Application information

STCC2540

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DocID024711 Rev 6

5.1

Supported modes

For more information refer to Section 5.4: State machine.

The STCC2540 device supports the following modes:

•

SDP BC1.2

•

CDP BC1.2

•

SDP with remote wakeup for all USB devices

•

CDP with remote wakeup for low-speed USB devices with automatic transition to DCP

auto mode if a full-speed/high-speed USB device attached or after a USB device

detached.

•

DCP auto-detect: this mode permits auto-detection of charging modes between DCP

BC1.2 (shorted D+, D-) and divider charging mode. It also supports BlackBerry

charging mode and can charge legacy devices and Korean tablets.

•

Forced DCP BC1.2 mode

•

Forced DCP divider mode

The auto-detect mode starts in divider mode. If charging negotiation attempt is detected,

to initialize the proper BC1.2 handshake process. If the BC1.2 device is detached, the circuit

automatically returns to divider mode after a 10 s (typ.) timeout.

Note:

From an application point of view it means that after removing one device the user should

wait for approx. 15 s before attaching another device.

Selection between these modes is done through the CTLx control pins. The CTLx pins may

be controlled by the host in different ways:

•

GPIO from embedded controller

•

Hardware signals from USB host controller (SLP_S3#, SLP_S4#) and AC_adapter

signal from embedded controller

•

Hardware signals SUSPEND from embedded controller and AC_ADAPTER.

Host state

CTL1 CTL2 CTL3

Mode description

0

0

0

Device off, output discharge

11

0

SDP

S0, S1, (S3)(2)

1

1

1

CDP BC1.2 with charging detection.

S3, (S0, S1)(2)

0

1

0

SDP with remote wakeup for all USB devices

S3

0

1

1

CDP with remote wakeup for low-speed USB devices / DCP auto mode for

full-speed or high-speed USB devices or after a USB device detached.

S4, S5

0

0

1

DCP auto-detect mode without remote wakeup, with charging detection

S4, S5

1

0

1

Forced DCP divider mode with charging detection

S4, S5

1

0

0

Forced DCP BC1.2 mode with charging detection

1. On the transition from the CTLx = 111 to CTLx = 001, a synchronous transition of the CTL1 and CTL2 must be ensured.

2. See Section 5.2 for further information.