Table of Contents
PCB HDMI connectors (Standard, Mini, Micro like plug connectors) are appropriate for various devices. While adding HDMI to a PCB, consideration should be given to the connector type, mounting, and interoperability with other interfaces (such as USB Type-C to HDMI). This guide from elepcb covers several options for HDMI connectors and their use in PCB design.
What's HDMI?
Definition of HDMI
HDMI stands for High Definition Multimedia Interface, and it is an interface standard in digital terms that is in widespread use with the delivery of video and audio.
HDMI Pinouts
The pinouts of the HDMI interface are also specifically defined. For example, the pinout figure of the HDMI 2.1a specification designates the function of every pin and so on. As with the TMDS Clock Pair pin, where Pin10 is positive (P) and Pin12 is negative (N), which performs an important function to identify clock control.
In addition, the CEC function pin is also referred to as Pin13, and the CEC function can be used to offer inter-device control, i.e., the operation of a single remote to control multiple devices in an HDMI connection.
HDMI Electrical Features
There are some electrical specifications for every pin, i.e., signal level, impedance, etc. Every HDMI electrical specification for every pin is listed in the table below.
| PIN NUM | SPECIFICATION |
| 1 | TMDS Data2+ |
| 2 | TMDS Data2 Shield |
| 3 | TMDS Data2- |
| 4 | TMDS Data1+ |
| 5 | TMDS Data1 Shield |
| 6 | TMDS Data1- |
| 7 | TMDS Data0+ |
| 8 | TMDS Data0 Shield |
| 9 | TMDS Data0- |
| 10 | TMDS Clock+ |
| 11 | TMDS Clock Shield |
| 12 | TMDS Clock- |
| 13 | CEC (Consumer Electronics Control) |
| 14 | Reserved |
| 15 | DDC CLOCK |
| 16 | DDC DATA |
| 17 | GROUND |
| 18 | 5VDC |
| 19 | HOT PLUG DETECT |
To preserve signal integrity, a status such as differential impedance of 100 ohms is necessary while transmitting. Without electrical specifications, particularly while transmitting HDMI signals over long distances, signal degradation and distortion will be some of the issues arising, thus degrading the audio and video.
HDMI Versioning
| Version | Key Features |
| Earliest | Supports lower resolution video transmission |
| HDMI 1.4 | Started to support transmission of 4K video |
| HDMI 2.0 | Additional bandwidth in order to stream 4K video at 60Hz. |
| HDMI 2.1 | Much greater bandwidth to transport 8K video signals and greater refresh rate video signals |
HDMI Plug Connectors for PCBs
HDMI plug connectors are of different sizes ranging from Standard, Mini to Micro HDMI. They are for different purposes based on size constraint and requirement for performance.
Standard HDMI (Type A)
It is the most common HDMI connector, utilized in televisions, monitors, home theater systems, and game consoles. It can support high-definition video and audio and is highly compatible with all peripherals.
Mini HDMI (Type C)
Having the advantage of state-of-the-art technology to utilize on small electronic gadgets, the connector is small in size compared to the Standard HDMI connector but capable of transferring an equal quality of sounds and pictures. Mini HDMI is usually integrated into tablets, portable devices, and digital cameras.
Micro HDMI
(Type D)
Micro HDMI is the smallest of the bunch, typically employed on very thin devices like smartphones and small-form-factor products. Even though it is extremely small in size, it will be able to transfer high definition video.
| TYPE | SPECS | DIMENSIONS | APPLICATION | Transmission Bandwidth |
| Standard HDMI | 19 PIN, Supports high-bandwidth data transfer Typical resolution support: up to 4K (3840 x 2160) at 60Hz or higher | 13.3 mm x 4.45 mm | Projectors, TVs, Bluray players etc. | Up to 18 Gbps (HDMI 2.1) |
| Mini HDMI | 19 PIN, Lower power consumption compared to standard HDMI Moderate bandwidth for smaller devices | 10.42 mm x 2.42 mm | Tablets, some portable media players | Up to 10.2 Gbps (HDMI 2.0) |
| Micro HDMI | 19 PIN, Designed for very small devices Limited in power and bandwidth capabilities | 6.4mm x 2.8 mm | Digital Cameras, some small handheld devices | Up to 5 Gbps (HDMI 1.4) |
Types of HDMI Mounting Options
Choosing the appropriate mounting option is critical in order to guarantee reliability and lifespan.
Through-Hole Mount
This form of mounting gives maximum mechanical stability with great strength and is therefore perfectly suited for applications where durability is necessary. In this, connector leads are threaded through pre-drilled holes within the PCB and soldered together, providing greater resistance to stress from mechanics as well as external factors.
Surface-Mount (SMD) HDMI Connector
SMT connectors are used for small-sized PCBs when space is precious. SMD connectors are directly soldered to the surface of the PCB rather than being hole-mounted, hence no holes need to be created. This takes up less space and is ideal for light electronic devices that must be portable.
Hybrid Mounting HDMI Connector
This style of mounting combines through-hole and surface-mounting methods for superior durability. Strong mechanical rigidity is attained through this style with minimal utilization of space; hence, it is a better choice for applications where high performance is required.
Design Considerations
of HDMI Connector for PCB
Case1: AMD Radeon RX 6000 Series PCB Design
Design Focus: HDMI 2.1 Signal Integrity and Routing
During the HDMI 2.1 testing, AMD engineers had seen abnormal signal jitter (0.25 UI) in early RX 6000 GPU samples. That was higher than the 0.15 UI threshold laid down in the HDMI CTS 2.1 spec. They looked into it and realized that the problem was inconsistently routed TMDS differential pairs. Those were specified to a ±15 mil tolerance and introduced impedance variation.
Solution: Optimize Differential Pairs
- Intra-pair length mismatch reduced to ±5 mil utilizing Altium Designer’s xSignals toolset.
- Added more ground shielding between the pairs to reduce crosstalk, as validated by ANSYS HFSS simulations.
- Utilized Rogers 4350B laminate (εr=3.48) to maintain 100Ω ±3% differential impedance (as per IPC-2141A).
Results
- Post-optimisation TDR measurements showed impedance variation of less than 5% (as against 12% earlier).
- Eye diagrams at 12 Gbps improved by 40%, meeting HDMI 2.1 compliance.
Case 2: Sony PlayStation 5 HDMI CEC
Design Focus: HDMI Pinout Implementation & ESD Protection
Random failures of HDMI-CEC on early PS5 dev boards. EEVblog reverse engineering identified a PCB short between Pin 14 (CEC) and Pin 17 (DDC_SCL). The short is due to non-compliance with HDMI Licensing’s Class A connector pinout standard.
Solutions: HDMI Pinout Redesign
- Externed pad-to-pad gap to 0.5 mm from 0.3 mm (compatible with JEDEC JESD22-A114F).
- Added guard traces to connect sensitive pins to chassis ground.
Upgrade ESD Protection
- Equipped Bourns CDSOD323-T05LC ESD diodes. They meet the IEC 61000-4-2 Level 4 requirements and put themselves around 1.5 mm from the HDMI connector.
- After-revision ESD testing was a success of ±15 kV air/±8 kV contact discharge levels.
Tips for HDMI Termination Diagram Wiring and Layout
1. Impedance Control
Provide 50Ω (±10%) impedance for single-ended signals and 100Ω (±10%) for differential pairs. Where layer transitions are required, limit impedance variation to <10% and place GND vias close to transition points to offer unbroken return paths.
2. Layer Stackup
Route inner layers with complete reference GND planes first. For surface-layer traces, use ground shielding (0.5mm wide guard traces at 2× line width spacing) with GND via ≤200mil spaced along shielding lines.
3. Differential Signal
Maintain ≥15mil spacing between differential pairs.
Obey 5W rule intra-pair spacing (W = trace width). Tolerance in length matching: ±5mil intra-pair, ≤10mil inter-pair.
Use serpentine tuning with ≥3× line width spacing for minimizing crosstalk.
4. Trace Length
Trace length <5inch (best <3inch). Limit vias to ≤2 per differential pair. Position via away from connectors by at least 1cm and utilize back-drilling process for eliminating stubs.
5. ESD Protection
Place ESD protection devices ≤3mm from HDMI connector (TVS array is recommended). Directly connect protection device ground pins to system ground via dedicated vias (≥0.3mm diameter) without common ground paths.
6. Termination Topology
Implement source termination with π-network (22Ω series resistor + 2.2pF bypass capacitor). Reserve pads for AC coupling capacitors (100nF/0402). On extended lengths, insert common-mode chokes on receiver side.
7. Testability
Provide 0.8mm diameter ICT test points ≥5mm away from the connector, terminated with 45° branch lines. Provide impedance test coupons with 50Ω single-ended and 100Ω differential structures for TDR verification.
8. Others
- All the important parameters must be confirmed with TDR measurements.
- Recommended test frequency range: 100MHz to 4GHz for full HDMI 2.0 compliance testing.
Conclusion
Choosing the appropriate HDMI connector for PCB uses is a function of device requirements, space availability, and mounting needs. HDMI connectors are an integral component of today’s electronics, facilitating effortless transmission of high-definition signals.
For further technical details or customized design inquiries, please contact the ELEPCB engineering team!
FAQs
A1: USB Type C to HDMI adapters and converters are to facilitate the use of Type C supported devices to connect to display equipment that utilizes the HDMI port for the transmission of high definition video and audio. It is high resolution, high speed data transfer and a plug-and-play device. It is suitable for entertainment settings, such as watching movies and playing games on the big screen, and business settings, such as presentations on the big screen.
References
[1] IEEE 930-2021. “Dielectric Material Characterization”. DOI: 10.1109/IEEESTD.2021.9619086
[2] HDMI 2.1 Specification. §6.3.Available: https://www.hdmi.org/spec/hdmi2_1
[3] Sony. US20230198721A1. Layout Modifications. https://patentcenter.uspto.gov/applications/17926644
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