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CISPR 35: Multimedia Equipment – Electromagnetic Compatibility Immunity Requirements
Comprehensive EMC immunity standard for multimedia equipment covering ESD, EFT, surge, conducted RF, radiated RF up to 6 GHz, and power frequency magnetic fields
Introduction to CISPR 35
CISPR 35 is the comprehensive immunity standard for multimedia equipment (MME), superseding CISPR 20 (broadcast receiver immunity), CISPR 24 (ITE immunity), and CISPR 34-1 (broadcast receiver immunity). Published in 2016, CISPR 35 provides a unified set of immunity requirements for all multimedia equipment including personal computers, servers, printers, televisions, audio equipment, radio receivers, game consoles, and streaming devices. The standard covers the full range of electromagnetic disturbances: electrostatic discharge (ESD), electrical fast transients (EFT), surge, conducted RF immunity (0.15-80 MHz), radiated RF immunity (80-6000 MHz), and power frequency magnetic fields. CISPR 35 represents the culmination of the CISPR standards convergence process, providing manufacturers with a single immunity standard for virtually all consumer and commercial electronic products.
CISPR 35 is the immunity counterpart to CISPR 32 (emissions). Together, CISPR 32 and CISPR 35 form the complete EMC framework for multimedia equipment, replacing the previous patchwork of ITE-specific and AV-specific EMC standards. Manufacturers can now reference just two standards for both emission and immunity compliance.
Immunity Requirements and Test Levels
CISPR 35 specifies immunity test levels that harmonize and slightly extend the requirements of the standards it supersedes. For radiated RF immunity, the standard requires 3 V/m for the 80-1000 MHz range (with 80% AM modulation at 1 kHz) and 3 V/m for 1000-6000 MHz (with PM modulation). Conducted RF immunity requires 3 V (EMF) for the 0.15-80 MHz range. ESD testing requires ±4 kV contact and ±8 kV air discharge. EFT requires ±1 kV on power ports and ±0.5 kV on signal/control ports. Surge requires ±1 kV line-to-line and ±2 kV line-to-ground. A significant advance in CISPR 35 is the introduction of frequency-dependent performance criteria for digital broadcasting and multimedia streaming — recognizing that different types of content (audio-only vs. audio-video vs. data) have different tolerance to interference-induced degradation.
| Immunity Test | Standard Reference | Test Level | Performance Criterion | Applicable Ports |
|---|---|---|---|---|
| Radiated RF (80-1000 MHz) | IEC 61000-4-3 | 3 V/m, 80% AM | A — No degradation | Enclosure |
| Radiated RF (1-6 GHz) | IEC 61000-4-3 | 3 V/m, PM | A — No degradation | Enclosure |
| Conducted RF (0.15-80 MHz) | IEC 61000-4-6 | 3 V (EMF) | A — No degradation | Power, signal, telecom |
| ESD — Contact | IEC 61000-4-2 | ±4 kV | B — Temporary, auto recovery | Enclosure, ports |
| ESD — Air | IEC 61000-4-2 | ±8 kV | B — Temporary, auto recovery | Enclosure, ports |
| EFT | IEC 61000-4-4 | ±1 kV / ±0.5 kV | B — Temporary, auto recovery | Power / signal ports |
| Surge — L-L / L-G | IEC 61000-4-5 | ±1 kV / ±2 kV | B — Temporary, auto recovery | Power ports |
| Power frequency magnetic field | IEC 61000-4-8 | 30 A/m (50/60 Hz) | A — No degradation | Enclosure |
CISPR 35 introduces the 1-6 GHz radiated immunity requirement that did not exist in CISPR 24 or CISPR 20. This extension is driven by the proliferation of wireless communication bands up to 6 GHz (Wi-Fi 6E at 6 GHz, 5G NR bands). Equipment with wireless interfaces operating in these bands must maintain immunity to radiated fields up to 6 GHz.
Engineering Design for CISPR 35 Compliance
CISPR 35 compliance demands a holistic EMC design approach that addresses all immunity phenomena simultaneously. Key design strategies include: (1) Enclosure shielding using conductive gaskets at all seams and apertures, with bonding intervals ≤ λ/20 at 6 GHz (approximately 2.5 mm), providing broadband RF immunity up to 6 GHz. (2) Multi-stage power supply protection: MOV (surge) + gas discharge tube (severe surge) + common-mode choke (conducted RF) + X/Y capacitors + TVS (EFT/surge clamping). (3) Comprehensive I/O port protection: TVS arrays or steering diodes for ESD/surge, common-mode chokes for conducted RF, and integrated filtering for high-speed interfaces using common-mode filter arrays with embedded ESD protection. (4) PCB-level design: continuous ground planes, isolated analog/digital sections, minimal loop areas for high-speed signals, and strategic placement of decoupling capacitors (0.1 µF + 1 nF + 100 pF at each IC power pin).
A particular challenge in CISPR 35 is maintaining immunity performance in products with multiple wireless interfaces (Wi-Fi, Bluetooth, 5G, GNSS). The receiver desensitization (desense) problem — where internal noise from high-speed digital circuits degrades the sensitivity of co-located wireless receivers — must be addressed through physical separation (antenna-to-noise-source spacing > 20 mm), shielding cans over wireless modules, and filtered power supply rails for RF circuits. Pre-compliance testing using a calibrated GTEM cell and ESD simulator during the prototype phase can identify immunity weaknesses before formal laboratory testing, reducing compliance costs by 30-50%.
A well-designed multimedia product — with a fully shielded metal enclosure, multi-stage filtered power supply, TVS-protected I/O ports, separated analog/digital PCB sections, and 6 dB immunity margin — can successfully navigate CISPR 35 certification in a single laboratory visit, avoiding the costly re-test cycles that affect 40% of first-time compliance attempts.
Transition from CISPR 24 and CISPR 20 to CISPR 35
CISPR 35 consolidates and replaces CISPR 24 (ITE immunity) and CISPR 20 (broadcast receiver immunity). Manufacturers transitioning from the earlier standards should be aware of key differences: (1) The radiated RF frequency range is extended to 6 GHz; (2) performance criteria for multimedia functions (audio streaming, video playback, network connectivity) are more explicitly defined; (3) new test configurations for broadcast receiver tuner ports are aligned with CISPR 32 emission test configurations; and (4) the standard introduces requirements for products with multiple operating modes (e.g., a TV that is also a streaming device and a game console). Products previously compliant with CISPR 24 or CISPR 20 should be re-assessed against CISPR 35, particularly for the extended frequency range (1-6 GHz) and the updated performance criteria for digital multimedia functions.
Products that were compliant with CISPR 24 alone may fail CISPR 35 due to the extended radiated immunity range (1-6 GHz) and stricter performance criteria for broadcast receiver functions. A comprehensive gap analysis is strongly recommended before declaring CISPR 35 compliance, especially for products combining ITE, AV, and broadcast receiver functions.
Frequently Asked Questions
Q: Does CISPR 35 apply to all multimedia equipment or only products with broadcast reception?
A: CISPR 35 applies to all multimedia equipment as defined in CISPR 32 — this includes ITE, AV equipment, broadcast receivers, and combined-function devices. Broadcast reception capability is not required for the standard to apply.
A: CISPR 35 applies to all multimedia equipment as defined in CISPR 32 — this includes ITE, AV equipment, broadcast receivers, and combined-function devices. Broadcast reception capability is not required for the standard to apply.
Q: What is the difference between performance criteria A and B in CISPR 35?
A: Criterion A requires no degradation of performance during the test (for continuous phenomena like RF fields). Criterion B allows temporary degradation during the test with automatic recovery after the disturbance ceases (for transient phenomena like ESD, EFT, and surge). Loss of data or permanent degradation is not permitted under either criterion.
A: Criterion A requires no degradation of performance during the test (for continuous phenomena like RF fields). Criterion B allows temporary degradation during the test with automatic recovery after the disturbance ceases (for transient phenomena like ESD, EFT, and surge). Loss of data or permanent degradation is not permitted under either criterion.
Q: How do I test a product that has both AC and DC power inputs?
A> Both power ports must be tested. The AC port is tested per the standard’s AC port requirements, and the DC port is tested per the DC port requirements (typically with a specific CDN or LISN appropriate for the DC voltage and current rating).
A> Both power ports must be tested. The AC port is tested per the standard’s AC port requirements, and the DC port is tested per the DC port requirements (typically with a specific CDN or LISN appropriate for the DC voltage and current rating).
Q: What margin is recommended for CISPR 35 compliance?
A> A minimum of 6 dB margin for RF immunity tests and a 25% margin for transient tests (ESD, EFT, surge voltage levels) is recommended for production equipment to account for component tolerances, manufacturing variation, and environmental factors.
A> A minimum of 6 dB margin for RF immunity tests and a 25% margin for transient tests (ESD, EFT, surge voltage levels) is recommended for production equipment to account for component tolerances, manufacturing variation, and environmental factors.
