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2.3. USB interface
The M14Q2 module complies with USB 2.0 high-speed protocol. The USB input/output lines follow USB
2.0 specifications.
Table 4.
Signals of the USB interface
The layout design of this circuit on the host board should comply with the USB 2.0 high-speed protocol.
Layout suggestion:
Differential impedance: 90 Ω
Space to other signals should be at least 20 mils
Intra-lane length difference should be less than 150 mils
Maximum length for each trace:150 mm
Signals lengths on M14Q2 are tuned as below:
Function Net
Length (mil)
USB
USB_Dp
545.54
USB_Dn
503.04
Name
Description
Input/Output
(Direction to module)
Voltage Level (V)
Min.
Typ.
Max.
D+
USB data positive
(low-/full-speed)
Input High
2
3.3
3.6
Input Low
0
0.8
Output High
2.8
3.3
3.6
Output Low
0.3
USB data positive
(high-speed)
Input High
0.3
0.44
Input Low
0
0.01
Output High
0.36
0.38
0.44
Output Low
0
0.01
D–
USB data negative
(low-/full-speed)
Input High
2
3.3
3.6
Input Low
0
0.8
Output High
2.8
3.3
3.6
Output Low
0.3
USB data negative
(high-speed)
Input High
0.3
0.44
Input Low
0
0.01
Output High
0.36
0.38
0.44
Output Low
0
0.01
