usb power delivery · 2/20/2019 · usb developer days –october 24 –25, 2017 usb implementers...

USB Developer Days – October 24 – 25, 2017 USB Implementers Forum © 2017

USB Power DeliveryRichard Petrie – Microchip

Bob Dunstan – Renesas(Ed Berrios – ON Semiconductor)

USB Developer Days 2017

Taipei Taiwan

October 24 – 24, 2017

1

Welcoming Slideshow 1.ppsx

Welcoming Slideshow 1.ppsx


Power Delivery Agenda• Introduction • Architectural Overview• Beyond USB-IF

• IEC standardized chargers • Country Codes/Country Info

• USB Type-C Port Controller• Active Cable Support• PD Authentication• PD Firmware Update• PD System Policy Manager and

Bridging• Fast Role Swap

Following the 10am break …

• Programmable Power Supply (PPS)• Protocol• Power Supply

2

Other related sessions:• USB Type-C Active Cables• USB Type-C Authentication/Firmware Update• USB Type-C Battery Charging• Bridging


Introduction

• Our original vision - achieved

• Standards based charging

• Better Cabling

• Authentication

• Firmware Update

• Bridging

• Port Chips

3


Our original Vision…

4

65W 100W

USB Power Delivery

SSD

HDD

USB 2.0

USB 3.0

USB BC 1.2

2.5W 4.5W 7.5W

Extend ease of use, reduce clutter, reduce waste

• Power increased to 100W• Concept of universal charging being extended by IEC 63002


…achieved++!• Standards-based charging

• Better Cabling

• Authentication

• Firmware Update

• Bridging

• Port Chips

5


Standards based charging • IEC 63002:2016

• Defines universal Chargers

• Covers laptops, tablets and PCs

• Get power from any charger to your battery

• Different charging algorithms• Fixed Voltage

• Sink Directed

• USB-IF certifies• Power adapters, Power banks, UPS’es, Higher power USB ports, Hubs, Docks…

• All can be made compliant and interoperable

6


Better Cabling• Discoverable, configurable cables

• Standard Cabling for all types of applications

• Double the USB bandwidth using 2 lanes

• Active cables• Support longer cabling (up to 60 m)

• Provisions for thermal management

7


USB Type-C Authentication• PD authentication mechanism using globally recognized techniques

• Certificates: X509v3

• Digital signing: ECDSA using NIST P256

• Hash: SHA256

• Cable authentication• Ensures that the cable’s identity is valid

• Port-to-Port authentication• E.g. Sink-to-Source or Source-to-Sink

• Ensures that the Source or Sink’s identity is valid

• The Authentication specification is included as part of the USB 3.2 release bundle found at http://www.usb.org/developers/docs/

8

http://www.usb.org/developers/docs/


Firmware Update• Update mechanism over PD

• Similar to USB Device Firmware Update class (DFU)

• No need to support a USB Host/Device in order to update FW

• Enables update of Sources and Sinks as required

• Specification can be found here:http://www.usb.org/developers/powerdelivery/PD_FW_Update_Specification_Rev_1_0_20160915b.pdf

9

http://www.usb.org/developers/powerdelivery/PD_FW_Update_Specification_Rev_1_0_20160915b.pdf


Bridging

• For Hubs and other products with multiple, independent PD ports

• Enables PD status to be read

• Remote authentication and firmware update over USB via PD

• Compatible with UCSI

• USB based request/response converted to/from PD Messages

• USB Type-C Bridge Class specification can be found here:• http://www.usb.org/developers/docs/devclass_docs/USB_Type-C_Bridge_Spec.zip

10

http://www.usb.org/developers/docs/devclass_docs/USB_Type-C_Bridge_Spec.zip


Port Chips

• USB Type-C Port Chip (TCPC)

• Standalone implementation of USB Type-C states and PD Protocol

• TCPC Interface over I2C defined by specification

• Enables standard silicon implementations of the lower layers of the PD stack.

• The TCPC interface specification is included as part of the USB 3.2 release bundle found at http://www.usb.org/developers/docs/

11

TCPC Interface (TCPCI)

http://www.usb.org/developers/docs/


Architectural Overview

• Terminology

• Attach/Detach Detection

• Physical Layer

• PD System Overview

• Messages

• Alternate Modes

12


Terminology• DFP/UFP

• Defines the Port’s position in the USB topology• DFP is equivalent to A-Port/Host, UFP is equivalent to B-Port/Device• Does not imply USB Communication Capability

• Source/Sink• Defines the power role the port is currently operating in

• DRP (Dual-role Power)• Port can operate as either a Source or a Sink

• DRD (Dual-role Data)• Port can operate as either a DFP or a UFP

• USB Communications Capable• Port can send/receive USB traffic – may be asymmetric for DFP/UFP

• SOP*• Start of packet (SOP/SOP’/SOP’’)

13


PD SystemOverview

• Power Source/Sink (Chapter 7)• Controls power transitions

• Device Policy (Chapter 8)• Policy Engine

• Drives the Atomic Message Sequences• Device Policy Manager

• Handles PD across multiple ports• Makes decisions on how to allocate power• Talks to Power Source/Sink and Cable

Detection

• USB-C Port Control• USB Type-C state operation

(attach/detach)

• Physical Layer (Chapter 5)• Port to Port over CC wire• Collision Avoidance

• Protocol Layer (Chapter 6)• Handles retries, message construction

and chunking

14

Power

Source(s)

Physical

Layer

Protocol

Source Port

Device Policy Manager

Source

Policy

Engine

Power

Sink

Physical

Layer

Protocol

Sink Port


Sink

Policy

Engine

USB-C

Control

USB-C

Control

VBUS USB PortVBUSUSB Port CC CC

BMCBMC

CC

VBUS


Attach/Detach Detection• Source (Rp asserted)

• Presence of Rd indicates port to port attach• Immediately sends Source Capabilities

• Waits for GoodCRC and Request or times out and does a Hard Reset

• Absence of Rd indicates detached state

• Sink (Rd asserted)• Presence of Vbus indicates it is attached to a Source

• Responds with GoodCRC to Source Capabilities and then sends a Request

• When VBUS is removed• During PR_Swap connection is retained

• During Hard Reset if self-powered and can operate connection is retained

• At other times this means detached

15


Physical Layer• Signal is DC coupled on USB Type-C CC wire

• 300 kbps half duplex communication system

• Uses Bi-mark phase Coding (BMC)

• CRC-32 used to detect data corruption

• 4b5b K-codes and 4 K-code ordered sets used for markers (SOP, EOP, Hard Reset etc.)

• USB Type-C Current (Rp) used for collision avoidance

16


Protocol

• Defines three types of messages:• Control Messages• Data Messages

(data payload up to 28 bytes)• Extended Data Messages

(up to 256 byte payload)

• Every packet is acknowledged with a response (GoodCRC)

• 3 tries and you are out

• Defines message usage:• Negotiating power contracts• Data/Power/VCONN role swapping• Alerts/status/extended

capabilities/identity• Alternate Mode entry/exit• Authentication• Firmware Update• Other vendor defined messages

17


Device Policy Manager• One instance per device

• Acts across one or more ports

• Manages bus traffic

• Manages power resources in the device

• Monitors and controls the power supply

• Interacts with the cable detection module

• Causes Policy Engine to enact policy for a given port

• Optional USB interface to System Policy

18

Power

Source(s)/

Sink

Physical Layer

Protocol

Source Port


Policy Engine

USB-C Control

System Policy

Manager

PD USB Device

USB Host

USB hub tree

(optional)

USB Interface

(optional)


USB Bridge Class Specification• OSPM includes the System Policy Manager

(SPM) capability

• Provides OS visibility into Power Delivery

• System can overlay a coordinated policy on device policy

• Communication is done over USB

• Devices report capabilities

• Hubs report and allow limited control of their downstream ports

19

OSPM OSAMOSFUM

USB Type-C Bridge Class Driver

Core USB Stack

xHCI

USB-C

PDUSB Host

USB-C

USB Hub logicOR

USB Device Logic

USB Type-C Bridge

USB PD Device Policy Manager (DPM)

PPM PAMPFUM

Device Container

USB PD Logic

PD Protocol Layer

PD PHY

PD Policy Engine

USB-C

PD Protocol Layer

PD PHY

PD Policy Engine

USB-C

PD Protocol Layer

PD PHY

PD Policy Engine

USB-C


Bringing it all together• Negotiating power is simple and robust

• Source sends its capabilities

• Sink makes a Request

• Source Accepts and send PS_Ready

• What happens when the Sink needs more power?• Sink can indicate that it needs more power (Capability Mismatch)

• Source can read Sink’s capabilities to determine what it needs to function

• Extended capabilities used to exchange additional information between Source and Sink

• Status provides real-time operational information

20


Following the spec is important• Simple things can cause big problems

• Reserved bits / values• Spec requirement: Set to 0 by the sender – to be ignored by the receiver

• Rationale was to allows these bits to be used by future revisions without impacting previous revisions

• Problem seen in the field• Revision 3 APDO used for PPS defined a previously reserved value

• Some Revision 3 Sinks did not ignore the reserved value and could not properly understand the new data object and did Hard Resets

• The result is that they would not get any power from a properly operating PPS charger – Bad User Experience!

21


Alternate Modes• Alternate modes reconfigure the connector

• Repurpose pins to support another bus• Change the mode of operation of a bus• Enable sideband signals

• Alternate modes may reconfigure the cable• Change signal conditioning type or direction

• Note: Accessory Mode is not the same

22

Full featured cable – configurable pins Direct attach – configurable pins


Alternate Mode Process• Discover SVIDS

• Device/cable returns the SVIDS for which is has modes

• Discover Mode• Device/cable returns the modes is has for

each SVID

• Host evaluates the intersection of the modes it and the device/cable supports

• USB Safe State• Prevent any signaling that appears on data

wires from damaging USB PHY• May be simple isolation (mux/switch)• May be very robust PHY inputs

• Enter mode – SVID + mode

23

Initiator (DFP) Responder (UFP or Cable Plug)

Discover SVIDs

List of SVIDs

Discover Modes (SVID)

Modes for SVID

For every DFP supported SVID

Modes Supported?

N Stay in USB

mode

Y

Enter Mode

ACK (Responder switched to Mode)

Initiator and Responder operate using Mode

Return to USB mode

Establish PD Contract

Exit Mode or PD Hard Reset or cable unplugged or power

removed?

Y

N

USB Safe State


Failure to find an Alternate Mode• Alternate mode device does not receive an Enter Alternate Mode

command• Host does not support PD so does not look for alternate mode devices

• Host finds alternate mode devices, but does not support this particular device

• Alternate mode device presents either an ‘equivalent USB function’ and/or USB Billboard Device interface to the USB stack

• BB device provides the OS with information about the alternate mode device that it can use to inform the user that the host does not support the alternate mode

• Billboard applies to alternate mode devices and adapters• Does not apply to cables that support alternate modes.

24


E-Marked Cables

25


Multi-drop used to access cable

• Multi-drop• Packet structure unchanged• Start of packet is message ‘address’ (SOP’/SOP’’)• Limited access to the new ‘addresses’• Electronically marked cables respond to SOP’

• Only the VCONN Source can reliably talk to the cable

• Source of VCONN controlled via with VCONN_Swap

• Single initiator of multi-drop message sequences

• Cable Plug not allowed to initiate messages• Source allowed to initiate communication

SOP’ prior to an explicit contract• DFP can initiate communication SOP’/SOP’’

within an explicit contract

26

DFP UFP

SOP signaling

SOP’signaling

SOP’’signaling

Cable Plug

(SOP’’)Electronically Marked Cable

Cable Plug

(SOP’)VCONN


Electronically Marked Cable

Discover Identity used to get cable information

• HW/FW Version

• VDO Version

• Cable Connectors

• Cable Latency

• VCONN required

• VBUS

• Current capability

• Voltage

27

SOP’

VBUS

GND

VCONN

(Not sourced)

CC

VBUS

GND

VCONN

(Sourced)

CC

DFP UFPElectronically Marked Cable

Ra Ra

Iso( )

Iso( )

• USB Support• USB 2 only

• SuperSpeed Gen 1

• SuperSpeed Gen 2


Active Cables• PD Support for Active Cables

• Active Cable VDO

• Active Cable Thermal Management

28


PD Support for Active Cables• Active Cable info updated

• Get Status extended to SOP’ and SOP’’ to return • Operating temperature

• Thermal shutdown flag

29


Active Cable VDO • HW/FW Version

• VDO Version (1.1)

• USB Type-C cable / Captive cable

• Latency (proxy for length)

• VBUS

• Supported• Voltage• Current carrying capability

• SBU• Supported• Passive/Active

• SOP’’ controller

• Operating temperature

• Shutdown temperature

• USB Support • USB 2.0• USB 3.2• Lanes (one/two)• Gen1/Gen2

30


Active Cable Thermal Management• Half of a plug’s thermal contribution is the result of current

• Sources and/or Sinks may manage the Active Cable’s thermal

• Source• PD Policy Manager

• Periodically reads plugs’ Status (SOP’/SOP’’)

• Compares Operating Temperature to Maximum Operating Temperature from Cable VDO

• As Operating Temperature approaches Maximum Operating Temperature, Source sends out capabilities with reduced current – Sink is required by PD to respond and reduce the current it consumes

• Sink• PD policy manager may do similar by adjusting amount of current Sink

consumes to manage plug temperature

31


Fast Role Swap• Laptop behavior

• Charge-through hub behavior

32


Fast Role Swap• Initial Source (Hub) has power

removed• Maintains power to downstream

peripherals • Stops sourcing power upstream• Needs new power source urgently!• Signals Fast Swap on CC line

• Initial Sink (Laptop) has 5 V Source ready to be applied quickly• Detects Fast Swap• Waits for supply to drop to 5 V• Starts Sourcing 5 V

• In parallel Port Partners start the role swap process• Ensures that Source and Sink roles are aligned

33

Hub

HDD


Fast Role Swap - Laptop• Laptop reads Sink Fixed Supply PDO to see if Fast Role Swap is

supported

• Evaluates the amount of current the Sink requires to support FRS

• If can support the Sink’s requirements, it keeps its 5 V supply up and arms its FRS detection circuit

34


Fast Role Swap - Hub• FRS capable pass-through hub detects removal of power

• Speculatively signals FRS by pulling CC to ground for 60 – 120 µs

• Unpowered, the Hub continues to source VBUS on its downstream ports for at least 150 µs after VBUS falls below vSafe5V

• If Laptop provides VBUS

• Hub uses it to continue powering its downstream ports• Laptop sends FR_Swap message to resynch PD

• If Laptop does not support FRS or Hub fails to Source VBUS on its downstream ports, devices will be dropped and normal USB mechanisms will be used to recover them when VBUS is reapplied

35

Fast Role Swap is a best effort mechanism


Power Delivery Agenda• Introduction • Architectural Overview• Beyond USB-IF

• IEC standardized chargers • Country Codes/Country Info

• USB Type-C Port Controller• Active Cable Support• PD Authentication• PD Firmware Update• PD System Policy Manager and

Bridging• Fast Role Swap

Following the 10am break …

• Programmable Power Supply (PPS)• Protocol• Power Supply

36


Power Supply

• Power Architecture Overview

• Fixed Source Review

• Programmable Power Source Review

• PPS Example

• Fast Role Swap

• Robust Port Considerations

37


Example Source & Sink Configurations

38

Source

VBUSVBUSVBUSVBUS

Legacy

Power

Source

System Power

External Power

BatteryPD

Source Port

Dual-Role Power

VBUSVBUSVBUSVBUS

Legacy

Power

Source

System Power

External Power

BatteryDual-Role

Power Port

* must be self powered

Sources

Sinks

Sink

VBUS

PD

Sink Port

System Power

External Power

Battery

Dual-Role Power

VBUS

System Power

External Power

BatteryDual-Role

Power Port

* must be self powered


Source Positive Transitions

39

• The voltage limits to do not apply to vSafe0V and vSafe5V

Starting voltage

vSrcNew(typ)

t0

vSrcSlewPos

tSrcSettle

vSrcValid(max)

vSrcValid(min)

Upper bound of valid Source range

vSrcNew(max)

vSrcNew(min)

tSrcReady

Lower bound of valid Source range

≈

≈

+0.5 V

105 %

95 %

−0.5 V

275 msec 285 msec

30 mV/usec


Sink Load I1

vSrcNew(typ)

tSrcReady

iLoadStepRate

vSrcValid(max)

vSrcValid(min)

vSrcNew(max)

vSrcNew(min)tSrcTransient window

≈

tSrcTransient windows

≈

≈

iLoadReleaseRate

Sink Load I2

Application of vSrcNew & vSrcValid after tSrcReady

40

+0.5 V

105 %

95 %

−0.5 V

285 msec

5 msec

5 msec

150 mA/usec−150 mA/usec


Transition to Increase Voltage

41

t3t1

t2Source VOLD Source VNEW

Send

Accept

Evaluate

Accept

Send

PS_RDY

Evaluate

PS_RDY

Sink ≤ IOLDSink ≤ IOLD

≤ IOLD ≤ IOLD

I1

Sink to Sink

Standby

Sink pSnkStdby

Sink Standby

to Sink

VOLD

Source

ñ V

4

1

2

3

5

6

7

Source Port

Policy Engine

Sink Port

Policy Engine

Source Port

Device Policy Mgr

Source Port

Power Supply

Sink Port

Device Policy Mgr

Sink Port

Power Supply

Source Port

Voltage

Sink Port

Current

I1 ≤ (pSnkStdby/VBUS) I2 ≤ (pSnkStdby/VBUS) + cSnkBulkPd(DVBUS/Dt)

I2

VNEW

I1

...

8

≈

PSTransitionTimer (running)

tSrcTransition

Port to Port

Messaging

Source Port

Interaction

Sink Port

Interaction

Source

VBUS Voltage

Sink

VBUS Current


Transition to Increase Current

42

Source Port

Policy Engine

Send

Accept

Sink Port

Policy Engine

Evaluate

Accept

Source Port

Device Policy Mgr

Source Port

Power Supply

Sink Port

Device Policy Mgr

Sink Port

Power Supply

Send

PS_RDY

Evaluate

PS_RDY

Sink ≤ INEWt2

Source Port

Voltage

Sink Port

Current

Sink ≤ IOLD

≤ IOLD

≤ INEW

Sink

ñ I

VBUS doesn’t change

Source

ñ I

3

1

2

4

5

6

PSTransitionTimer (running)

...

7

≈

Source VOLD Source VOLD

tSrcTransition

t1

Port to Port

Messaging

Source Port

Interaction

Sink Port

Interaction

Source

VBUS Voltage

Sink

VBUS Current


PPS Capabilities• New PDO Type Augmented PDO (APDO)

• Source Capability• Min/Max Voltage

• Max Current

• New RDO• Voltage between min/max

• Current Limit

• PPS Status• Operating Mode (CV/CL)

• Source voltage/current

43


PPS Operation• Safety first!

• Over Current/Over Temperature protection required

• Periodic communications with Sink required

• Alerts for OC/OT events

• Sink Directed Charging• Sink periodically (at least every 10 seconds) requests Voltage/Current

• Source operates in constant voltage mode or current limit mode depending the on load

• Source provides status (operational mode, voltage and current)

• Source returns to its safe state when communications with the Sink are lost

44


What is Programmable Power Supply (PPS)• Defines a method to adjust the Source output voltage in 20 mV steps

• Defines a method to adjust the Source current limit in 50 mA steps

• Current limit operation only occurs when the Sink attempts to draw more than the negotiated current level

• Current limit mode is for normal operation, not for protection

• Standard PPS voltage ranges are defined in Chapter 10

• Sinks do not transition to Sink Standby during PPS voltage changes

45


Fixed Sources & Programmable Power Sources

46

Aspect Fixed Source Programmable Power Source

Constant Voltage mode(refer to Chapter 10)

5 V9 V15 V20 V

3.0 V to 5.9 V3.0 V to 11.0 V3.0 V to 16.0 V3.0 V to 21.0 V

Step Size None Nominal 20 mV

Current Limit mode None Yes, nominal 50 mA steps

Sink transition to pSnkStdby Yes – between all voltage changes No, not when operating with PPS

Periodic RDOs during operation No – does not apply Yes, needed for PPS operation

Requires Robust Port Design Yes Yes


PPS = Programmable Voltage + Current Limit

• Shaded areas indicate the highest or lowest nominal output voltage or operating current PPS APDO including tolerance

• PPS APDO Min Voltage is the same value across all of the APDOs

• The sloped line during Constant Voltage mode indicates the load regulation characteristic of power converters

47

Current

Volta

ge

PPS APDO

Min Voltage

PPS APDO

Max Voltage

iPpsCLMinPPS APDO

Max Current

vPpsNew

PPS RDO

Operating Current

PPS RDO

Output Voltage

Programmable

Voltage Only

Region

Programmable Voltage &

Programmable Current Limit Region

Valid Current Limit Response

Invalid Current Limit Response

iPpsCLNew

a

Operating Mode Flag set

Operating Mode Flag cleared

iPpsCLOperating

b

c

d


Coming to Terms with PPS• X-axis

• iPpsCLMin = Parameter defined in Table 7-19 as 1 A

• PPS RDO Operating Current = Requested current level Section 6.4.2

• PPS APDO Max Current = Maximum current based on PDP Section 10.2.2

• Y-axis• PPS APDO Min Voltage = Min voltage which is 3.0 V regardless of PDP

• PPS RDO Output Voltage = Requested voltage level Section 6.4.2

• PPS APDO Max Voltage = Max voltage which is defined by PDP

48


Current

Vo

ltag

e

PPS APDOMin Voltage3.0 V

PPS APDOMax Voltage11.0 V

iPpsCLMin1.0 A

PPS APDO Max Current

3 A

PPS RDOOperating Current

50 mA steps

PPS RDOOutput Voltage20 mV steps

Programmable Voltage Only

Region

Programmable Voltage & Programmable Current Limit Region

Axis for PDP = Prog9V, PDP = 27 W• PPS RDO Output Voltage

step size is fixed at 20 mV nominal

• PPS RDO Operating Current step size is fixed at 50 mA nominal

• Min and max PPS range are defined by the PPS APDO

• Output voltage and operating current of the PPS is defined by the PPS RDO

• Current limiting is not defined for PPS APDOs or PPS RDOs below 1 A

49


Current

Vo

ltag

e

PPS APDO

Min Voltage

PPS APDO

Max Voltage

iPpsCLMinPPS APDO

Max Current

vPpsNew

PPS RDO

Operating Current

PPS RDO

Output Voltage

20 mV steps

Programmable

Voltage Only

Region



a



b

Constant Voltage Segment of the PPS Curve

• The PPS RDO output voltage step size is fixed at 20 mV nominal

• The PPS RDO output voltage can be changed in single-bit or multiple-bit steps

• PPS output voltage regulation occurs to the left of the point designated as (a)

• The vPpsNew tolerance is ± 5%

50


Constant Voltage – Voltage Parameters

51

vPpsCLCvTransient Operating Voltage

x 0.95 – 0.1VOperating Voltage

x 1.05 + 0.1VV

This limit only applies when a load change causes a transition from current limit mode to constant voltage mode.

vPpsCvCLTransientOperating Voltage

– 1.0VOperating Voltage

+ 0.5VV

This limit only applies when a load changes causes a transition from constant voltage mode to current limit mode.

vPpsMaxVoltageAPDO Voltage

x 0.95APDO Voltage

x 1.05V ± 5% constant voltage tolerance for all PPS voltages.

vPpsMinVoltageAPDO Voltage

x 0.95APDO Voltage

x 1.05V ± 5% constant voltage tolerance for all PPS voltages.

vPpsNewRDO Output

Voltage x 0.95RDO Output

VoltageRDO Output

Voltage x 1.05V ± 5% constant voltage tolerance for all PPS voltages.

vPpsSlewNeg −30 mV/µsThis is the same slew rate limit as the fixed supply requirements.

vPpsSlewPos 30 mV/µsThis is the same slew rate limit as the fixed supply requirements.

vPpsStep 20 mVNominal output voltage change for every LSB change of PPS RDO Output Voltage.

vPpsValid −0.1 0.1 VAdditional allowance beyond ± 5% for load step transient response. Only applies to when the PPS is in constant voltage mode before and after the load step.


Constant Voltage Tolerance, Step Size & Monotonicity

• The regulation tolerance is ± 5%

• The Constant Voltage RDO steps size is 20 mV nominal

Example:

• RDO Output voltage = 4.0 V, the valid regulated range is 3.8 V to 4.2 V

• +1 LSB change of RDO increases the output voltage by 20 mV nominal• A non-positive change of the output voltage in response to +1 LSB change of

RDO violates the monotonicity requirement

52


Current

Vo

ltag

e

PPS APDO

Min Voltage

PPS APDO

Max Voltage

iPpsCLMinPPS APDO

Max Current

PPS RDO

Operating Current

PPS RDO

Output Voltage

Programmable

Voltage Only

Region



a



iPpsCLOperating

b

Current Limit Segment of the PPS Curve

• PPS shall exhibit a current limit response like the one shown in the diagram

• The opposite slope is not allowed

• PPS is not required to provide power for voltages below the PPS APDO Min Voltage, including tolerance

• PPS output current limiting shall occur below the point designated as (b)

53


PPS Current Limit – Current Parameters

54

iPpsCLMin 1 ACurrent Limit mode is only required when the PPS RDO Operating current is above 1 A.

iPpsCLNew−150 +150 mA

Current Limit mode accuracy when the PPS RDO Operating Current is 1 A or greater and 3 A or less.

−5 +5 %Current Limit mode accuracy when the PPS RDO Operating Current is greater than 3 A.

iPpsCLOperating 0 +100 mARange beyond iPpsCLNew over which the current can vary during Current Limit mode.

iPpsCLStep 50 mANominal output current change for every LSB change of PPS RDO Operating Current.

iPpsCLTransient −250 +250 mARange over which the current can vary during a load transient which does not cause a transition out of Current Limit mode.

iPpsCvCLTransient −100 +500 mARange over which the current can vary during a load transient which causes a transition from Constant Voltage mode to Current Limit mode.


Current

Vo

ltag

e

PPS APDO

Min Voltage

PPS APDO

Max Voltage

iPpsCLMinPPS APDO

Max Current

PPS RDO

Operating Current

PPS RDO

Output Voltage

Programmable

Voltage Only

Region





a



iPpsCLOperating

b

Good versus Bad PPS Current Limit Response

• A current limit response that goes outside of the iPpsCLOperating band is not allowed

• A current limit slope where voltage decreases with decreased load current is not allowed

• Current limit responses do not need to span the entire iPpsCLOperating band from left to right

55


Current

Vo

ltag

e

PPS APDO

Min Voltage

PPS APDO

Max Voltage

iPpsCLMinPPS APDO

Max Current

PPS RDO

Operating Current

PPS RDO

Output Voltage

Programmable

Voltage Only

Region



iPpsCLNew

a



b

Constant Voltage to Current Limit and Back• Left of point (a) the PPS output

current is below the tolerance band for a given PPS RDO Operating Current therefore is in Constant Voltage mode

• Operating Mode Flag is cleared

• Below point (b) the PPS output voltage is below the tolerance band for a given PPS RDO Output Voltage therefore is in Current Limit mode

• Operating Mode Flag is set

• The state of the Operating Mode Flag between points (a) and (b) is not defined and the operational mode is unknown

56


Sink

PPS Adapter

VBUSCC

PPS Charging Example

• Conceptually the Sink controls the PPS to charge its battery

• The Sink sends periodic RDOs to keep-alive the Source ‘you must’

• In practice, the Sink must provide local regulation and battery protection

57

Sink

PPS Adapter

Local voltage & current regulation

Battery Monitoring & Safety

VBUSCC


Safe Charge

58

Current

Vo

ltag

e

PPS APDOMin Voltage

PPS APDOMax Voltage

iPpsCLMinPPS APDO Max Current


PPS RDOOutput Voltage


Region


a



b

Bat

tery

Cu

rren

t &

Bat

tery

Vo

ltag

e

(IBAT)

(VBAT)

safe pre constant current constant voltage eoc

PPS RDO Output Voltage

LOW battery current & LOW battery voltagePPS in Constant Voltage modeOperating Mode Flag is cleared

PPS RDO 1

PPS RDO 2


Current

Vo

ltag

e

PPS APDOMin Voltage

PPS APDOMax Voltage





Region


a



b

Pre Charge

59

LOW charging current & LOW battery voltagePPS in Constant Voltage modeOperating Mode Flag is cleared

PPS RDO 1

PPS RDO 2

Bat

tery

Cu

rren

t &

Bat

tery

Vo

ltag

e

(IBAT)

(VBAT)




Current

Vo

ltag

e

PPS APDO

Min Voltage

PPS APDO

Max Voltage

iPpsCLMinPPS APDO

Max Current

PPS RDO

Operating Current

PPS RDO

Output Voltage

Programmable

Voltage Only

Region



a



b

Start of CC Charge

60

HIGH charging current & LOW battery voltagePPS in Current Limit modeOperating Mode Flag is set

PPS RDO 1

PPS RDO 2

Bat

tery

Cu

rren

t &

Bat

tery

Vo

ltag

e

(IBAT)

(VBAT)




Progressing through CC Charge

61

HIGH charging current & INCREASING battery voltagePPS in Current Limit modeOperating Mode Flag is set

PPS RDO 1

PPS RDO 2

Bat

tery

Cu

rren

t &

Bat

tery

Vo

ltag

e

(IBAT)

(VBAT)



Current

Vo

ltag

e

PPS APDO

Min Voltage

PPS APDO

Max Voltage

iPpsCLMinPPS APDO

Max Current

PPS RDO

Operating Current

PPS RDO

Output Voltage

Programmable

Voltage Only

Region



a



b


Nearing the End of CC Charge

62

HIGH charging current & HIGH battery voltagePPS in Current Limit modeOperating Mode Flag is set

PPS RDO 1

PPS RDO 2

Bat

tery

Cu

rren

t &

Bat

tery

Vo

ltag

e

(IBAT)

(VBAT)



Current

Vo

ltag

e

PPS APDO

Min Voltage

PPS APDO

Max Voltage

iPpsCLMinPPS APDO

Max Current

PPS RDO

Operating Current

PPS RDO

Output Voltage

Programmable

Voltage Only

Region



a



b


Current

Vo

ltag

e

PPS APDO

Min Voltage

PPS APDO

Max Voltage

iPpsCLMinPPS APDO

Max Current

PPS RDO

Operating Current

PPS RDO

Output Voltage

Programmable

Voltage Only

Region



a



b

Start of CV Charge

63

HIGH charging current & HIGH battery voltagePPS in Constant Voltage modeOperating Mode Flag is cleared

PPS RDO 1

PPS RDO 2

Bat

tery

Cu

rren

t &

Bat

tery

Vo

ltag

e

(IBAT)

(VBAT)




Current

Vo

ltag

e

PPS APDO

Min Voltage

PPS APDO

Max Voltage

iPpsCLMinPPS APDO

Max Current

PPS RDO

Operating Current

PPS RDO

Output Voltage

Programmable

Voltage Only

Region



a



b

Progressing through CV Charge

64

DECREASING charging current & HIGH battery voltagePPS in Constant Voltage modeOperating Mode Flag is cleared

PPS RDO 1

PPS RDO 2

Bat

tery

Cu

rren

t &

Bat

tery

Vo

ltag

e

(IBAT)

(VBAT)




Current

Vo

ltag

e

PPS APDO

Min Voltage

PPS APDO

Max Voltage

iPpsCLMinPPS APDO

Max Current

PPS RDO

Operating Current

PPS RDO

Output Voltage

Programmable

Voltage Only

Region



a



b

Nearing the End of CV Charge

65

LOW charging current & HIGH battery voltagePPS in Constant Voltage modeOperating Mode Flag is cleared

PPS RDO 1

PPS RDO 2

Bat

tery

Cu

rren

t &

Bat

tery

Vo

ltag

e

(IBAT)

(VBAT)




Example PPS Responses

66

Bat

tery

Cu

rren

t &

Bat

tery

Vo

ltag

e

(IBAT)

(VBAT)



Bat

tery

Cu

rren

t &

Bat

tery

Vo

ltag

e

(IBAT)

(VBAT)



Bat

tery

Cu

rren

t &

Bat

tery

Vo

ltag

e

(IBAT)

(VBAT)


Bat

tery

Cu

rren

t &

Bat

tery

Vo

ltag

e

(IBAT)

(VBAT)



“The Presenter” “The Cooler”

“The Nudge” “The Optimizer”

2 PPS RDOs&

Periodic RDOs

3 PPS RDOs&

Periodic RDOs

4 PPS RDOs&

Periodic RDOs

10 PPS RDOs&

Periodic RDOs


PPS – What can go wrong?• Output voltage did not increment/decrement from previous value

• Output is supposed to be monotonic with 20 mV steps

• Output voltage transition times not met on large voltage changes• Upcoming ECN will relax requirement for large transitions

• Current Limit mode not supported• Required for PPS

• Minimum voltage• 3 V requirement not met• Discussions to raise the minimum voltage are underway

• PPS Status• OMF flag not properly set• Voltage/Current not reported correctly

• Response to Hard Reset• Vbus discharge to vSafe0V• Active discharge or allow to decay – inconsistent behavior

67


Fast Role Swap (FRS)

1. The Notebook discovers if the Charge-thru Hub supports FRS

2. The Notebook arms itself

3. The Charge-thru Hub signals FRS to Notebook on Port 3 when the Adapter is removed

4. (a) The Notebook supplies VBUS through Port 3 when VBUSvoltage reaches vSafe5V

(b) The Port 2 VBUS is held at vSafe5V

5. PD unravels the mess !

68

NotebookAdapter

Charge-thru Hub

Port 3

USB Device

Port 1

Port 2 Hold Cap


NotebookAdapter

Charge-thru Hub

Port 3

USB Device

Port 1

Port 2 Hold Cap

Power Flow during Fast Role Swap (FRS)

• Green arrows indicate progression of FRS

• Black arrows indicate direction of power flow

• FRS Objective is to keep the USB Device powered

69

Source Sink

Sink

Notebook

Charge-thru Hub

Port 3

USB Device

Port 1

Port 2 Hold Cap

Source

Sink

Notebook

Charge-thru Hub

Port 3

USB Device

Port 1

Port 2 Hold Cap

Source

Sink

Adapter Powered

Hold Capacitor Powered

Host Powered


ECRs being discussed

• Increase of PPS APDO Min Voltage• Presently published at 3.0 V

• May be increased to 3.3 V

• Clarify definition of PS_RDY for PPS• 25 ms for PPS APDO voltage changes < 0.5 V

• Longer for PPS APDO voltage changes ≥ 0.5 V

70

Current

Vo

ltag

e

PPS APDOMin Voltage

PPS APDOMax Voltage


vPpsNew




Region




iPpsCLNew

a

Current Limit Flag set

Current Limit Flag cleared

iPpsCLOperating

b

c

d


Port Robustness Philosophy

• Sources protect themselves

• Sources shall not rely on Sinks for protection

• Sinks protect themselves

• Sinks shall not rely on Sources for protection

71

Robust Source and Sink design does not equateto regulatory safety compliance


Robust Source Port Considerations

• Output Over Current Protection

• Over Temperature Protection

• vSafe5V to vSafe5V Connection

• VBUS Discharge at Detach

• PPS Expects Periodic RDOs from Sink

Note: Sources are required to protect themselves from damage. Source protection mechanisms are not expected to protect Sinks.

72


Robust Sink Port Considerations

• Input Over Voltage Protection

• Over Temperature Protection

• VBUS Discharge at Detach

• Sends Periodic RDOs to PPS

Note: Sinks are required to protect themselves from damage. Sink protection mechanisms are not expected to protect Sources.

73


Q&A

74

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