Datasheet

DocID024711 Rev 5 13/33
STCC2540 Application information
33
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,
there is an automatic transition to DCP BC1.2 mode. It is preceded by V
BUS
discharge pulse
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 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.
Table 5. Truth table control pins CTLx
(1)
Host state CTL1 CTL2 CTL3 Mode description
0 0 0 Device off, output discharge
S0, S1, (S3)
(2)
110SDP
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.