CP2105
20
Rev. 1.1
Alternatively, if 3.0 to 3.6 V power is supplied to the VDD pin, the CP2105 can function as a USB self-powered
device with the voltage regulator bypassed. For this configuration, the REGIN input should be tied to VDD to bypass
the voltage regulator. A typical connection diagram showing the device in a self-powered application with the
The USB max power and power attributes descriptor must match the device power usage and configuration. See
application note “AN721: CP21xx Device Customization Guide” for information on how to customize USB
descriptors for the CP2105.
Figure 9. Typical Self-Powered Connection Diagram (Regulator Bypass)
Note 3
Note 2
Note 1
VBUS
D+
D-
GND
USB
Connector
Enhanced
UART
and GPIO
Signals
Standard
UART
and GPIO
Signals
CP2105
RXD_ECI
TXD_ECI
RXD_SCI
TXD_SCI
RTS_ECI
CTS_ECI
GPIO0_ECI / DTR_ECI
GPIO.1_ECI / DSR_ECI
SUSPEND / RI_ECI
NC / DCD_ECI / VPP
RTS_SCI
CTS_SCI
GPIO.1_SCI / DTR_SCI
GPIO.2_SCI / DSR_SCI
SUSPEND / RI_SCI
GPIO.0_SCI / DCD_SCI
REGIN
VDD
GND
VIO
VBUS
D+
D-
RST
1-5
F
0.1
F
VIO
4.7 k
Note 4
Note 1 : Avalanche transient voltage suppression diodes compatible with Full-speed USB should be
added at the connector for ESD protection. Use Littelfuse p/n SP0503BAHT or equivalent.
Note 2 : An external pull-up is not required, but can be added for noise immunity.
Note 3 : VIO can be connected directly to VDD or to a supply as low as 1.8 V to set the I/O interface
voltage.
Note 4 : If configuration ROM is to be programmed via USB, a 4.7
F capacitor must be added
between NC / DCD_ECI / VPP and ground. During a programming operation, the pin should
not be connected to other circuitry, and VDD must be at least 3.3 V.
Note 5 : For self-powered systems where VDD and VIO may be unpowered when VBUS is connected
to 5 V, a resistor divider (or functionally-equivalent circuit) on VBUS is required to meet the
absolute maximum voltage on VBUS specification in the Electrical Characteristics section.
3.3 V
Power
47 k
24 k
Note 5
(Optional)