C8051F380/1/2/3/4/5/6/7/C
4.2. USB
Figure 4.5 shows a typical connection diagram for the USB pins of the C8051F38x devices including a
100 Ω current-limiting resistor on the VBUS sense pin and ESD protection diodes on the USB pins. This
current-limiting resistor is recommended for systems that may experience electrostatic discharge (ESD),
latch-up, and have a greater opportunity to share signals with systems that do not have the same ground
potential. This is not a required component for most applications.
USB
Connector
VBUS
D+
D-
Signal GND
Recommended,
not required
100 ȍ
VBUS
D+
D-
SP0503BAHT or
equivalent USB
ESD protection
diodes
GND
C8051F38x Device
USB
Figure 4.5. Connection Diagram for USB Pins
4.3. Voltage Reference (VREF)
Figure 4.6 shows a typical connection diagram for the voltage reference (VREF) pin of the C8051F38x
devices when using the internal voltage reference. When using an external voltage reference, consult the
appropriate device’s data sheet for connection recommendations.
C8051F38x Device
2.42 V (out)
4.7 µF and 0.1 µF
capacitors recommended
for internal voltage
reference.
VREF
Voltage
Reference
GND
Figure 4.6. Connection Diagram for Internal Voltage Reference
36
Rev. 1.4