Transcript
USB Developer Days 2015
USB‐PD Practical Application: Enabling Charge-Through Hubs Terrance Shih Product Manager Taipei, Taiwan November 17 – 18, 2015
November 17 – 18, 2015
USB Implementers Forum © 2015
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USB Developer Days 2015
Session Agenda • Introduction to Multi-Function Docking • Traditional Docking Stations • USB Type-C Advantages • Charge-Through Docks
• Power Budgeting Basics • Self-Powered vs Bus-Powered • Legacy USB Port Considerations • Power Policy
• Practical Charge-Through Hubs • Design Considerations • Protocol Walkthrough • Exception Handling
November 17 – 18, 2015
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USB Developer Days 2015
Multi-Function Docking
• Traditional Docking Stations • USB Type-C Advantages • Charge-Through Scenario
November 17 – 18, 2015
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USB Developer Days 2015
Traditional Docking Stations • Separate Connections for Data, Video, and Power • Data and Video over USB • Dedicated Power Supply
• Simplified Power Budgeting • Fixed Power Supply for either Self-Powered or BusPowered Configurations • Fixed Power and Data Roles
• Used primarily with Notebooks and Tablet PC’s
November 17 – 18, 2015
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USB Developer Days 2015
Traditional Docking Scenario Standard Display USB
HDMI
Dock USB
November 17 – 18, 2015
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USB Developer Days 2015
Traditional Docking Scenario Standard Display USB
HDMI
Dock USB
November 17 – 18, 2015
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USB Developer Days 2015
USB Type-C Advantages • Data, Video, and Power over a Single Connector • Supports Thin & Light Platform I/O Expansion Needs • Enables Single-Connector, Multi-Function Devices
• USB Type-C is Expandable • USB-C is a connector spec and by itself, you only get USB 2.0 and Legacy USB Power • SuperSpeed USB is Optional • USB Power Delivery is Optional • Support for Alt Modes is Optional
November 17 – 18, 2015
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USB Developer Days 2015
Charge-Through Scenario Standard Display
C
Mini Dock
HDMI
C
C USB C
PD
C
PD
November 17 – 18, 2015
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USB Developer Days 2015
Reminder: Be Mindful of User Expectations…
November 17 – 18, 2015
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USB Developer Days 2015
What Could Go Wrong?
November 17 – 18, 2015
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USB Developer Days 2015
“Totally Useless”
November 17 – 18, 2015
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USB Developer Days 2015
Power Budgeting Basics
• Self-Powered vs Bus-Powered • Supporting Legacy USB Ports • Power Policy
November 17 – 18, 2015
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USB Developer Days 2015
Self-Powered vs Bus-Powered • Self-Powered devices draw power from an independent, internal or external power source separate from the USB Bus • Power is limited by the internal or external power supply
• Bus-Powered devices draw power from the USB Bus • Must meet appropriate USB Power Limits • 500mA/900mA for Legacy USB • 900mA/1.5A/3.0A for Type-C Power • Other Voltage/Current Negotiable using USB Power Delivery
• Design Considerations • Do I want to work exclusively in Self-Powered Mode? • In Bus-Powered mode, does the USB bus provide adequate power for desired operation? November 17 – 18, 2015
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USB Developer Days 2015
Bus-Powered Operation • A Straight-Forward Scenario
Standard Display
• Power Source is Fixed • Stay within the Source Limits
• PD Supersedes Power Limits defined by USB 3.1 and USB Type-C Dongle
• Sources can Change Rp in operation so you need to track it
HDMI
• If No PD, then Follow Source Rp
USB C
• Pro Tip: Don’t Rely on 5V @ 3A
November 17 – 18, 2015
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USB Developer Days 2015
Case Study #1
November 17 – 18, 2015
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USB Developer Days 2015
Self-Powered, Fixed Supply • A Straight-Forward Scenario • Budget for system power consumption and charging capabilities • Source Capabilities are PreDetermined
Provides: 5V @ 3A 12V @ 3A 20V @ 3A USB
• Considerations • If the device uses a non-PD AC/DC adapter instead of batteries or a wall plug, consider that users may try to use other adapters… C
November 17 – 18, 2015
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USB Developer Days 2015
Self-Powered, Variable Supply • Source Capabilities? It Depends!
• Deduct System Power Consumption & Power Losses • Advertised Source Capabilities + System Power Consumption cannot Exceed Source Capabilities of the PD Adapter
• Available PD Tools • Get_Source_Cap
• Supplied Voltages @ Currents (7 Combos Max) • Externally Powered? • Peak Current
• Get_Sink_Cap
• Externally Powered? • Operational Current
Provides: 5V @ 3A 12V @ 3A 20V @ 3A
C
PD
Requires 6W Advertises: 5V @ 1.8A 12V @ 2.6A 20V @ 2.7A
Mini Dock
C USB
C
• Capability Mismatch
November 17 – 18, 2015
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USB Developer Days 2015
Case Study #2 Claim: “The Dock has a cable with a male USB-C plug extending from one end that connects to the USB-C port on a MacBook. The other end has a female USB-C jack where the MacBook's power adapter is plugged — powering both the Dock and the MacBook. Advanced USB 3.1 Power Delivery Specification circuitry in the Dock manages the power in and out of the dock, to each of the ports, and to the MacBook.” November 17 – 18, 2015
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USB Developer Days 2015
Case Study #2 Facts: 1) Macbook USB Type-C Power Adapter is rated at 29W 2) USB 3.0 Max Current is 900mA @ 5V, or 4.5W per port 4x Ports = Up to 18W
3) The Hub, Card Reader, and Ethernet controllers also need power, and we still haven’t accounted for the USB-C ports or power losses… November 17 – 18, 2015
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USB Developer Days 2015
Supporting Legacy USB Ports • Standard A USB ports lacks an insertion detection mechanism, and there is no standard method to communicate either source or sink capabilities • USB Battery Charging Specifications define a method for a USB port to advertise that additional current is available using D+/D- pins, but the upper limit is not well defined • It is no practical method to “guess” a device’s power consumption since the amount of current sunk is entirely dependent upon the device • Some USB-powered gadgets only draw Vbus and completely ignore D+/D-
• To avoid over-current conditions, the only method of budgeting power for Standard A USB ports is to account for maximum power consumption! November 17 – 18, 2015
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USB Developer Days 2015
November 17 – 18, 2015
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Power Policy • System Power Policy is the manufacturer’s decision, but having a more flexible approach may give a better user experience • Wide-range voltage input enables charging from more sources • Accepting power from a source that does not provide sufficient power to actually charge the system may still extend system runtime • Devices that do this are available on the market today!
• Prioritize Power based on Intended Use • Example: When attached to an external power source, a Hub with a built-in Battery may determine the Sink Capabilities of the Host to better decide how to charge its internal battery while still supplying power
November 17 – 18, 2015
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USB Developer Days 2015
Power Policy in Action Accepts: Minimum 20V @ 3A C
C
PD
November 17 – 18, 2015
Provides: 5V @ 3A 12V @ 3A 20V @ 3A
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USB Developer Days 2015
Power Policy in Action Needs 2.5W, Advertises: 5V @ 2.5A 12V @ 2.79A 20V @ 2.87A
Required Minimum: 20V @ 3A Rejects 20V @ 2.87A C
Mini Dock
HDMI
Standard Display
C
C
PD
November 17 – 18, 2015
Provides: 5V @ 3A 12V @ 3A 20V @ 3A
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USB Developer Days 2015
Power Policy in Action Needs 8W, Advertises: 5V @ 1.4A 12V @ 2.3A
Required Minimum: 5V @ 1.5A Accepts 12V @ 2.3A C
Mini Dock
HDMI
Standard Display
C USB
C
PD
November 17 – 18, 2015
Provides: 5V @ 3A 12V @ 3A
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USB Developer Days 2015
Smart(er) Power Distribution Gets Sink Cap Advertises: 12V @ 1.25A Consumes 12V @ 1.75A
Operational Power: 15W Accepts 12V @ 1.25A
Portable Powered Hub C
C
PD Out C
In C
C
C
November 17 – 18, 2015
Provides: 5V @ 3A 12V @ 3A
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USB Developer Days 2015
Practical Charge-Through Hubs
• Special Dual Role Ports • Captive Cable vs Receptacle • Re-Regulating vs Passing-Through • Protocol Walkthrough • Exception Handling
November 17 – 18, 2015
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USB Developer Days 2015
Special Dual Role Ports • Sinking DFP • Sub-class of a DRP that is capable of sinking power, but not capable of acting as a device. PD Support is required for Data Role Swap. • A PD Source can be connected to Hub’s Sinking DFP
• Charging UFP • Sub-class of a DRP that is capable of supplying power, but not capable of acting as a host. Operates as a device but not as a host. PD Support is required for Data Role Swap. • Upstream Port of a Hub that can be used to Charge a Device with a Dead Battery
November 17 – 18, 2015
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USB Developer Days 2015
Captive Cable vs Receptacle • Captive Cable • Access to Vconn • Reduced BOM since there is no need for a switch/mux or electronic marker
• Receptacle • Vconn is not passed through the cable • Needs to support reversibility so signal switch is required • Depending on functionality, may need to source Vconn and read electronic marker in the cable
November 17 – 18, 2015
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USB Developer Days 2015
Re-Regulating vs Passing-Through Provides: 5V @ 2.4A 9V @ 2.4A 15V @ 2A
Provides: 5V @ 2.4A 9V @ 2.4A 15V @ 2A
C
PD
Requires 3W Advertises: 5V @ 1.8A 9V @ 2A 15V @ 1.8A
Mini Dock
C
C
PD
Requires 3W Advertises: 5V @ 2.4A 12V @ 2.25A 20V @ 1.35A
C
Mini Dock
C
C
November 17 – 18, 2015
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USB Developer Days 2015
Protocol Walkthrough: Scenario Overview Connect Mini-Dock as a Bus-Powered Device Connect PD Adapter to Mini-Dock Mini-Dock establishes contracts with both the Host and the PD Adapter Mini-Dock Charges the Host C
Mini Dock
C
C
PD
November 17 – 18, 2015
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USB Developer Days 2015
Protocol Walkthrough (1/4): Initial Connection Host
VL100 Mini Dock Connect UFP to Host DFP
Detect Rd on CC Turn on Vbus (5v), Rp = 1.5A Turn on Vconn Send Source_Capabilities Message
Evaluate Source_Capabilities
Request (5V @ 1.5A) Accept
PS_RDY
November 17 – 18, 2015
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USB Developer Days 2015
Protocol Walkthrough (2/4): Connect PD Adapter Host
VL100 Mini-Dock
PD Adapter
Connect to Sinking DFP Detect Rd on CC Turn on Vbus (5V) Rp = 3A
Send Source_Capabilities
Accept
PS_RDY
Evaluate Source_Capabilities Request (5V @ 3.0A)
November 17 – 18, 2015
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USB Developer Days 2015
Protocol Walkthrough (3/4): Power Role Swap Host
VL100 Mini-Dock
PD Adapter
Accept
Turns off Vbus Transitions to Sink, Presents Rd PS_RDY
PR_Swap
PS_RDY Turn on Vbus (5V), Presents Rp @ 900mA
Send Source_Capabilities* * = Derived from PD Adapter
November 17 – 18, 2015
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USB Developer Days 2015
Protocol Walkthrough (4/4): Charge-Through! Host
VL100 Mini-Dock
PD Adapter
Evaluate Source_Capabilities Request (20V @ 2.5A)
Wait Request (20V @ 3A)
Request
Accept
Accept
PS_RDY
PS_RDY Turn On Vbus (20V)
November 17 – 18, 2015
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USB Developer Days 2015
Corner Case: Dead Battery
:(
Host Battery is Depleted, Presents Rd If Mini-Dock is a standard UFP, it won’t be able to provide power! C
Mini Dock
C
C
PD
November 17 – 18, 2015
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USB Developer Days 2015
Corner Case: Dead Battery
:(
Host Battery is Depleted, Presents Rd A Mini-Dock with Charging UFP works! After Host is sufficiently charged, it can establish an Explicit PD Contract for more power, and initiate a DR_Swap C
Mini Dock
C
C
PD
November 17 – 18, 2015
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USB Developer Days 2015
Disaster Scenario Overview PD Adapter is powering Mini-Dock and Host PD Adapter is Disconnected!
Mini Dock
HDMI
C
C USB
C
PD
November 17 – 18, 2015
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USB Developer Days 2015
How Long Can You Survive Without Power?
November 17 – 18, 2015
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USB Developer Days 2015
I Will Survive!
Vconn_Swap! It’s a Lifesaver!
November 17 – 18, 2015
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USB Developer Days 2015
Key Takeaways • Topics Covered: • USB-C Docking vs Traditional USB Docking • Consider USB-C not necessarily as a connector that will replace everything, but rather, it’s the first connector that offers high speed data transfer, native video, and higher power chargers.
• Power Budgeting Basics • Self-Powered vs Bus-Powered • For Legacy-A Ports, Maximum Power Should Be Allocated • A Flexible Power Policy that’s more accepting of Chargers might provide a better user experience • Support Get_Sink_Cap so Chargers can more intelligently distribute power
• Protocol Walkthrough • Consider the Order of Events • Consider Unexpected Disconnect Cases November 17 – 18, 2015
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USB Developer Days 2015
Q&A Session
November 17 – 18, 2015
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USB Developer Days 2015
Backup Materials
November 17 – 18, 2015
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USB Developer Days 2015
Bus-Powered Self-Powered • Assumption: PD-Capable USB-C Port UFP, DC Jack • Conceptual Flow: 1. Device’s UFP is connected to Host’s DFP, Establishes Explicit Contract 2. DC Power Supply is connected to Device’s DC Jack a.
At this point, the Device is Self-Powered
3. Device can send updated Request message to re-negotiate a new Contract to reflect this change eg, Operating Current = 100 mA a.
Consider maintaining a minimal Contract (or utilizing Vconn if available) since the user can still disconnect the DC Supply… C
DC Supply
November 17 – 18, 2015
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USB Developer Days 2015
“Where there is great power there is great responsibility, where there is less power there is less responsibility, and where there is no power there can, I think, be no responsibility.” —Winston Churchill, 1906
November 17 – 18, 2015
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USB Developer Days 2015
VL100 Multiple USB-C™ Applications • USB-IF Certified (Single-Port Mode) • MP Now! Part Number
Description
Package
VL100-Q3
USB-C Alt-Mode Accessory w/ Captive Cable (UFP/Charging UFP, Vconn Power Support)
32-pin QFN (5x5mm)
Video Dongles VL100-Q4
USB-C Charge-Through w/ Captive Cable (Charging UFP, Sinking DFP, Vconn Power Support)
40-pin QFN (5x5mm)
Alt-Mode Accessory w/ Charge-Through USB-C Accessory w/ Charge-Through
VL100R-Q4
USB-C Charge-Through w/ USB-C Receptacle (Charging UFP, Sinking DFP)
40-pin QFN (5x5mm)
Docking Stations
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USB Developer Days 2015
VL100 Block Diagram
Single Chip w/ Dual USB-C™ PD Ports & Billboard
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USB Developer Days 2015
VL100 + VL210 Multi-Function Dongle
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