Deploying USB, HDMI and DisplayPort Bus Powered Solutions in A/V System Design

In today's A/V industry it's common to design, install and maintain a system that relies on other devices, either farther upstream or downstream in the system, for operating power. HDMI signal-sensing auto-switches, DisplayPort VGA adapter dongles and the embedded media converters in RapidRun Optical cables are just a few examples of common bus powered A/V solutions. Sometimes these devices rely on the power supplied through the signal connection, such as the bus found on pin 18 of the HDMI connector. Sometimes there is an auxiliary USB connection that is used solely to source power from a convenient display, source device or stand-alone power source.

It has never been more important to have a clear understanding of the limitations of various common bus powered devices. Interactive video panels rely on USB connectivity. Auto-switching solutions rely on power delivered by the video source. Digital-to-analog converters (DACs), media converters and signal extenders embedded in cables and termination boxes often depend solely on the power supplied by the video or audio source. Do you know that your system will perform, or are you just hoping it will? This course will help you avoid the most common pitfalls of bus powered A/V solutions and ensure that your system delivers quality, dependable performance.

Transcript

1. PRODUCT LINE A/V Design and Integration With A/V Application And Installation Of USB, DVI-D, HDMI, DisplayPort And Thunderbolt Enabled Systems Bus Powered Solutions Your Presenter Is: Joseph D. Cornwall, CTS-D Technology Evangelist
2. PRODUCT LINE An education isn't how much you have committed to memory, or even how much you know. It's being able to differentiate between what you do know and what you don't. - Jacques Anatole Francois Thibault
3. PRODUCT LINE Our Agenda What Is Bus Power? Common Connectivity Considerations Working With USB Solutions Working With HDMI Solutions Working With DisplayPort++ Solutions Conclusions
4. PRODUCT LINE What Is A Bus Powered Solution? •The term bus describes an electrical connection between a host and a set of devices attached to and dependent upon the host •Attached devices are called nodes •Serial buses send information one bit after another over a single pathway •Parallel buses communicate over discrete connections, typically equal to word length • When the signal bus also provides operating power for the node, it is considered a power bus
5. PRODUCT LINE What Kind Of Power? Alternating current (AC) The flow of charge periodically reverses direction Typically a sine wave Direct current (DC) Flow of charge is unidirectional Referenced to a constant, zero-frequency plane DC voltages can vary over time
6. PRODUCT LINE How Much Power Does A Laptop Supply? Modern laptops use Lithium Ion batteries Batteries contain a number of cells in a series/parallel 'string‘ Charging voltage is typically more than the terminal voltage Lithium Ion cells have 3 volt terminal voltage (4.2V charging) 3 cells in series (3S) = 9v 4 cells in series (4S) = 12v 6 cells in 2 parallel strings of 3 (2P3S) = 9v 8 cells in 2 parallel strings of 4 (2P4S) = 12v
7. PRODUCT LINE What Does G. S. Ohm Say About This? Ohm’s Law is an empirical law that states current is approximately proportional to electric field 5 meters of 32AWG copper wire will add 5.4Ω in series with the load USB @ 200mA = -1.08 volt A loss of 21.6% DP++ @ 300 mA = -1.62 volt A loss of 54% HDMI @ 50mA = -.27 volt A loss of 5.4% Voltage tolerances in devices are typically specified at +/- 5%
8. PRODUCT LINE Why Does This Matter? Hot plug detect is a signal that informs the source that a sink (display or load) is connected Source provides +5V to the sink, which the sink sends back to the source as an assertion voltage Repeaters and switchers may be required to pass a hot plug pulse to an upstream device
9. PRODUCT LINE What Can Go Wrong? Detecting proper voltages is the core of the hardware “handshake” Hot Plug connection detect Plug and Play EDID exchange Content protection HDCP key authentication and exchange When proper voltages are not present in a connected system Complete loss of picture is typically hot plug related Distorted video may be an EDID related issue Flashing images are often indicative of HDCP problems
10. PRODUCT LINE BUS POWER AND USB Global Industry Analysts, Inc. predicts sales of USB 3.0 enabled devices will top 3 billion in 2018 with a peak CAGR approaching 80% in some markets!
11. PRODUCT LINE USB Is The Universal Battery Existing USB technology specifies a 5V (+/-5%) power supply In USB, power is delivered in quanta of unit loads Single unit load in enhanced USB 3.0 is 150mA High-power devices draw up to the maximum number of unit loads permitted (6 unit loads) USB 1.1, 2.0 and 3.0 all treat power similarly and compatibly Minimum operating voltage of 4.4 V in USB 2.0, and 4 V in USB 3.0.
12. PRODUCT LINE USB Battery Charging Specification (2007) Standard USB com ports require the device to negotiate power demands with the host after the first unit load is allocated Charging downstream port (CDP) can supply currents between 500 mA and 1.5 A without the digital negotiation May supply up to 500 mA at 5 V Up to the rated current at 3.6 V or more Drops output voltage if the device attempts to draw more than the rated current USB specs limit inrush current Standard USB 2.0 A-connectors are rated at 1.5 A
13. PRODUCT LINE USB Power Standards Chart
14. PRODUCT LINE Typical USB Power Exchange 1. Hub is assigned 100mA to start 4. If the hub is bus powered it will “negotiate” with the source for additional unit loads 2. When connected to the hub, the function is assigned 100 mA 3. If the function needs more than 100mA (1 unit load), the function will negotiate with the hub for additional unit loads Five meters maximum Five meters maximum • “Sleeping” inactive devices are pulling power to facilitate “instant on” • Bus powered hubs are consuming at 1 unit load for operational power
15. PRODUCT LINE Analyze A Simple Classroom System If passive, -100mA Bus Powered -100mA Hidden Passive Hub -100mA How much power does this device require? What other devices are connected to the IWB and how much power to they require? • How confident are we that this simple classroom system will work? • What should we consider in this design?
16. PRODUCT LINE A More Sophisticated Installation Powered Hub Powered Extender All functions connected to hub can access full power Full power is delivered to interactive frame for confident performance Interactive frames universally require high power, 500mA Each port can supply up to 900mA for charging and operation We’ve designed this system to work!
17. PRODUCT LINE BUS POWER AND HDMI “There are a lot of things wrong with HDMI. For one, the technology keeps pushing the limits of what a standard non-active cable can handle - this is especially true when HDMI is used over long distances.” – Audioholics Magazine
18. PRODUCT LINE HDMI Pin Out
19. PRODUCT LINE HDMI Power HDMI specification requires all source devices to provide at least 55mA on the 5V line Located on Pin 18, must be 4.7 to 5.3V 55mA is not enough current to operate most HDMI accessory devices, but in common practice most source devices provide more current on the 5V line than the HDMI specification requires Design considerations should be based on specification, not “common practice” HDMI power is intended for hot plug detection HDMI source provides +5V to the sink which the sink sends back as the hot plug assertion voltage on pin 19 HDMI power is used for reading EDID
20. PRODUCT LINE Active HDMI Over Copper Directional, active cables that incorporate a chip set to pre-equalize the signal so that it maintains eye pattern fidelity Example used - Redmere MEA1689 Chipset Bus powered solution – no external power supply option. Powered by HDMI bus. Circuit is limited to 3.4Gbps per channel (1080p) Chipset is embedded at the sink connection “Stacking” an active, embedded chip with an external bus-powered device (a switch, for example) may cause system instability If embedded chip is at the sink, voltage drop over the length of the cable may still be an issue Picture Courtesy of www.Audioholics.com
21. PRODUCT LINE HDMI Embedded Media Converters An embedded media converter is a chip that fundamentally changes the signal to leverage a completely different optical or electrical connection topology Some examples include RapidRun Optical, AOC, Celerity Optical Gateway Often these systems will leverage a USB power connection Transmitter function may be powered by the HDMI or DisplayPort bus “Stacking” should be avoided If copper is not co-run with the optical channel the power must be sourced at both the source and sink components Example shown, RapidRun Optical
22. PRODUCT LINE How Can I “Fix” An HDMI Power Issue? HDMI has a long history of “challenges” in installation Because of this there is a demand for solutions to common problems Many installation failures associated with sagging power and/or under-current situations can be addressed with a voltage inserter However, multiple breaks in HDMI connection can induce distortion in the eye pattern. It’s important to analyze connection segment lengths.
23. PRODUCT LINE BUS POWER AND DISPLAYPORT “I hope more display manufacturers adopt this standard, because DisplayPort rocks.” - Michael Brown Senior Editor, PCWorld
24. PRODUCT LINE DisplayPort Is The VGA Of The 21st Century!
25. PRODUCT LINE DisplayPort Power DisplayPort is designed to replace older standards like DVI and VGA Hot plug detect on pin 18, power on pin 19 (return) and 20 for DisplayID/DDC Runs at 3.3 volts @ 500 mA for maximum utility in mobile devices Thunderbolt combines PCI Express and DisplayPort into one protocol Uses the same connector as Mini DisplayPort (MDP) Designed so all peripherals can driven off of the same bus Up to 18 volts @ 550 mA (9.9 watts)
26. PRODUCT LINE DisplayPort Pin Out Aux Lane 0 Lane 1 Lane 3 Hot Plug Power Retur n +3.3V @ 500mA Confi g Lane 2
27. PRODUCT LINE
28. PRODUCT LINE Thunderbolt & Mini-DP DisplayPort Power Hot Plug Detect
29. PRODUCT LINE Potential DisplayPort Issues DisplayPort exhibits similar potential for Hot Plug Detect or DDC/EDID communication failure as other connection standards With the added complexity that the sink must pull voltage up to 5V from 3.3V DisplayPort to VGA adapters include a D/A chip set Chip set requires power to operate and this may affect battery life and/or link length
30. PRODUCT LINE IN CONCLUSION… “A conclusion is the place where you got tired of thinking.” − Harold Fricklestein
31. PRODUCT LINE What We’ve Learned… • USB operates at 5 volts and 500mA per port • USB, as implemented today, delivers power in quanta of unit loads where each unit load = 150mA • The power bus in DVI-D, HDMI, DisplayPort and Thunderbolt connections is primarily used for Hot Plug Detect and to read EDID information • DVI-D and HDMI operate on a 5 volt bus and are designed to deliver at least 55mA of current • DisplayPort operates on a 3.3 volt bus and is designed to deliver 500mA • Thunderbolt has an operating voltage to 18 volts @ 550mA • DisplayPort and HDMI/DVI-D bus supplies were not envisioned as power supplies for peripherals “Live long and prosper.”
32. PRODUCT LINE Questions?