Product Info

LPWA Module Series
BG600L-M3 Hardware Design
BG600L-M3_Hardware_Design 42 / 83
The USB interface is recommended to be reserved for firmware upgrade or debugging in application
designs. The following figures illustrate reference designs of USB PHY and USB interface.
VIN
EN
VOUT
GND
VBAT
1 μF
C1
R1
R2
0R
10K
VDD_EXT
USBPHY_3P3_EN
1 μF
C2
USBPHY_3P3
U1
SGM2040-3.3
Figure 16: Reference Design of USB PHY
Figure 17: Reference Circuit of USB Interface
In order to ensure the integrity of USB data line signal, components R3 and R4 should be placed close to
the module, and also these resistors should be placed close to each other. The extra stubs of trace must
be as short as possible.
The following principles should be complied with while designing the USB interface, so as to meet USB
2.0 specification.
 It is important to route the USB signal traces as differential pairs with ground surrounded. The
impedance of USB differential trace is 90 Ω.
 Do not route signal traces under crystals, oscillators, magnetic devices and RF signal traces. It is
important to route the USB differential traces in inner-layer of the PCB, and surround the traces with
ground on that layer and with ground planes above and below.