XR22804 Datasheet, PDF (5/47 Pages) Exar Corporation – Hi-Speed USB to 10/100 Ethernet Bridge with 4 UARTs

Pin Configuration
XR22804
E30/RXD/RWKD# 1
E31/TXD 2
VBUS_SENSE 3
REXT 4
E29/RTSD#/RS485D/GD5 5
E28/CTSD#/GD4 6
CAP1 7
GND 8
USBD- 9
USBD+ 10
VCC 11
E26/DSRD#/GD2 12
ETH_SPD 13
E27/DTRD#/GD3 14
Exar
XR22804
E_PAD
42 E7/TXA
41 E6/RXA/RWKA#
40 GND
39 E9/CDB#/GB1
38 E8/RIB#/RWKB#/GB0
37 E18/DSRC#/GC2
36 GND
35 CAP2
34 E19/DTRC#/GC3
33 ETH_LINK
32 E16/RIC#/RWKC#/GC0
31 E17/CDC#/GC1
30 E1/CDA#/GA1
29 E0/RIA#/RWKA#/GA0
Top View
Pin Assignments
Pin No.
Pin Name
1
E30/RXD/RWKD#
2
E31/TXD
3
VBUS_SENSE
4
REXT
5
E29/RTSD#/RS485D/GD5
Type
I/O
I/O
I
I
I/O
Description
Enhanced general purpose IO, or UART channel D RX data, or remote wakeup. Defaults to
UART RX data.
Enhanced general purpose IO, or UART channel D TX data. Defaults to UART TX data.
VBUS Sense input. In self-powered mode, the VBUS from the USB connector needs to be
connected to this pin through a voltage divider circuit (VBUS = 5V, VBUS_SENSE = 3.3V
input) using large resistance values to minimize power. It should also be decoupled by a
0.1uF capacitor. This feature may be enabled via the OTP whenever the hub function is con-
figured for self-powered mode. The VBUS_SENSE input is used to disable the pull-up resis-
tor on the USBD+ signal when VBUS is not present. In bus-powered mode, this pin is ignored.
Connect externally using short trace to 226 ohm 1% resistor to ground
Enhanced general purpose IO, or UART channel D Request to Send, or channel D auto-
RS485 half-duplex enable, or general purpose IO. Defaults to UART GPIO input except when
XR22804 is used with CDC-ACM driver. Refer to Automatic RTS/CTS Hardware Flow Control
section on page 15 or Auto RS-485 Half-Duplex Control on page 16.
© 2015 Exar Corporation
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exar.com/XR22804
Rev 1B