LPWA Module Series
BG770A-GL Hardware Design
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The following figures illustrate reference designs of USB PHY and USB interface.
VI N
EN
VO UT
GND
VBAT
1uF
C1
R1
R2
0R
10K
VDD_EXT
USBPHY_3P3_EN
1uF
C2
USBPHY_3P3
U1
SG M2040-3.3
Figure 15: Reference Design of USB PHY
Figure 16: Reference Design of USB Interface
To ensure the integrity of USB data trace 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.
To meet USB 2.0 specification, comply with the following principles while designing the USB interface.
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.
Junction capacitance of the ESD protection device might cause influences on USB data lines, so pay
