Jerome Tija

8/12/2019 Jerome Tija

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USB On-The-Go

Electrical

USB On-The-Go

ElectricalJeromeJerome TjiaTjia

Philips SemiconductorsPhilips Semiconductors


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AgendaAgenda!! VVBUSBUS input and output specinput and output spec

!! VVBUSBUS threshold voltages and usagethreshold voltages and usage

!! SRP ElectricalSRP Electrical

!! Data Line Resistance TolerancesData Line Resistance Tolerances

!! OTG TransceiverOTG Transceiver

!! Other ConsiderationsOther Considerations


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Major VBUSChangesMajor VBUSChanges!! AA--device supplies > 8device supplies > 8 mAmA (@ 4.4(@ 4.4 5.25 V)5.25 V)

Accurate Accurate overcurrentovercurrent detection detection

!! OTG peripheralOTG peripheral--only draws < 8only draws < 8 mAmA beforebeforebeing configuredbeing configured


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VBUS Output CharacteristicsVBUS Output Characteristics!! Provides 4.4Provides 4.4--5.25V @ > 85.25V @ > 8 mAmA

4.754.75--5.25V if > 1005.25V if > 100 mAmA

!! LowLow--voltage detection (overvoltage detection (over--current) at 4.4Vcurrent) at 4.4V

!!Rise time < 100 msRise time < 100 ms!! When not driven:When not driven:

Impedance 40kImpedance 40k--100k ohm100k ohm

and leakage < 0.2 Vand leakage < 0.2 V

!! Decoupling 1.0Decoupling 1.0--6.56.5 uFuF

vsvs

standard host > 96standard host > 96

uFuF

VBUS

Valid

VBUS

+40k-100k !

4.4-5.25V

>8mA

>4.4V

1-6.5 uF

4.4V

0V


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VBUS Input RestrictionsVBUS Input Restrictions!! OTG DualOTG Dual--rolerole unconfiguredunconfigured current < 150current < 150 uAuA

!! OTG PeripheralOTG Peripheral--onlyonly unconfiguredunconfigured current < 8current < 8 mAmA

!! Configured current not defined in the supplementConfigured current not defined in the supplement

Possibility of supporting more than 8Possibility of supporting more than 8 mAmA

!! Peak/transient current:Peak/transient current:

Cause < 400 mV VBUS droopCause < 400 mV VBUS droop Current edge rate < 100Current edge rate < 100 mAmA/us/us

Average current (over 1 ms) < 8Average current (over 1 ms) < 8 mAmA


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!! Data Line Resistance TolerancesData Line Resistance Tolerances

!! OTG TransceiverOTG Transceiver



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VBUSThreshold VoltagesVBUSThreshold Voltages!! Spec defines 4 VSpec defines 4 VBUSBUS threshold voltagesthreshold voltages

VVA_VBUS_VLDA_VBUS_VLD (A VBUS Valid)(A VBUS Valid)

VVA_SESS_VLDA_SESS_VLD (A Session Valid)(A Session Valid)

VVB_SESS_VLDB_SESS_VLD (B Session Valid)(B Session Valid)

VVB_SESS_ENDB_SESS_END (B Session End)(B Session End)


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A-Device VBUSThresholdsA-Device VBUSThresholds!! AA--device Vdevice VBUSBUS thresholds:thresholds:

VVA_VBUS_VLDA_VBUS_VLD"" SessionSession--inin--progress (as detected by Aprogress (as detected by A--device)device)

"" Acts as overActs as over--current conditioncurrent condition

VVA_SESS_VLDA_SESS_VLD"" VVBUSBUS pulsing SRP detectionpulsing SRP detection

"" Session end for ASession end for A--devicedevice## Returns to idle stateReturns to idle state


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B-Device VBUSThresholdsB-Device VBUSThresholds!! BB--device Vdevice VBUSBUS thresholds:thresholds:

VVB_SESS_VLDB_SESS_VLD"" Session in progress (as detected by BSession in progress (as detected by B--device)device)

VVB_SESS_ENDB_SESS_END"" Session endSession end

"" (V(VBUSBUS has dropped low enough to start another SRP)has dropped low enough to start another SRP)

"" Active lowActive low


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VBUS Threshold ValuesVBUS Threshold Values!! The 4 threshold valuesThe 4 threshold values

VVA_VBUS_VLDA_VBUS_VLD (A V(A VBUSBUS Valid)Valid)

> 4.4V> 4.4V

VVB_SESS_VLDB_SESS_VLD (B Session(B Session

Valid) 0.8Valid) 0.8--4.0V4.0V

VVA_SESS_VLDA_SESS_VLD (A Session(A Session

Valid) 0.8Valid) 0.8--2.0V2.0V

VVB_SESS_ENDB_SESS_END (B Session End)(B Session End)

0.20.2--0.8V0.8V

"" May be inferred throughMay be inferred through

timingtiming

4V

4.4V

2V

0.8V

0.2V0V

5.25V

B Session End

A Session Valid

B Session Valid

A Vbus Valid


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!! Data Line Resistance TolerancesData Line Resistance Tolerances!! OTG TransceiverOTG Transceiver



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Session Request ProtocolSession Request Protocol!! To save power, ATo save power, A--device may turn off Vdevice may turn off VBUSBUS whenwhen

not in usenot in use!! SRP by BSRP by B--device to start a sessiondevice to start a session

Can also be initiated by OTG peripheralCan also be initiated by OTG peripheral--only deviceonly device

!! BB--device initiates both protocols:device initiates both protocols:

Data Line Pulsing; thenData Line Pulsing; then

VVBUSBUS PulsingPulsing

!! AA--device detects either Data Line or Vdevice detects either Data Line or VBUSBUSPulsing protocolsPulsing protocols

Look for both D+ and DLook for both D+ and D-- if detecting data line pulsingif detecting data line pulsing


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Initial ConditionsInitial Conditions!! BB--device initial conditions before SRP:device initial conditions before SRP:

VVBUS 2 msat SE0 for > 2 ms

"" Ensures that AEnsures that A--device has detected a disconnect and isdevice has detected a disconnect and isable to detect a low to high D+ transitionable to detect a low to high D+ transition


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Data Line Pulsing ElectricalData Line Pulsing Electrical!! Use existing data line pullUse existing data line pull--up circuitup circuit

Including alternative pullIncluding alternative pull--up meansup means

!! Pulse for 5 to 10 msPulse for 5 to 10 ms

!! Pulse DPulse D-- for LS, D+ for FS/HS/DRDfor LS, D+ for FS/HS/DRD

D+ or D-

+

1.5k!" $%

3.0-3.6V

Timer

5-10 ms

>2.7V

0V

5-10ms

Or alternative

termination

means

>2ms


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VBUSPulsing ElectricalVBUSPulsing Electrical!! Charge up ACharge up A--device Vdevice VBUSBUS to > 2.1Vto > 2.1V

Charge up standard host VCharge up standard host VBUSBUS to < 2.0Vto < 2.0V"" (higher decoupling cap)(higher decoupling cap)

!!Charging time not specified but can be derivedCharging time not specified but can be derived ~22 ms~22 ms

"" Standard disclaimer applies hereStandard disclaimer applies here

!! Ensure VEnsure VBUSBUS < 0.8V (session end) before pulsing< 0.8V (session end) before pulsing

!! Current limited to 8Current limited to 8 mAmA in charge/discharge casesin charge/discharge cases


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VBUSPulsing (cont)VBUSPulsing (cont)!! Recommended implementationRecommended implementation

Discharge with > 656 ohm for 656 ohm for 3.0Vvoltage source > 3.0V"" output impedance > 281 ohmoutput impedance > 281 ohm

"" For ~22 ms (disclaimed)For ~22 ms (disclaimed)

VBUS

+

>281!

>3.0V

Timer >656!

2.1V

0V


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Response TimeResponse Time!! How does BHow does B--device know if the SRP isdevice know if the SRP is

successful?successful? After VAfter VBUSBUS pulsing, it should wait for some timepulsing, it should wait for some time

If AIf A

--device does not respond, Vdevice does not respond, V

BUSBUS will decay backwill decay back

to groundto ground

If AIf A--device responds, Vdevice responds, VBUSBUS will be driven by Awill be driven by A--devicedevice

"" And a bus reset is generatedAnd a bus reset is generated Decision time: 5 seconds before informing userDecision time: 5 seconds before informing user

of SRP failureof SRP failure


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Data Line Resistance

Tolerances

Data Line Resistance

Tolerances!! Wider toleranceWider tolerance

Allows resistor on silicon without laser trimmingAllows resistor on silicon without laser trimming

!! PullPull--down resistordown resistor

14.25 to 24.8 k ohm (~ 27% tolerance)14.25 to 24.8 k ohm (~ 27% tolerance)"" (was 15 k ohm +/(was 15 k ohm +/-- 5%)5%)

!! PullPull--up resistorup resistor

Switched resistors (~ 27% tolerance)Switched resistors (~ 27% tolerance)

"" (was 1.5 k ohm +/(was 1.5 k ohm +/-- 5%)5%)

Covered by separate ECNCovered by separate ECN


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Pull-up Resistor ECNPull-up Resistor ECN!! Straight tolerance increase has issuesStraight tolerance increase has issues

Original 1.5 k ohm +/Original 1.5 k ohm +/-- 5%5%

Extend tolerance to lower value affect signal qualityExtend tolerance to lower value affect signal quality"" Jitter, rise/fall time matching, crossJitter, rise/fall time matching, cross--over voltage,over voltage,

eye diagrameye diagram Extend tolerance to higher value lower idle voltageExtend tolerance to higher value lower idle voltage

"" May increase power consumption of transceiversMay increase power consumption of transceivers

!! Switched resistorsSwitched resistors Extend tolerance to lower value during idleExtend tolerance to lower value during idle

Extend tolerance to higher value during activityExtend tolerance to higher value during activity(transmit, receive)(transmit, receive)


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Switched ResistorsSwitched Resistors!! Resistor values:Resistor values:

During idle: 900 to 1575 ohm (around 27% tolerance)During idle: 900 to 1575 ohm (around 27% tolerance)

During activity: 1425 to 3090 ohmDuring activity: 1425 to 3090 ohm

D+ or D- RPU1

PPU2

RPU1 = 900 to 1.575 kRPU2 = 525 to 1.515 k

SW1

SW2

Bus State SW1 SW2Idle Closed Closed

Receiving Closed OpenTransmitting X XVbus Off Open X


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Alternative TerminationAlternative Termination!! Not clearly specified in USB 1.1/2.0 specNot clearly specified in USB 1.1/2.0 spec

!! ECN clarifies/constraints:ECN clarifies/constraints:

PullPull--up voltage up to Vup voltage up to VBUSBUS

Meet idle voltage 2.7Meet idle voltage 2.7--3.6V when terminated with3.6V when terminated withoriginal 15 k ohm +/original 15 k ohm +/-- 5%5%

PullPull--up resistor can be derived:up resistor can be derived:

"" 7.2 k to 8.7 k ohm7.2 k to 8.7 k ohm## Standard disclaimerStandard disclaimer


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VIHZ(Idle Voltage)VIHZ(Idle Voltage)

14.25k-15.75k

1.5k+/-5%

VTERM

=3.3+/-0.3V

VIHZ

=2.7-3.3V (derived)

VIHZ

=2.7-3.6V (spec)

7.2k-8.7k *

VBUS

=4.35-5.25V

VIHZ

=2.7-3.6V (spec)

14.25k-24.8k(ECN)

7.2k-8.7k *

VBUS

=4.35-5.25V

VIHZ

=2.7-4.1V

Original

Termination

Alternative

Termination

Alternative Termination

with ECN resistor

14.25k-15.75k

*derived(disclaimed)


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Pull-Down ECN ImplicationPull-Down ECN Implication!! Higher pullHigher pull--down resistance:down resistance:

Increase in idle voltage levelIncrease in idle voltage level"" Up to 4.1V with alternate termination meansUp to 4.1V with alternate termination means

!!Transceiver design:Transceiver design: To withstand 4.1VTo withstand 4.1V

No backNo back--charging through ESD/parasitic diodecharging through ESD/parasitic diode


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OTG TransceiverOTG Transceiver!! Not part of the supplementNot part of the supplement

!! Integrates OTG analog requirements:Integrates OTG analog requirements:

FS/LS transceiver (HS possible too)FS/LS transceiver (HS possible too) Integrated pullIntegrated pull--up/down resistors and switchesup/down resistors and switches

Charge pump regulator to generate VCharge pump regulator to generate VBUSBUS 5V voltage5V voltage

VVBUSBUS pulsing and discharge SRP circuitpulsing and discharge SRP circuit

VVBUSBUS threshold comparatorsthreshold comparators

Serial Interface (minimize pin connection)Serial Interface (minimize pin connection)

HNP status/command registersHNP status/command registers


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OTG Transceiver

Block Diagram

OTG TransceiverBlock Diagram

VBUS

ID

D+

D-

USB FS/LS

Transceiver

Charge PumpRegulator

VBUS

Pulsing &

Detector

VCC

IntegratedResistors

3.3V

3.3V

USB FS/LS

Transceiver

Interfacing

Signals

HNP

Registers

Serial

Interface


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AgendaAgenda

!! VVBUSBUS input and output specinput and output spec






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Frequency AccuracyFrequency Accuracy

!! PeripheralsPeripherals

FS: 12FS: 12 MbitMbit/s +//s +/-- 2,5002,500 ppmppm

LS: 1.5LS: 1.5 MbitMbit/s +//s +/-- 15,00015,000 ppmppm

May use low cost resonatorsMay use low cost resonators

!! DualDual--role devicesrole devices

Host (FS/HS): +/Host (FS/HS): +/-- 500500 ppmppm

"" (see section 7.1.11 of USB 1.1/2.0 spec)(see section 7.1.11 of USB 1.1/2.0 spec)

Must use crystalsMust use crystals

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Jerome Tija