Specifications

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Reference Guide
Interfaces
3.1.3. USB Interface
Aside from the serial interface, the Mini-B USB interface (USB slave) may also be
used to directly communicate with the modem.
Figure 20. Mini-B USB Connector
Refer to the following table for the pin description of the mini-B USB connector.
Table 16. Mini-B USB Pin Description
Pin #
Signal
Description
1
VBUS
+5V Power supply
2
D-
Differential data interface negative
3
D+
Differential data interface positive
4
ID
Not connected
5
GND
Ground
The USR3500 USB slave interface complies with USB 2.0 protocol signaling and
with USB 2.0 electrical interface.
The USB interface features:
• 480Mbit/s high-speed transfer rate
• 3.3V type compatible
• USB Soft-connect feature
• USB Download feature
• CDC 1.1 – ACM compliant
Table 17. USB Electrical Characteristics for USR3500
Parameter
I/O
Min
Typ
Max
Unit
VBUS
Input
4.75
5
V
D-, D+ (Low / Full speed)
Input High
2.00
3.30
3.60
V
Input Low
0
0.80
V
Output High
2.80
3.30
3.60
V
Output Low
0.30
V
D-, D+ (High speed)
Input High
0.30
0.44
V