XR22801 Datasheet, PDF (5/42 Pages) Exar Corporation – Hi-Speed USB to 10/100 Ethernet Bridge

Pin Configuration
XR22801
VBUS_SENSE ¹
REXT ²
CAP1 ³
GND ⁴
USBD- ⁵
USBD+ ⁶
VCC ⁷
ETH_SPD ⁸
Exar
XR22801
E_PAD
24 E7/TX
23 E6/RX/RWK#
22 GND
21 GND
20 CAP2
19 ETH_LINK
18 E1/CD#/G1
17 E0/RI#/RWK#/G0
Pin Assignments
Pin No.
Pin Name
1
VBUS_SENSE
2
REXT
3
CAP1
4
GND
5
USBD–
6
USBD+
7
VCC
8
ETH_SPD
9
XTALOUT
10
XTALIN
© 2015 Exar Corporation
Top View
Type
I
I
I
PWR
I/O
I/O
PWR
O
O
I
Description
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 configured
for self-powered mode. The VBUS_SENSE input is used to disable the pull-up resistor 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
Connect externally to CAP2 and 3V3_OUT using short trace
Power supply common, ground
USB port differential data negative
USB port differential data positive
5.0V power supply input
Ethernet 100 Mbps Speed Indicator. Asserted high for 100 Mbps.
Crystal or buffered clock output
25 MHz +/- 50 ppm Crystal or external clock input
5 / 42
exar.com/XR22801
Rev 1B