6/10
© 2021 ROHM Co., Ltd.
No. 64AN082E Rev.001
Oct. 2021
Application Note
BD91N01NUX Function Description
Therefore, the architecture can allow a system not to
implement any multiplexor for USB2.0 data lines.
A system can also utilize the ORIENT function for
multiplexing USB2.0 signal lines due to PCB layout
constraints, as shown in Figure 2.
VBUS
CC1
CC2
BD91N01NUX
CC1
CC2
VB
ORIENT
TCC0
TCC1
VDDIO
SWMONI
VSRC
IO Power
Dp1
USB
Type-C
Receptacle
SoC
U
S
B
P
e
ri
p
h
e
ra
l
BD11600NUX
1D-
D-
1D+
D+
2D-
2D+
OE
S
Dn1
Dp2
Dn2
G
PI
O
GPIO
SWDRV
Figure 2. An example for USB2.0 signal multiplexing
SWMONI Function
SWMONI
function constantly asserts “H” whenever
SWDRV turns on. Therefore, it can be used for
detecting the power supplied from the Source, to the
system. The signal can also be applied as an enable
input on POL that generates internal power, or on any
GPIOs in an MCU to control internal signals.
Current detection by TCC0/TCC1
As explained in the following paragraph, this product
has no current limitation or protection according to
asserted TCC1 and TCC0. A separate system shall
control the current limit depending on the Source
device.
TCC0 and TCC1 can be utilized to notify the
information regarding the current capability of the
connected Source device. Referring to the current
capability defined by TCC0 and TCC1, charging
current and overcurrent protection settings can be set
to chargers and POL via MCUs and logic components.
In the case of the default current in USB standard,
there is no method for the Type-C architecture to
specify the USB default current. Therefore, a system
shall determine the current limitation according to the
USB version of the implemented USB PHY. Note that
for USB3.2 and later, these standards require Type-C
port and USB Power Delivery, so it does not fall into
this category.
Table 6. The definition of default current in USB.
USB Standard
Current limitation
Before enumeration
regardless of USB1.0 to
3.1
100mA
USB1.x and 2.0
500mA
USB3.0 and 3.1*
900mA
*USB3.2 or later requires Type-C 1.5A as its default.
The determined current capability by TCC0 and TCC1
indicates the maximum current capability of the Source
device. The minimum power consumption and actual
power consumption by the Sink device should be less
than the capability of the Source.
In addition, this product always turns on the Pch-MOS
FET of the VBUS power line and powers the system if
there is a connected Source device. Therefore, it is
necessary for a system to limit the power consumption
from VBUS if the power supplied by the detected
Source device is less than the minimum operating
power required by the Sink.
Table 7. The power limitation between Source and Sink
Connected device
Cable
Max power of a Sink
Source Type-C Default*
Type-C
USB2.0: 2.5W
USB3.x: 4.5W**
Source Type-C 1.5A
7.5W
Source Type-C 3.0A
15W
Source Type-C USB PD
15W
Legacy-A (with BC1.2)
Type-A to C
7.5W*
*BC1.2 detector is required in addition.
**1.5A is required as default on USB3.2 or later
