Revised Wakeup and Sleep Scheme for PoDL. Andrew Gardner Linear Technology

Transcription

1 Revised Wakeup and Sleep Scheme for PoDL Andrew Gardner Linear Technology

2 Presentation Objectives Propose a revised wakeup and sleep scheme for PoDL that addresses concerns of economic and technical feasibility presented at the IEEE802.3bu meeting in July Present changes to baseline text and state diagrams required to implement the proposal. 2

3 Issues with Wakeup and Sleep Scheme in D1.2 The current sense dynamic range requirements of 500 and 300, respectively, for the proposed POWER_ON and SLEEP states are too big. Given the ultra-low currents that will be required by a sleeping PoDL PD, PoE style DC disconnect is not technically feasible. V Sleep and V Sig need to be defined so as to be compatible with the V ON and V OFF thresholds required for the unregulated 12V automotive power class. 3

4 New Wakeup and Sleep Scheme Proposal Revert to MPS requirements that are comparable with what is currently being proposed in 802.3bt: 10mA < I Hold, T MPS > 60ms, 300ms < T MPDO < 400ms Instead of removing power when T MPDO expires, the PSE will reduce voltage at the PI to 3.3V with limited output current. This low power level should not present a hazard to the PD if it is hot-plugged. The PD constant voltage detection signature needs to be changed to be greater than V Sleep and less than V ON for the unregulated 12V class. The PD signature is enabled by a falling-edge through V sig_enable and disabled by a rising-edge through V sig_disable. A wakeup signature current switched in shunt with the detection signature device allows a sleeping PD to request power-up. A PD that is hot-plugged into a sleeping PI also presents the wakeup current when exiting RESET in order to request initial power-up. 4

5 PD Detection and Wakeup Signature Timing Waveforms V MDI/PI(PD) V sig_disable V sig_enable V reset Detection Signature enabled? I wakeup enabled? PD Reset? 5

6 Thresholds for V sig_disable, V sig_enable, V Sleep, & Unregulated 12V Class V On & V Off PD signature disabled by a rising-edge transition through V sig_disable Range for PD detection signature PD signature is enabled by a fallingedge transition through V sig_enable Range of V Sleep Symbol Voltage % from avg PD V On,max 12V unreg & V sig_disable,max % V bad_hi,max(pse) % V sig,max(pse) 4.7 9% V sig,max(pd) % V sig,nom(pd) % V sig,min(pd&pse) % V bad_low,min(pse) % PD V Off,min 12V unreg & V sig_enable,min % V sleep,max(pse) % V sleep,nom % V sleep,min(pse) % V sleep,min(pd) % * See Annex A for latest power class table. 6

7 PD Detection and Wakeup Current Signatures Constant voltage detection signature moves from 3V to 4.3V to make room for V Sleep. A resistor connected in shunt with the detection signature creates a wakeup current signature when a sleeping PD needs to be powered-up or when a PD exits RESET. Detection signature is enabled by a falling edge through V Sig_enable. Detection signature and wakeup current signature are disabled by a rising edge through V Sig_disable. Simplified Schematic of Proposed Detection and Wakeup Signature 7

8 PD Initiated Sleep and Wakeup Transition Waveforms (Unregulated 12V Class) PD WAKE PD INH t POWER_DLY(PD) I PD I hold,min I wakeup,max I wakeup,min V On & V sig_disable V PI(PD) V Off & V sig_enable V Sleep,max t MPDO(PSE) t WAKEUP(PSE) V Sleep,min 8

9 PSE Wakeup Forwarding Waveforms (Unregulated 12V Class) PSE WAKE PD INH t POWER_DLY PD WAKE I PD I wakeup,max I wakeup,min I Hold V On & V sig_disable V PI(PD) V Off & V sig_enable V Sleep,max V Sleep,min 9

10 Proposed Changes to Baseline Text Overview f) A method of scaling supplied power voltage back to the detect sleep level when normal operating power voltage is no longer requested or required Power sourcing equipment (PSE) To remove normal operating voltage power when no longer requested or required, returning to the searching state transitioning to the SLEEP state An unplugged link segment is one instance when normal operating voltage power is no longer required. In addition, voltage and power classification mechanisms exist via SCCP to provide the PSE with detailed information regarding the requirements of the PD and vice versa. 10

11 Proposed Changes to Baseline Text Cont d Overview Prior to application of power of normal operating voltage at the PI, the PSE shall performs detection in order to verify that a valid PD is present. A PSE may communicate with the PD prior to the application of normal operating voltage using SCCP. After normal operating voltage has been applied, the PSE monitors the PI for a valid maintain power signature (MPS) from the PD. In the event a valid MPS is not present, the PSE reduces the voltage at the PI to the range of V Sleep. If an external wakeup request is received or if a valid wakeup current signature is detected at the PI, the PSE confirms that a valid PD is still present by re-performing detection before re-applying normal operating voltage to the PI. 11

12 Proposed Changes to Baseline Text Cont d Output Current A PSE operating in the POWER_ON state shall consider a PD sleep request valid if I Port averaged over a sliding window t Sleep wide is less than or equal to I Sleep min. A PSE operating in the POWER_ON state shall enter the SLEEP_SETTLE state if a valid MPS is not present at the PI. A PSE operating in the SLEEP_SETTLE state shall discharge the PI to the range of V Sleep with a current greater than I discharge Wakeup current signature detection A PSE operating in the SLEEP state shall consider a PD wakeup request valid if I Port is greater than I Wakeup min is in the valid range of I wakeup for a minimum of t Wakeup (see Table 104-3). A PSE operating in the SLEEP state shall consider a PD wakeup request invalid if I Port is greater than I wakeup_bad_hi or less than I wakeup_bad_lo. A PSE may consider a PD wakeup request valid or invalid if I port is in the band between I wakeup_bad_hi and I wakeup max or the band between I wakeup min and I wakeup_bad_lo. 12

13 Proposed Changes to Baseline Text Cont d Turn off time The specification for T Off in Table shall apply to the discharge time from V PSE in the POWER_ON state to V Off V Sleep with a test resistor of TBD kω ±1% attached to the PI. In addition, it is recommended that the PI be completely discharged when the PSE is not enabled turned off. T Off starts when V PSE drops 1 V below the steady-state normal operating voltage value after the pi_powered variable is cleared. T Off ends when V PSE V Off V Sleep max. The PSE remains in the IDLE state as long as the average voltage across the PI is V Off. The IDLE state is the state when the PSE is not in detection, classification, or normal powering states PSE power removal Power shall be removed from the PSE PI in the absence of the PD Maintain Power Signature while the PSE is operating in the SLEEP state. Power Normal operating voltage shall be removed from the PSE PI in the absence of the PD Maintain Power Signature while the PSE is operating in the SLEEP POWER_ON state. 13

14 Proposed Changes to Baseline Text Cont d PSE Maintain Power Signature (MPS) requirements A PSE shall consider the MPS to be present if I Port averaged over a sliding window T MPS wide is greater than or equal to I Hold max. A PSE shall consider the MPS to be present if I Port is greater than or equal to I Hold max for a minimum of T MPS. A PSE may consider the MPS to be either present or absent if I Port averaged over a sliding window T MPS wide is in the range of I Hold. A PSE may consider the MPS to be either present or absent if I Port is in the range of I Hold. A PSE shall consider MPS to be absent if I Port averaged over a sliding window TMPS wide is less than or equal to I Hold min. A PSE shall consider MPS to be absent if I Port is less than or equal to I Hold min. Power Voltage shall be removed from reduced to the range of V Sleep at the PI when the MPS has been absent for a duration greater than T MPDO. 14

15 Proposed Changes to Baseline Text Cont d Item Parameter Symbol Unit Min Max Class Typ e 1a 1 DC output voltage during POWER_ON state V PSE(PON) V Class V PSE(min) Class V PSE(max) 1b DC output voltage during sleep V PSE(SLP) V 4 V off(min) Additional Information See and Table Turn off voltage DC output voltage during SLEEP state 13 PD Maintain Power Signature dropout time limit 14 Maintain Power Signature window time limit V OFF V Sleep V TBD 3.15 TBD 3.5 TBD See T MPDO s See t MPS ms MPS Current Threshold I Hold A Sleep current threshold I Sleep ua 17 Sleep current threshold sliding window t Sleep ms Valid wakeup current signature range 17 Invalid wakeup current signature high range 18 Invalid wakeup current signature low range I wakeup_ ma See I wakeup_bad_hi ma 2.5 I wakeup_bad_lo ma Restart timer delay t Restart_timer ms 100 Table PSE output requirements 15

16 Proposed Changes to Baseline Text Cont d Item Parameter Symbol Unit Min Max Additional Information 1 Open circuit voltage V OC V Short circuit current I SC ma Valid test probe current I Valid ma Valid PD detection range measured at PSE PI 8 Invalid PD detection signature high range measured at PSE PI 9 Invalid PD detection signature low range measured at PSE PI V good_pse V V bad_hi_pse V 5.15 V bad_low_pse V 3.7 Table PSE PI detection state electrical output requirements 16

17 Proposed Changes to Baseline Text Cont d Overview If the PD input voltage is less than V sig_disable, the PD shall present a constant voltage signature, defined in Section SCCP may be used for communication between the PD and PSE when V PD < V sig_disable. When the input voltage exceeds V sig_disable, the PD shall remove the constantvoltage signature from the PI and shall wait t pwr_delay before drawing power from the MDI. In the event of a PD fault or removal of the MPS, a rising V PD edge through the V on (max) threshold shall cause the PD to re-enable MDI power after a delay of t pwr_delay. A falling-edge of the PD input voltage through V sig_enable enables a constant voltage signature, defined in Section When the input voltage rises through the V sig_disable the PD disables its constant-voltage signature. A PD requests detection and wakeup while the constant voltage signature is enabled by presenting a valid wakeup current signature. SCCP may also be used for communication with the PD by the PSE when the constant-voltage signature is enabled. A rising edge through the V On threshold causes the PD to enable MDI power after a delay of t pwr_delay. A falling edge through the V Off threshold causes the PD to disable MDI power. 17

18 Proposed Changes to Baseline Text Cont d PD signature A PD shall presents a valid detection signature when V PD is less than drops below V sig_enable while it is in the DO_DETECTION state when it is requesting power via the PI, but is not powered via the PI per Figure When V PD rises through V sig_disable, a PD shall remove the current draw of the detection signature. A PD shall present a detection signature, either valid or non-valid, at the PI. The detection signature shall consists of a current limited, constant voltage per Table when measured by the PSE PD input voltage The PD shall operate in the SLEEP and WAKEUP states PD_SLEEP state with an input voltage in the range of greater than V Sleep_PD min as specified in Table

19 Proposed Changes to Baseline Text Cont d Input current During operation in the SLEEP_PENDING and SLEEP states, the PD shall not draw current averaged over a sliding window t Sleep seconds wide in the range of I Sleep in excess of I Sleep as specified in Table During operation in the WAKEUP state, the PD A PD that requires detection and power-up shall draw current in the range of I Wakeup_PD for at least t Wakeup_PD as specified in Table PD Maintain Power Signature In order to maintain power full input operating voltage, the PD shall provide a valid Maintain Power Signature (MPS) at the PI. The MPS shall draw current averaged over a sliding window TMPS wide equal to or above IHold_PD(min). The MPS shall consist of current draw equal to or above I hold_pd for a minimum duration of T MPS_PD measured at the PD PI followed by an optional MPS dropout for no longer than T MPDO_PD. PDs that do not require power full input operating voltage shall remove the current draw of the MPS from the PI. 19

20 Proposed Changes to Baseline Text Cont d Parameter Conditions Unit Min Max V good 1 3mA<I connector <10 11mA, I connector rising from 0 PD exiting RESET V I signature_limit V connector >3.5V V connector <5.15V ma V sig_disable V connector rising V V sig_enable Hysteresis V connector falling V Table Valid PD detection signature characteristics, measured at PD connector Parameter Conditions Unit Min Max V bad_hi V V bad_lo V Table Non-valid PD detection signature characteristics, measured at PD connector 20

21 Proposed Changes to Baseline Text Cont d Item Parameter Symbol Unit Min Max PD Type 8 PD Maintain Power Signature time 8 9 PD Maintain Power Signature dropout time limit 9 10 MPS current threshold limit Additional Information T MPS_PD ms 75 See T MPDO_PD ms 250 I hold_pd ma 11 See Power supply voltage during SLEEP and WAKEUP states SLEEP state current limit V Sleep_PD V V off(min) See I Sleep_PD µa 100 See Wakeup current I wakeup_pd ma V<V PD <3.5V Table PD power supply limits 21

22 PSE, State Machine Changes for Proposed Wakeup and Sleep Scheme D1.2 PSE Port State Machine Proposed PSE Port State Machine 22

23 PSE, Detection, and MPS State Machines for Proposed Wakeup and Sleep Scheme D1.2 Detection and MPS State Machines Proposed Detection and MPS State Machines 23

24 New and Modified Variables for Proposed PSE State Machines detection_done A Boolean variable indicating that a valid detection sequence has been completed prior to entering the POWER_UP state. True when a valid detection sequence has been completed. external_wakeup A Boolean variable that indicates the PSE has received an external wakeup request and shall re-detect the PD before re-applying the full operating voltage to the PI. pd_wakeup A Boolean variable that indicates the PSE has detected a valid wakeup current signature at the PI and shall re-detect the PD before re-applying the full operating voltage to the PI. pi_detecting A Boolean variable that controls the circuitry the PSE uses to detect a valid PD signature. If true, the PSE forces a voltage limited detection current and senses the voltage at the PI in order to determine if a valid PD signature is present. 24

25 New and Modified Variables for Proposed PSE State Machines pi_powered A Boolean variable that controls the circuitry the PSE uses to power the PD. If false, the PSE shall not apply power the normal operating voltage to the PI (default). If true, the PSE is applying power normal operating voltage to the PI. pi_sleeping A Boolean variable that controls the circuitry the PSE uses to power the PD. True when the PSE applies V Sleep at the PI. If true, the PSE is applying V Sleep at the PI. sleep_detected A Boolean variable indicating that the average value of IPort is less than or equal to the ISleep threshold current and that the PSE shall transition to the SLEEP state. See

26 New and Modified Timers for Proposed PSE State Machines tinrush_timer A timer used to monitor the duration of the inrush event. toff_timer A timer used to limit the time the PSE attempt to discharge the PI to the range of V sleep. If toff_timer expires during the SETTLE_SLEEP state, an error condition exists, and the port state machine enters the ERROR state. 26

27 PD State Machine Changes for Proposed Wakeup and Sleep Scheme D1.2 PD State Machine Proposed PD State Machine 27

28 New and Modified Variables for Proposed PD State Machine disconnect A Boolean variable that indicates a PD no longer requires power the normal operating voltage from the PI and has reduced its port current below the MPS threshold current, I Hold. wake wakeup A Boolean variable that indicates when a PD requires full power at the PI and when it is ready to go to sleep. True when full power is required and false when ready for sleep. 28

29 Summary A proposal for a revised wakeup and sleep scheme that addresses issues raised at the July plenary meeting was proposed. Changes to baseline text and state diagrams were presented. 29

30 30 Questions?

31 Annex A Proposed Power Class Table System Class 12V unreg 12V reg 24V unreg 24V reg 48V unreg 48V reg (Open) Show in table 104-1? (a) (b) (a) (b) (a) (b) (a) (b) (a) (b) (a) (b) V PSE_PI(max) (V) yes V PSE(min) (V) no V PSE_PI (min) (V) yes R PSE (Ω) no I PI(max) (A) yes R Loop(max) (Ω) no V PD(min) yes P VPSE (W) no P PSE (W) no P PD (W) yes K=(P VPSE -P PD )/P PSE no worst case K no SCCP Class Code (binary) (decimal) no no 1 V PSE_PI is the voltage measured at the PSE PI for all load conditions. 2 R Loop is the round trip link segment resistance. 3 P PSE is the maximum power the PSE is required to source as measured at the PI. 4 P PD is the power available at the PD PI. 31