UCS1001 datasheet(42/59 Pages) MICROCHIP

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USB Port Power Controller with Charger Emulation

Datasheet

Revision 1.2 (05-21-12)

SMSC UCS1001

DATASHEET

Chapter 8 Active State

8.1

Active State Overview

The UCS1001 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 8.2, "Current Limit Mode Options").

8.2

Active Mode Selection

The Active mode selection is controlled by three controls: EM_EN, M1, and M2, as shown in Table 8.1.

Note 8.1

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.

8.3

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 UCS1001 automatically cycles VBUS when switching

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

8.4

Data Pass-through (No Charger Emulation)

When commanded to Data Pass-through mode, UCS1001 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.

APPLICATION NOTE: 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’. When entering this mode, there is no

automatic VBUS discharge.

Table 8.1 Active Mode Selection

EM_EN

ACTIVE MODE

Dedicated Charger Emulation Cycle

Data Pass-through

BC1.2 DCP

BC1.2 SDP - See Note 8.1

Dedicated Charger Emulation Cycle

Data Pass-through

BC1.2 CDP

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