Texas Instruments TIDA-010046, Руководство по конструкции

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Hardware, Software, Testing Requirements, and Test Results
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32 TIDUES1A – October 2019 – Revised February 2020
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EMC Compliant 10/100-Mbps Ethernet PHY Reference Design With IEEE
802.3at Type-1 (
≤ 12.95 W) PoE-PD
In Europe, Comite International Special des Perturbations Radioelectriques (CISPR) and European Norm
(EN) regulations provide the guidelines for EMI testing. For example, CISPR 11 and EN 55011 regulations
apply to scientific and medical products. CISPR 14 and EN 55014 apply to electric-motor-based products,
while CISPR 22 and EN 55022 apply to IT equipment.
This reference design is targeted for information technology equipment product sectors as highlighted in
Table 12 . So, the applicable test standards are CISPR 22 (EN 55022) and FCC Part 15 Subpart B - Class
A and B limits.
Table 12. Main Product Standards for Radiated Emissions
PRODUCT SECTOR
IEC | CISPR
STANDARD
EN STANDARD FCC STANDARD
Vehicles, boats, and
devices with internal-
combustion engines Offboard receivers CISPR 12 EN 55012 —
Onboard receivers CISPR 25 EN 55025 —
Information Technology Equipment (ITE) –
computers, telephones, other telecommunication
products, video camera, multimedia equipment
CISPR 22
CISPR 32 (Latest)
EN 55022
EN 55032 (Latest)
Part 15
Industrial, Scientific, and Medical (ISM) equipment CISPR 11 EN 55011 Part 18
Household appliances, electric tools, and similar
apparatus
CISPR 14-1 EN 55014-1 —
Luminaires, lighting equipment CISPR 15 EN 55015 Part 15, Part 18
Equipment with no
product-specific
standard Light industrial IEC 61000-6-3 EN 61000-6-3 —
Heavy industrial IEC 61000-6-4 EN 61000-6-4 —
The radiated emissions maximum measurement frequency is chosen based on the highest frequency of
the internal clock source of the EUT. The following list shows the clock source used in the reference
design on the PD side board (DUT):
• TPS23755 PoE-PD DC/DC switching frequency = approximately 500 kHz
• XTAL1 = 25 MHz for DP83825I
• REF CLOCK OUT = 50 MHz (Used for MAC interface; all RMII signals are disabled in this case)
• XTAL2 = 4 MHz for MSP430
Therefore, the measurement frequency band that is applicable for radiation testing is from 30 MHz to 1
GHz as highlighted in
Table 13 .
NOTE: Since this reference design does not have a MAC, any activity on the RMII (including 50-
MHz reference clock output) was disabled during the radiated emission testing.
Table 13. Radiated Emissions Maximum Measurement Frequency
PRODUCT SECTOR
IEC | CISPR
STANDARD
EN STANDARD FCC STANDARD
Vehicles, boats, and
devices with internal-
combustion engines Offboard receivers CISPR 12 EN 55012 —
Onboard receivers CISPR 25 EN 55025 —
Multimedia equipment CISPR 22 EN 55022 Part 15
ISM CISPR 11 EN 55011 Part 18
Household appliances, electric tools, and similar
apparatus
CISPR 14-1 EN 55014-1 —
Luminaires, lighting equipment CISPR 15 EN 55015 Part 15, Part 18
Equipment with no
product-specific
standard
Commercial and light
industrial
IEC 61000-6-3 EN 61000-6-3 —
Heavy industrial IEC 61000-6-4 EN 61000-6-4 —