DocID024781 Rev 1

3/14

AN4308

Management of CTLx pins to select operating mode

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Management of CTLx pins to select operating mode

The selection between the SDP, CDP and DCP operating modes is done through a set of

control signals. The STCCxxxx devices have 3 logic inputs, the CTLx to select the suitable

operating mode in each platform power state (S0 to S5). The combination of these 3 pins

provides the following modes:

These pins may be controlled in different ways and depending on control types some

combinations are useless.

Table 1. CTLx truth table (assuming EN = 1, ATTACH_EN = 0)

Suitable

power state

CTL1 CTL2 CTL3

Mode

Advantages / use case

S0, S3

x

1

0

SDP with full remote wake-

up support

If NB is on battery and the battery charge is low,

it may be safer not to provide high current for

All PDs attached before transition from S0 to S3

are allowed to wake up the host to S0.

S0

1

1

1

CDP

NB can supply high current to PD

S3

0

1

1

CDP with remote wake-up

support for low-speed PDs

DCP auto for full-speed

and high-speed PDs

Low-speed PDs attached before transition S0 to

S3 are allowed to wake up the host to S0.

Full-speed and high-speed devices are charged

in S3 state.

S4/S5

0

0

1

Autodetect DCP mode

NB can charge PD with high current even if NB

is OFF (high power SMPS ON). The most

flexible, recommended charging mode.

S4/S5

1

0

0

Forced DCP BC1.2 mode

NB can charge PD with high current even if NB

is OFF (high power SMPS ON). Standardized

USB charging mode enhanced to support also

Korean tablet PDs.

S4/S5

1

0

1

Forced DCP divider mode

NB can charge PD with high current even if NB

is OFF (high power SMPS ON). Proprietary

charging mode for Apple PDs.

Any, but

mostly S4/S5

00

0

OFF

If NB battery is low, NB can stop charging

process using either this combination or EN pin.

1. PD stands for portable device, NB for notebook. LS stands for low-speed PDs, FS for full-speed PDs and HS for high-speed

PDs.