LPWA Module Series
BG77 Hardware Design
BG77_Hardware_Design 38 / 76
For more details about USB 2.0 specification, please visit http://www.usb.org/home.
The USB interface is recommended to be reserved for firmware upgrade in customers’ design. The
following figures illustrate reference designs of USB PHY and USB interface.
VIN
EN
VOUT
GND
VBAT
1uF
C1
R1
R2
0R
10K
VDD_EXT
EXT_PWR_EN
1uF
C2
VDD_USB_3V3
U1
SGM2040-3.3
Figure 15: Reference Design of USB PHY
USB_DP
USB_DM
GND
USB_DP
USB_DM
GND
L1
Close to Module
R1
R2
Test Points
ESD Array
NM_0R
NM_0R
Minimize these stubs
Module
MCU
USB_VBUS
VDD (
1.3~1.8V
)
USB_VDDA_3P3
LDO
3.3V
VBAT
EN
OUT
IN
GND
EXT_PWR_EN
VDD_EXT
10K
R3
Figure 16: Reference Design of USB Interface
USB_VDDA_3P3 42
PI
Power supply for USB PHY
circuit
Vnorm=3.3V
EXT_PWR_EN
64 DO
External LDO enable of USB
1.8V power domain
GND 43
Ground