CRD-4525-D1 Cirrus Logic Inc, CRD-4525-D1 Datasheet - Page 30

• Manufacturer Part Number: CRD-4525-D1
• Description: Audio Modules & Development Tools Eval Bd PWM Contrlr+ PwrStg_4Lyr 1oz Cu
• Manufacturer: Cirrus Logic Inc

Specifications of CRD-4525-D1

• Description/function: Audio Amplifiers
• Product: Audio Modules
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

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10.ELECTROMAGNETIC COMPLIANCE
The electromagnetic interference (EMI) performance of the CRD4525-Q1 system has been tested for electromag-
netic compliance (EMC) according to the FCC Class B Part 15 and CISPR22 standards for radiated emissions. The
test results show that the CRD4525-Q1 reference design complies with both of these standards.
For optimal EMI performance, all printed circuit boards (PCB’s) implementing the CS4525 device should be de-
signed to match the PCB layout of the CRD4525-Q1 as closely as possible. In particular, the designer should take
care to make the VP power input and PWM output filter section of the design, including component placement and
trace routing, identical to that of the CRD4525-Q1 board.
10.1
EMI Testing Procedures
The purpose of radiated emissions testing is to ensure that the equipment under test (EUT) does not pro-
duce a level of EMI that would interrupt the normal operation of other devices or systems within close prox-
imity to it.
To measure the EMI levels, the EUT and associated auxiliary equipment are placed into operation on top
of a non-conductive table inside of an electromagnetically isolated chamber, as shown in
table is rotated 360°, near field antennas record the amount of noise radiating from the EUT in the frequency
range of 30 MHz to 1.0 GHz. These near field antennas (and associated electronics) scan and capture the
EMI levels at various antenna heights and orientations (vertical or horizontal), relative to the EUT.
The EMI data from these scans are combined to create a plot of the maximum levels of noise across all
antenna heights and table rotation. The plots gathered from this procedure are called “Peak Scans”. A set
of peak scans (vertical and horizontal) is created for each possible operating mode, i.e. input configuration,
output configuration, etc. The operating mode that produces the peak scans with highest levels of EMI is
then evaluated more closely through the gathering of quasi-peak data.
Quasi-peak data is gathered by measuring the actual power content of the EMI detected during the peak
scan procedure. Once this quasi-peak data has been recorded, it is compared against the limits of the ap-
plicable EMC standard to determine if the EUT is in compliance with the standard. In the case of the
CS4525, these limits are defined by the FCC Class B Part 15 and the CISPR 22 EMC standards.
80 cm
EUT
Turntable
Non-Conductive Table
Figure 21. Test Facility Setup
Test Distance
Ground Plane
1 to 4 meters
Coaxial Cable
CRD4525-Q1
Figure
DS804RD4
21. As the