Quectel BC66 - UART Interfaces

NB-IoT Module Series
BC66&BC660K-GL Compatible Design
BC66&BC660K-GL_Compatible_Design 23 / 30
4.8. UART Interfaces
The UART interfaces of BC66/BC660K-GL have different voltage domains, as listed below.
Table 8: UART Interface Voltage Domain
A compatible voltage level translation reference design for BC66/BC660K-GL’s UART interfaces is shown
below. For designs of the circuits in dotted lines, refer to those in solid lines, and pay attention to the
direction of connection.
DTE
VDD_EXT
10 kΩ
VCC_DTE
4.7 kΩ
VDD_EXT
BC66/BC660K-GL
1 nF
RXD
TXD
DBG_TXD
DBG_RXD
TXD_AUX
RXD_AUX
GPIO
GND
GND
DBG_RXD
DBG_TXD
RI
MAIN_TXD
MAIN_RXD
RI
DBG_TXD
TXD
RXD
DBG_RXD
RXD_AUX
TXD_AUX
VIO_SEL
NM_0 Ω
R1
D1
R2
10 kΩ
Figure 13: Compatible Reference Design for Level Conversion Circuits
Module
UART Interface
Voltage Domain
BC66
Main UART
1.8 V
Debug UART
AUX UART
BC660K-GL
Main UART
1.8/3.3 V
Debug UART