UCS81003 datasheet(40/108 Pages) MICROCHIP

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UCS81003

DS20005334A-page 40

 2014 Microchip Technology Inc.

9.0

ACTIVE STATE

9.1

Active State Overview

The UCS81003 has the following modes of operation in

the Active state: Data Pass-Through, BC1.2 DCP,

BC1.2 SDP, BC1.2 CDP and Dedicated Charger

Emulation Cycle. The current limiting mode depends

on the Active mode behavior (see Table 9-2).

9.2

Active Mode Selection

The Active mode selection is controlled by three

controls: EM_EN, M1 and M2, as shown in Table 9-1.

9.3

BC1.2 Detection Renegotiation

The BC1.2 specification allows a charger to act as an

SDP, CDP or DCP and to change between these roles.

To force an attached portable device to repeat the

charging detection procedure, VBUS must be cycled. In

compliance with this specification, the UCS81003

automatically cycles VBUS when switching between the

BC1.2 SDP, BC1.2 DCP and BC1.2 CDP modes.

9.4

Data Pass-Through

(No Charger Emulation)

When commanded to Data Pass-Through mode,

UCS81003 will close its USB high-speed data switch

to allow USB communications between a portable

device and host controller and will operate using Trip

Current Limiting. No charger emulation profiles are

applied in this mode. Data Pass-Through mode will

persist until commanded otherwise by the M1, M2

and EM_EN controls.

9.5

BC1.2 SDP

(No Charger Emulation)

When commanded to BC1.2 SDP mode, UCS81003

will discharge VBUS, close its USB high-speed data

switch to allow USB communications between a

portable device and host controller, and will operate

using Trip Current Limiting. No charger emulation

profiles are applied in this mode. BC1.2 SDP mode will

persist until commanded otherwise by the M1, M2,

EM_EN and PWR_EN controls.

9.6

BC1.2 CDP

When BC1.2 CDP is selected as the Active mode,

UCS81003 will discharge VBUS, close its USB

high-speed data switch (by default), and apply the

BC1.2 CDP charger emulation profile which performs

handshaking per the specification. The combination of

the UCS81003 CDP handshake along with a standard

USB host comprises a charging downstream port. In

BC1.2 CDP mode, there is no emulation timeout.

If the handshake is successful, the UCS81003 will

operate using Constant Current Limiting (variable

slope). If the handshake is not successful, the

UCS81003 will leave the applied CDP profile in place,

leave the high-speed switch closed, enable Constant

Current Limiting, and persist in this condition until

commanded otherwise by the M1, M2, EM_EN and

PWR_EN controls.

TABLE 9-1:

ACTIVE MODE SELECTION

EM_EN

Active mode

Dedicated Charger

Emulation Cycle

Data Pass-Through

BC1.2 DCP

BC1.2 SDP - Note 1

Dedicated Charger

Emulation Cycle

Data Pass-Through

BC1.2 CDP

Note 1:

BC1.2 SDP behaves the same as the

Data Pass-Through mode with the

exception that it is preceded by a VBUS

discharge when the mode is entered per

the BC1.2 specification.

Note 1: If it is desired that the Data Pass-Through

mode operates as a traditional/standard

port power switch, the S0 control should be

set to ‘0’ to allow the port power switch to

be closed without requiring an Attach

Detection event. When entering this mode,

there is no automatic VBUS discharge.

2: When the M1, M2 and EM_EN controls

are set to ‘0’, ‘1’, ‘0’ or to ‘1’, ‘1’, ‘0’

respectively, Data Pass-Through mode

will persist if the PWR_EN control is

disabled; however, the UCS81003 will

draw more current. To leave the Data

Pass-Through

mode,

the

PWR_EN

control must be enabled before the M1,

M2 and EM_EN controls are changed to

the desired mode.

Note:

If it is desired that the BC1.2 SDP mode

operates as a traditional/standard port

power switch, the S0 control should be set

to ‘0’ to allow the port power switch to be

closed

without

requiring

Attach

Detection event.

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