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© 2021 ROHM Co., Ltd.
No. 64AN082E Rev.001
Oct. 2021
Application Note
BD91N01NUX Function Description
Type-C Connection Detection
When a connection is established with the Source
device and VBUS is equal or greater than VUVREL and
the voltage of CC1 and CC2 are within 0.25V and 2.18V
as defined in the Type-C standard, the product outputs
the connection result via TCC1 and TCC0 after one
Detection Data Invalid Time t
1.
TCC1 and TCC0 also change with respect to the change
in CC1 and CC2 after the connection, but this situation
shall not occur and should not affect the system in an
actual case according to Type-C standard.
When connected to a Type-C/PD device, a PD source
communicates with CC1 or CC2 for a specific duration
depending on its voltage. This communication does not
affect the system because the product has a dedicated
filter to ignore these signals.
The other charging standards, outside of
Type-C standard
This product only supports Type-C and does not support
vendor-specific charging such as DCP / CDP in BC1.2
and any proprietary charging methods like Quick
Charge. If connected, the product interprets it like it is
connected to a standard USB port through a standard-
compliant Type-A to C cable, then turns on the Pch-
MOS FET on the VBUS power line.
USB-IF had released BC1.2 Standard as official, co-
existing with Type-C. The detected BC1.2 port (i.e.,
DCP or CDP) can allow the sink to draw current up to
1.5A exceeding the Type-C default current capability.
In this case, the external BC1.2 port detector is
required.
The connection to PD Source device
The product only supports Type-
C and doesn’t support
USB PD. But USB PD standard assumes USB Type-C,
so the device detects and interprets the PD source
device according to the USB Type-C standard.
In this case, the device informs the asserted Rp by the
PD source to a system via both TCC0 and TCC1 as
well as the connection to Type-C source.
The connection via Type-A to C Cable
This product supports connection via Type-A to C cable.
Type-A to C cable has a built-in Rp in its Type-C plug.
In addition, the Rp is the resistor that asserts USB
default current according to Type-C standard for it not
to draw excess current from Source. Therefore, when
connected, TCC1 and TCC0 is TCC1=L, TCC0=H,
which indicates USB default.
If a Type-B to C cable is connected, the product cannot
boot up since the Type-B side port does not supply
power to the VBUS.
Table 5 shows the representative devices and
connection results via TCC0 / TCC1.
Table 5. The results of the connection detection to the
representative devices.
Connected device
Cable
TCC1
TCC0
Source Type-C Default*
Type-C
L
H
Source Type-C 1.5A
H
L
Source Type-C 3.0A
H
H
Source Type-C USB PD
H
H
Sink Type-C
L
L
Sink Type-C USB PD
L
L
Legacy-A (with BC1.2)
Type-A to C
L
H
Legacy-B
Type-B to C
L
L
*Type-C default is according to implemented USB standard version.
The device is designed with an assumption that a
Type-A to C cable to be used is Type-C standard
compliant and has a 56k
Ω Rp to indicate USB default.
ORIENT function
The ORIENT function is used to determine the
direction of the normal/flip side of the Type-C cable
and determine its pin assignment for USB
communication. The ORIENT terminal asserts “L” upon
startup and maintains it if CC1 is connected, while it is
“H” if CC2 is connected.
Basically, this function can be used to determine the
assignment of high-speed operating signals from
USB3.x or later. The Type-C standard allows D+ (Dp1 /
Dp2) terminals and D- (Dn1 / Dn2) terminals, which is
used for USB2.0 LS/FS/HS communication, to be
shorted to each other near the Type-C receptacle.
