FUSB302B
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6
CONFIGURATION CHANNEL SWITCH
The FUSB302B integrates the control and detection
functionality required to implement a USB Type-C host,
device or dual-role port including:
• Device Port Pull-Down (R
D
)
• Host Port Pull-Up (I
P
)
• VCONN Power Switch with OCP for Full-Featured
USB3.1 Cables
• USB BMC Power Delivery Physical Layer
• Configuration Channel (CC) Threshold Comparators
Each CC pin contains a flexible switch matrix that allows
the host software to control what type of Type-C port is
implemented. The switches are shown in Figure 6.
Figure 6. Configuration Channel Switch Functionality
BMC
I/O
DAC/
Comparator
PWDNx
Reg
VCONN_CCx
Reg
Current
Source
Pull−ups
MEAS_CCx
Reg
TXCCx
Reg
PU_ENx
Reg
5.1K
VCONN_SWITCH
VCONN
MEAS_CC_SWITCH
TX_BMC_SWITCH
PULLUP_SWITCH
PULLDOWN_SWITCH
CC
X
TYPE-C DETECTION
The FUSB302B implements multiple comparators and
a programmable DAC that can be used by software to
determine the state of the CC and VBUS pins. This status
information provides the processor all of the information
required to determine attach, detach and charging current
configuration of the Type-C port connection.
The FUSB302B has three fixed threshold comparators
that match the USB Type-C specification for the three
charging current levels that can be detected by a Type-C
device. These comparators automatically cause BC_LVL
and COMP interrupts to occur when there is a change of
state. In addition to the fixed threshold comparators, the host
software can use the 6-bit DAC to determine the state of the
CC lines more accurately.
The FUSB302B also has a fixed comparator that monitors
if VBUS has reached a valid threshold or not. The DAC can
be used to measure VBUS up to 20 V which allows the
software to confirm that changes to the VBUS line have
occurred as expected based on PD or other communication
methods to change the charging level.
Detection through Autonomous Device Toggle
The FUSB302B has the capability to do autonomous DRP
toggle. In autonomous toggle the FUSB302B internally
controls the PDWN1, PDWN2, PU_EN1 and PU_EN2,
MEAS_CC1 and MEAS_CC2 and implements a fixed DRP
toggle between presenting as a SRC and presenting as
a SNK. Alternately, it can present as a SRC or SNK only and
poll CC1 and CC2 continuously.
