SMSC USB3503, Manual

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USB3503 Evaluation Board Manual
SMSC USB3503 EVB 5 Revision 1.0 (08-22-11)
USER MANUAL
3.4 Additional Circuitry
The U1 Regulator provides 3.3V to the VBAT pin, and also supplies power to the 26MHz clock
oscillator. If a higher VBAT voltage is desired, remove
R1 and supply the power through TP2 .
The U2 Regulator provides 1.8V to the VDD_CORE_REG pin as well as providing the pull up voltage
for the digital control pins. To provide external power to the VDD_CORE_REG pin remove
R8 and
supply the power through TP3.
The USB3503 can function with a single power supply; to do this remove R8 and place a 0Ohm
resistor on R9 . This connects the VDD_CORE_REG pin to the VDD33_BYP pin allowing the
USB3503’s internal 3.3V regulator to supply the VDD_CORE_REG voltage.
Below is a summary of the different power options and what resistors need to be populated to support
these options:
INSTALL INSTALL EMPTY EMPTY 12.0
Figure 3.4 Configuration Resistors
Table 3.2 VBAT and VDD_CORE_REG source control
R1 R8 R9 VBAT SOURCE
VDD_CORE_REG
SOURCE
INSTALL INSTALL EMPTY Onboard Regulator Onboard Regulator
EMPTY INSTALL EMPTY External (TP2) Onboard Regulator
EMPTY EMPTY EMPTY External (TP2) External (TP3)
Table 3.1 REF_SEL Options
R18 R21 R27 R30 REFCLK(MHZ)