UCS1002-2 Datasheet, PDF (41/114 Pages) SMSC Corporation – Programmable USB Port Power Controller with Charger Emulation

5.1.3 Detect State Operation
Programmable USB Port Power Controller with Charger Emulation
Datasheet
Power State
Dummy read returns invalid data
SMBus Read
and places device in temporary
Read returns valid data
Active state
S
0101_111
0
A 0001_0000
AS
0101_111
1
A
invalid dataN P
S
0101_111
0
A 0001_0000 A S
0101_111
1
A
valid data N P
Sleep
tSMB_WAKE
temporary Active state
(not all functionality available)
tIDLE_SLEEP
Sleep
Figure 5.6 Wake Via SMBus Read with S0 = ‘0’
When the UCS1002 is in the Detect state, the port power switch will be disabled. The high-speed
switch is also disabled by default. The VBUS output will be connected to the VDD voltage by a
secondary bypass switch (see Chapter 8, Detect State).
There is one non-recommended configuration which places the UCS1002 in the Detect state, but
V_BUS will not be discharged and a portable device attachment will not be detected. For the
recommended configurations, see Table 5.1, "Power States Control Settings".
 NOT RECOMMENDED: PWR_EN is enabled, S0 = ‘1’, and M1, M2, and EM_EN are all ‘0’.
There are two methods for transitioning from the Detect state to the Active state: automatic and host-
controlled.
5.1.3.1
Automatic Transition from Detect to Active
For the Detect state, set S0 to ‘1’, enable PWR_EN, set the EM_EN, M1, and M2 controls to the
desired Active mode (Table 9.1, "Active Mode Selection"), and supply VS > V_{S_UVLO}. When a portable
device is attached and an Attach Detection event occurs, the UCS1002 will automatically transition to
the Active state and operate according to the selected Active mode.
5.1.3.2
Host-Controlled Transition from Detect to Active
For the Detect state, set S0 to ‘1’, set the EM_EN, M1, and M2 controls to the desired Active mode
(Table 9.1, "Active Mode Selection"), and configure one of the following: 1) disable PWR_EN and
supply VS, or 2) enable PWR_EN and don’t supply VS. When a portable device is attached and an
Attach Detection event occurs, the host must respond to transition to the Active state. Depending on
the control settings in the Detect state, this could entail 1) enabling PWR_EN or 2) supplying VS above
the threshold.
APPLICATION NOTE: If S0 is '1', PWR_EN is enabled, and VS is not present, the A_DET# pin will cycle if the
current draw exceeds the current capacity of the bypass switch.
5.1.3.3
State Change from Detect to Active
When conditions cause the UCS1002 to transition from the Detect state to the Active state, the
following occurs:
1. The Attach Detection feature will be disabled; the Removal Detection feature remains enabled,
unless S0 is changed to ‘0’.
2. The bypass switch will be turned off.
3. The discharge switch will be turned on for t_DISCHARGE.
SMSC UCS1002
41
DATASHEET
Revision 1.4 (07-16-13)