8.3.11 L1 Power Management State (Sleep) and Resume

The ISOUSB211 device supports the additional L1 or Sleep low power state defined in the USB 2.0 Link Power

Management ECN. When L1 entry is detected from the LS and FS idle state, the ISOUSB211 continues in the

LS or FS idle state, at the same time reducing internal power consumption. If L1 entry is detected from HS idle

state, the ISOSUB211 disables all high-speed circuits to reduce power consumption. The transition to the L1

low-power mode is completed within 50 µs.

Exit from L1 occurs through either Resume signaling from the host, on the upstream facing side of ISOUSB211,

or Remote Wake signaling from the peripheral on the downstream facing side of ISOUSB211 followed by

Resume signaling from the host/hub on the upstream facing side. Start of Resume or Wake are signaled by a ‘K’

state by the host or the device respectively. The end of resume is signalled by the host by driving two low-speed

bit times of SE0 followed by a 'J' state. If the port was operating in high speed before entering the low power

state, end of resume is signaled by the host by transitioning to the high speed idle state. ISOUSB211 is able to

replicate the K signaling appropriately both upstream and downstream. After Resume/Wake signaling the device

returns to LS, FS or HS idle state depending on the state it was in before entering the L1 state.

8.3.12 HS Test Mode Support

USB2.0 standards needs test mode support, where the host/hub or peripheral is expected to enter High Speed

test-modes based on commands received. ISOUSB211 is able to automatically detect test mode entry to enable

HS compliance tests.

8.3.13 CDP Advertising

The ISOUSB211 device supports CDP advertising on both downstream and upstream facing side according to

Battery Charger standard BC 1.2. CDP advertizing is useful when isolating a host or hub, to indicate to the

connected peripheral that the port is capable of supplying 1.5 A of current on VBUS. CDP advertising can be

enabled by connecting the dowsnstream side CDPENZx pin to ground (active low).

8.4 Device Functional Modes

Function Table lists the functional modes for the ISOUSB211 device.

Table 8-1. Function Table

SIDE 1

SUPPLY

VBUS1, V3P3V1

VCC1, V1P8V1 (1)

BUS1

(UD+, UD-)

SIDE 2

SUPPLY

VBUS2, V3P3V2

VCC2, V1P8V2

BUS2

(DD+, DD-)

COMMENTS

Powered

Active

Powered

Active

When both sides are powered, the state-of the bus is reflected

correctly from upstream to downstream and vice-versa.

Powered

15-kΩ PD

Powered

15-kΩ PD

Disconnected state is presented on both upstream and downstream

Powered

15-kΩ PD

Unpowered

Z

If a side is not powered, the bus lines on that side are in high-

impedance state.

Unpowered

Z

Powered

15-kΩ PD

Unpowered

Z

Unpowered

Undetermined

(1)

Powered =( (VBUSx ≥ UV+(VBUSx)) || (VBUSx = V3P3Vx ≥ UV+(V3P3Vx)) ) & ( (VCCx ≥ UV+(VCCx)) || (VCCx = V1P8Vx ≥ UV+(V1P8Vx)) ) ;

Unpowered = ( (VBUSx < UV-(VBUSx)) & (V3P3Vx < UV-(V3P3Vx)) ) || ( (VCCx < UV-(VCCx)) & (V1P8Vx < UV-(V1P8Vx)) ); X = Irrelevant; H = High

level; L = Low level; Z = High impedance

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ISOUSB211

SLLSFC5B – NOVEMBER 2021 – REVISED SEPTEMBER 2022

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