Hardware Configuration
2014 Microchip Technology Inc.
DS50002252A-page 13
2.1.4
Power Source – Self-Powered
The EVB-USB3503 QFN only supports self-powered operation and is powered by one
+5 VDC regulated external power supply. The +5 VDC, 4 A power supply plugs into the
board via a 2.1 mm connector (J3). The external power supply controls the on board
+3.3 VDC voltage regulator and on board +1.8 VDC voltage regulator. The on board
+3.3 VDC voltage regulator feeds VBAT on the USB3503. The on board +1.8 VDC volt-
age regulator feeds VDD_CORE_REG on the USB3503. The USB3503 also has an
internal on-chip1.2 V regulator to power the digital logic core.
To supply 3.3 VDC externally, remove resistor R1 and connect a 3.3 VDC voltage sup-
ply to test point TP2
.
To supply 1.8 VDC externally, remove resistor R8 and connect a 1.8 VDC voltage sup-
ply to test point TP3.
The USB3503 can also function with a single power supply; to do this remove R8 and
place a 0 Ohm 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.
summarizes the different power options and defines what resistors must be
populated for each configuration.
shows the locations of the back-side
resistors that are used to configure the different power options.
FIGURE 2-3:
CLOCK FREQUENCY SELECTION REGISTERS
TABLE 2-2:
VBAT AND VDD_CORE_REG VOLTAGE SOURCE CONTROL
VBAT Source
VDD_CORE_REG Source
R1
R8
R9
On Board Regulator
On Board Regulator
Install
Install
Empty
External (TP2)
On Board Regulator
Empty
Install
Empty
External (TP2)
External (TP3)
Empty
Empty
Empty
On Board Regulator
VDD33_BYP
Install
Empty
Install
External (TP2)
VDD33_BYP
Empty
Empty
Install
