SMSC USB3503, Руководство пользователя

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USB3503 Evaluation Board Manual
SMSC USB3503 EVB 4 Revision 1.0 (08-22-11)
USER MANUAL
The USB3503 EVB also has three switches to manually control the RESET_N and HUB_CONNECT
inputs to the part.
Figure 3.3 shows the location of the test points (Red) and switches (Yellow).
The USB3503 SCL, SDA, RESET_N, HUB_CONNECT and INT_B pins are also exposed on the J1
header. These pins are compatible with the Total Phase Aardvark pinout, where pin 1 of the Aardvark
connector connects to pin 1 of header J1 (Refer to
Figure 4.1 for the proper way to connect the
Aardvark). The INT_N pin is also connected to LED1 to indicate that an interrupt has occurred. The
LED remains lit until the interrupt is cleared, as described in the USB3503 datasheet.
3.3 Configuration Resistors
There are eight different resistors used to configure the part when the RESET_N pin transitions from
Low (0V) to High(>1.25V). These resistors are used for the REF_SEL pins. Because these resistors
and pads pull up to the 1.8V regulator, any changes to these resistors will need to be done with the
board unpowered. The resistor pads are laid out in a manner that prevents the pull-up resistors from
being populated at the same time as the pull-down resistors, as shown in
Figure 3.4 . The following
tables show the proper configuration resistor population requirements for the desired results, the
resistor values should match those found in
Section 6, "USB3503 EVB Bill of Materials" .
Note: The Y1 Oscillator will need to be replaced with the proper frequency if the REF_SEL pins are
altered. Refer to
Section 6, "USB3503 EVB Bill of Materials" for recommended oscillator
specifications.
Figure 3.3 Test points, Switches, Header and LED
Table 3.1 REF_SEL Options
R18 R21 R27 R30 REFCLK(MHZ)
EMPTY EMPTY INSTALL INSTALL 38.4
EMPTY INSTALL INSTALL EMPTY 26.0 (Default)
INSTALL EMPTY EMPTY INSTALL 19.2
TP2
TP1
J 1
Pin1
LED1
HUB_CONNECT
RESET
TP3
TP6
NOT USED