ADN4620
Recommended for New Designs
The ADN4620/ADN4621 are dual-channel, signal isolated, low voltage differential signaling (LVDS) buffers that operate at up to 2.5 Gbps with very low jitter...
Datasheet
ADN4620 on Analog.com
ADN4621
Recommended for New Designs
The ADN4620/ADN4621 are dual-channel, signal isolated, low voltage differential signaling (LVDS) buffers that operate at up to 2.5 Gbps with very low jitter...
Datasheet
ADN4621 on Analog.com
ADN4622
Recommended for New Designs
The ADN4622/ADN4624 are quad-channel, signal isolated, low-voltage differential signaling (LVDS) buffers that operate at up to 2.5 Gbps with very low jitter...
Datasheet
ADN4622 on Analog.com
ADN4624
Recommended for New Designs
The ADN4622/ADN4624 are quad-channel, signal isolated, low-voltage differential signaling (LVDS) buffers that operate at up to 2.5 Gbps with very low jitter...
Datasheet
ADN4624 on Analog.com
ADUM1252
Recommended for New Designs
The ADuM1252 offers two bidirectional, open-drain
channels for applications, such as I2C, that require data
to be transmitted in both directions on the...
Datasheet
ADUM1252 on Analog.com
ADuM4070
Production
The ADuM4070 is a regulated DC/DC isolated power supply controller with an internal MOSFET driver. The DC/DC controller has an internal isolated PWM feedback...
Datasheet
ADuM4070 on Analog.com
ADUM321N
Recommended for New Designs
The ADuM320N/ADuM321N are dual-channel digital isolators based on Analog Devices, Inc., iCoupler® technology. Combining high speed, complementary metal...
Datasheet
ADUM321N on Analog.com
What does galvanic isolation have to do with everyday interfaces like HDMI, USB, MIPI, etc.? At first glance, it may not seem like much. Yet understanding this relationship can unlock value across diverse applications, from digital healthcare to industrial automation.
So far in this blog series, we’ve selected a gigaspeed isolation device and associated power solution. Then we optimized the design using the LTSpice tool from Analog Devices, Inc. (ADI). Now we will see how the ADN4620, ADN4621, ADN4622, and ADN4624 isolated LVDS 2.5Gbps devices are playing their part in protocol isolation.
Future posts will focus on gigaspeed communication protocols, their applications, and key considerations for isolation. We’ll begin with the HDMI protocol.
High-definition multimedia interface, or HDMI, is a proprietary audio/video interface for transmitting uncompressed video data and compressed/uncompressed digital audio. It is used to connect an HDMI-compliant source device to a compatible monitor, video projector, TV, monitor, etc.
Looking at the HDMI interface, it might not initially be obvious where or why isolation is needed, so let’s think of a hospital setting where a monitor is connected to a patient monitoring system. What would be the isolation requirements for such an interface? In other words, what checks and balances ensure that the interface is connected to (in this case, HDMI) meets the requirements to ensure the safety of the patient, operator, and equipment itself?
This protection is usually highlighted as a Means of Protection for either the Patient (MOPP) or the Operator (MOOP). In a medical setting, equipment in use must meet level 2 MOPP requirements found in the IEC/EN 60601-1 standard to ensure patient and operator safety.
Creepage and clearance are key specifications in IEC/EN 60601-1. Thus, when selecting components for an isolated HDMI solution, it’s important to ensure that all components selected achieve the 1MOPP or 2MOPP requirements of the design.
|
Classification |
Withstand Isolation Voltage |
Isolated Working Voltage |
Creepage & Clearance |
|
1MOPP |
1500Vac |
250Vrms |
4mm |
|
2 MOPP |
4000Vac |
250Vrms |
8mm |
Table 1: IEC 60601-1 Ed. 3.2 en:2020Medical electrical equipment - Part 1: General requirements for basic safety and essential performance CONSOLIDATED EDITION
The HDMI interface consists of signals that require isolation, some traveling at gigaspeed and others at only kilobits per second (Kbps). Transition-minimized differential signals (TMDS) are gigaspeed signals carrying essential video and audio information that must be displayed. Ensuring that nothing impacts these signals is vital… Enter isolation.
Let’s revisit a familiar signal chain (Figure 1). In the second blog of the series, we saw this signal chain in the context of choosing a power solution for HDMI isolation. Now, as we review the HDMI interface signals below, it’s clear that a number must be isolated.
Figure 1: Technical diagram of an HDMI 1.3a isolated design
Each signal has slightly different requirements in terms of speed, but all components must meet the requirements of IEC 60601. The table below demonstrates the creepage and clearance achievable by all components used in Figure 1 and can easily meet the standard’s 1MOPP requirement for 250Vrms.
|
Suggested ADI Components |
Function |
Creepage / Clearance |
|
ADN4624 |
Isolated 2.5Gsps LVDS Isolator |
8.3mm |
|
ADuM1252 |
I2C and general data that need to be isolated |
8mm |
|
ADuM321 |
5.7 kV RMS/3.0 kV RMS Dual Digital Isolators |
8.3mm |
|
ADuM4070 |
Isolated Switch Regulator with Integrated Feedback |
8.3mm |
Table 2 Analog Devices Components used as part of the HDMI Isolated reference design
HDMI transmits 4 differential pairs, and it can take some effort to translate these signals to a level where they can be isolated and back again. ADI’s isolated products are equipped to handle this, along with other elements of the protocol that need to be isolated such as hot plug detection, display data channel information, and some control signals.
This blog covered some of the main considerations for isolating HDMI signals. Next time, we’ll see how the AD462x family is contributing to the isolation of PCIe—specifically, industrial automation.
These two circuit notes provide further support for HDMI 1080p/60Hz and HDMI 1.3a, including layout considerations and expected performance in a medical-type application, to help you ensure compliance with the HDMI standard.
Read more from the Gigaspeed Isolation series
