USB5926CSLASHKD datasheet(35/65 Pages) MICROCHIP

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USB5926C

DS00003190B-page 35



2019 - 2021 Microchip Technology Inc.

8.3.3

USB BUS RESET

In response to the upstream port signaling a reset to the device, the device performs the following:

1. Sets default address to 0.

2. Sets configuration to Unconfigured.

3. Moves device from suspended to active (if suspended).

4. Complies with the USB Specification for behavior after completion of a reset sequence.

The host then configures the device in accordance with the USB Specification.

8.4

Link Power Management (LPM)

The device supports the L0 (On), L1 (Sleep), and L2 (Suspend) link power management states. These supported LPM

states offer low transitional latencies in the tens of microseconds versus the much longer latencies of the traditional USB

suspend/resume in the tens of milliseconds. The supported LPM states are detailed in Table 8-1.

8.5

Remote Wakeup Indicator

The remote wakeup indicator feature uses

SUSP_IND as a side band signal to wake up the host when in USB 2.0 sus-

pend. This feature is enabled and disabled via the HUB_RESUME_INHIBIT configuration bit in the hub configuration

space register HUB_CFG_3. The only way to control the bit is by configuration EEPROM, SMBus or internal ROM

default setting. The state is only modified during a power on reset, or hardware reset. No dynamic reconfiguring of this

capability is possible.

When HUB_RESUME_INHIBIT = ‘0’, Normal Resume Behavior per the USB 2.0 specification

When HUB_RESUME_INHIBIT = ‘1’, Modified Resume Behavior is enabled

8.6

Port Control Interface

Port power and over-current sense share the same pin (

PRT_CTLx) for each port. These functions can be controlled

directly from the USB hub, or via the processor. Additionally, smart port controllers can be controlled via the I2C inter-

face.

The device can be configured into one of the two following port control modes:

•

Ganged Mode - A single GANG_PWR pin controls power and detects over-current events for all downstream

ports.

•

Individual Mode - Each port has an individual PRT_CTLx pin for independent port power control and over-current

detection.

Port connection in various modes are detailed in the following subsections.

Note:

The device does not propagate the upstream USB reset to downstream devices.

TABLE 8-1:

LPM STATE DEFINITIONS

State

Description

Entry/Exit Time to L0

Suspend

Entry: ~3 ms

Exit: ~2 ms (from start of RESUME)

Sleep

Entry: <10 us

Exit: <50 us

Fully Enabled (On)

Note:

The

SUSP_IND signal only indicates the USB2.0 state.

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