Smart Module Series
SC200L_Series(Dual-band Wi-Fi)_Hardware_Design 42 / 111
The USB2 interface of the module only supports USB host mode. If you need this function, follow the
design below to add an external 5 V power supply, which can provide 500 mA current.
AW3605DNR
SW
VIN
22
μF
C2
10
μF
NM
1.0
μH
VBAT
C1
L1
R1
EN
A
G
N
D
VOUT
VOUT
NC
P
G
N
D
P
G
N
D
1
2
9
4
5
6
7
8
USB_VBUS2
GPIO_156
3
R2
10K
NM
R3
Figure 14: Reference Design for USB2 Power Supply
To ensure USB performance, please comply with the following principles while designing the USB
interface.
⚫
It is important to route the USB signal traces as differential pairs with total grounding. The impedance
of USB differential traces is 90
Ω.
⚫
Keep the ESD protection devices as close as possible to the USB connector. Pay attention to the
influence of junction capacitance of ESD protection devices on USB data traces. Typically, the
capacitance value should be less than 2 pF.
⚫
Do not route signal traces under crystals, oscillators, magnetic devices or RF signal traces. Route the
USB differential traces in inner-layer with ground shielding on not only the upper and lower layers but
also the right and left sides.
⚫
Make sure the trace length difference of USB 2.0 differential data traces is less than 0.7 mm.
Table 12: USB Trace Length Inside the Module
Pin
Signal
Length (mm)
Length Difference (DP - DM)
13
USB_DM
14.94
0.48
14
USB_DP
15.42
173
HUB_USB_DP
17.66
-0.12
174
HUB_USB_DM
17.78