CP2101-GMR Datasheet, PDF (12/20 Pages) Silicon Laboratories – Single-Chip USB to UART Bridge

CP2101
5. USB Function Controller and Transceiver
The Universal Serial Bus function controller in the CP2101 is a USB 2.0 compliant full-speed device with
integrated transceiver and on-chip matching and pull-up resistors. The USB function controller manages
all data transfers between the USB and the UART as well as command requests generated by the USB
host controller and commands for controlling the function of the UART.
The USB Suspend and Resume signals are supported for power management of both the CP2101 device
as well as external circuitry. The CP2101 will enter Suspend mode when Suspend signaling is detected
on the bus. On entering Suspend mode, the CP2101 asserts the SUSPEND and SUSPEND signals.
SUSPEND and SUSPEND are also asserted after a CP2101 reset until device configuration during USB
Enumeration is complete
The CP2101 exits the Suspend mode when any of the following occur: (1) Resume signaling is detected or
generated, (2) a USB Reset signal is detected, or (3) a device reset occurs. On exit of Suspend mode, the
SUSPEND and SUSPEND signals are de-asserted.
Both SUSPEND and SUSPEND temporarily float high during a CP2101 reset. If this behavior is undesir-
able, a strong pulldown (10 kΩ) can be used to ensure SUSPEND remains low during reset. See
Figure 5.1 for other recommended options.
USB
CONNECTOR
VBUS ¹
D- ²
D+ ³
GND ⁴
C1
1 µF
7
REGIN
C4
4.7 µF
C2
0.1 µF
Option 2
6 _VDD
3 _GND
8 _VBUS
5
D-
4
D+
D1 D2 D3
Option 3
CP2101
VDD
R1
4.7 kΩ
Option 1
RST
9
SUSPEND ¹²
SUSPEND
RI
11
R2
10 kΩ
2
DCD
1
DTR
28
DSR
27
TXD
26
RXD
25
RTS
24
CTS
23
(to external circuitry
for USB suspend
states)
Option 4
External RS-232
transceiver or
UART circuitry
Option 1: A 4.7 kΩ pull-up resistor can be added to increase noise immunity.
Option 2: A 4.7 µF capacitor can be added if powering other devices from the on-chip regulator.
Option 3: Avalanche transient voltage suppression diodes can be added for ESD protection.
Option 3: Use Littlefuse p/n SP0503BAHT or equivalent.
Option 4: 10 kΩ resistor to ground to hold SUSPEND low on initial power on or device reset.
Figure 5.1. Typical Connection Diagram
6. Asynchronous Serial Data Bus (UART) Interface
The CP2101 UART interface consists of the TX (transmit) and RX (receive) data signals as well as the
RTS, CTS, DSR, DTR, DCD and RI control signals. The UART supports RTS/CTS, DSR/DTR and X-On/X-
Off handshaking.
12
Rev. 1.8