between them. T he device under test is placed within
the cell and exposed to the electric field. T here are three severity
levels having field strengths ranging from 1 V to 10 V/m. Results
are classified in a similar fashion to those for IEC1000-4-2.
Conducted emissions are measured by monitoring the mains
line. T he equipment used consists of a LISN (Line Impedance
Stabilizing Network) that essentially presents a fixed impedance
at RF, and a spectrum analyzer. T he spectrum analyzer scans
for emissions up to 30 MHz and a plot for the ADM202E is
shown in Figure 19.
1. Normal Operation.
S1
S3
2. T emporary Degradation or loss of function that is self-
recoverable when the interfering signal is removed.
V
CC
V+ = 2V
CC
C3
C1
S2
S4
3. T emporary degradation or loss of function that requires
operator intervention or system reset when the interfering
signal is removed.
V
GND
CC
INTERNAL
OSCILLATOR
4. Degradation or loss of function that is not recoverable due to
damage.
T he ADM202E/ADM1181A products easily 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 irradia-
tion.
Figure 17. Charge Pum p Voltage Doubler
ø
1
Table III. Test Severity Levels (IEC1000-4-3)
ø
2
Level
Field Strength V/m
SWITCHING GLITCHES
1
2
3
1
3
10
Figure 18. Switching Glitches
EMISSIO NS/INTERFERENCE
EN55 022, CISPR22 defines the permitted limits of radiated
and conducted interference from Information T echnology (IT )
equipment. T he objective of the standard is to minimize the
level of emissions both conducted and radiated.
80
70
60
50
40
30
20
10
0
LIMIT
For ease of measurement and analysis, conducted emissions are
assumed to predominate below 30 MHz and radiated emissions
are assumed to predominate above 30 MHz.
CO ND UCTED EMISSIO NS
T his is a measure of noise that gets conducted onto the mains
power supply. Switching transients from the charge pump that
are 20 V in magnitude and contain significant energy can lead to
conducted emissions. Other sources of conducted emissions can
be due to overlap in switch on-times in the charge pump voltage
converter. In the voltage doubler shown below, if S2 has not
fully turned off before S4 turns on, this results in a transient
0.3
0.6
1
3
6
10
30
LOG FREQUENCY – MHz
Figure 19. ADM202E Conducted Em issions Plot
REV. 0
–9–
ADI [ ADI ]
