HDMI Interface Chip Failure Analysis and Improvement Measures
HDMI, short for High Definition Multimedia Interface, is a high-definition multimedia interface. Since its inception, HDMI has undergone multiple version updates. From the initial HDMI 1.0 to the current HDMI 2.1, each update has brought users higher bandwidth, richer functions, and better compatibility. At CES 2025, the HDMI Forum, Inc. officially announced the upcoming release of HDMI standard version 2.2 (Figure 1). The launch of this new HDMI 2.2 standard marks another significant advancement in HDMI technology.

With the increasing demand for 4K/8K ultra-high-definition video transmission, the reliability of the HDMI interface, as the mainstream digital audio and video transmission interface, faces severe challenges. Statistics show that approximately 35% of HDMI interface failures in the consumer electronics field are caused by electrostatic discharge (ESD) and surge impacts. This type of electrical overstress (EOS) damage directly affects the lifespan of equipment and user experience.

Figure 1. HDMI 2.2 Standard Launched in 2025
1. The coupling energy of transient pulses in the user's mains power environment is conducted to the next stage circuit (MCU/IC) through the LDO and DC-DC chips between power supplies.

2. Different designs of the Y capacitors in the device's switching power supply, the voltage difference between the power supply GND and GND between devices, and the transient current discharge caused by plugging and unplugging under energized conditions.

During the project R&D and testing verification phase, EMC environmental testing is essential. Most products meet the overall system testing requirements for ESD and power surge; however, surge protection for signal lines has not received sufficient attention. Overseas manufacturers have in-house test voltage requirements for surge testing of HDMI/DP/USB signals, and domestic manufacturers are gradually following suit. Looking at the voltage and current waveform durations from the IEC61000-4-5 standard (Figure 2), both voltage and current waveforms are at the microsecond (µs) level, and the discharged energy is far greater than the nanosecond (ns) level ESD energy. This is also more easily observed in the EOS (Electronic Optical Array) damage phenomenon.

Figure 2. IEC6100-4-5 Current and Voltage Test Waveforms

Response Time
Under normal operating conditions, surge protection devices will not activate. They only activate when an external transient pulse reaches the device's trigger voltage. Therefore, the longer the response time, the longer the electronic device is exposed to voltage spikes, and the higher the risk to the IC. Different chip structure interface designs will result in slightly different response times; the ideal response time is less than 1ns.

Clamping Voltage
Clamping voltage is the voltage drop across the protection device after the current is discharged. The lower the clamping voltage, the better the protection level for the next-stage chip or circuit. You will find that the clamping voltage of varistors or TVS made of polymer materials on the market can be as high as tens of V, while the voltage of protection devices manufactured using semiconductor processes will be closer to the maximum voltage of the protected signal, providing better protection.

Energy Absorption/Dissipation
This can be understood as how much surge energy the protection device can absorb. Ipp is an important parameter for testing the current-carrying capacity of ESD protection devices. The higher the Ipp number, the stronger the device's ability to absorb transient current.

Parasitic Capacitance
In relatively high-speed applications like HDMI/DP/USB, larger parasitic capacitance values  on the PCB or electronic components result in longer rise and fall edge delays, posing a signal quality risk when testing eye diagrams with a signal analyzer. The parasitic parameter requirements for protection devices vary under different speed conditions, so special attention must be paid during selection.

TDR Impedance Testing
TDR testing is currently mainly used for testing the impedance of PCB (Printed Circuit Board) signal lines and components, such as single-ended signal lines, differential signal lines, and connector cables. HDMI differential impedance control requires 100Ω ± 10%. Designs aim for minimal impedance impact from ESD devices. TDR assessment of the impedance of ESD protection devices inserted into the PCB is an important indicator of signal requirements. HDMI devices typically use through-hole packages (Figure 3: DFN2510-10L through-hole layout) to reduce impedance abrupt changes caused by PCB layout.

Figure 3: DFN2510-10L Through-Layout Diagram

For ESD devices with high surge protection capabilities for signal lines, this reduces HDMI interface chip failure issues and minimizes quality problems caused by customer returns. Table 1 shows the parameters and surge capability evaluation results of the HDMI interface protection scheme.

Table 1: HDMI Application ESD+Surge Protection Scheme

Summary: Surge testing helps ensure system resilience and reliability. By performing surge testing on the system, you can identify and mitigate potential vulnerabilities or weaknesses in the end system that could lead to failures during voltage spikes or surges.