Quectel SC66 Hardware Design page 60

DEBUG_RXD 6
UART1_TXD 7
UART1_RXD 8
UART6_RXD 198
UART6_TXD 199
UART6_CTS 246
UART6_RTS 245
LPI_UART_2_
60
TXD
LPI_UART_2_
61
RXD
UART6 is a 4-wire UART interface with 1.8V power domain. A level translator chip should be used if
customers' application is equipped with a 3.3V UART interface. A level translator chip TXS0104EPWR
provided by Texas Instruments is recommended.
The following figure shows a reference design.
LDO11A_1P8
C1
100 pF
UART 6_ CTS
UART 6_ RTS
UART6_ TXD
UART6_ RXD
Figure 17: Reference Circuit with Level Translator Chip (for UART6)
The following figure is an example of connection between SC66 and PC. A voltage level translator and a
RS-232 level translator chip are recommended to be added between the module and PC, as shown
below:
SC66_Hardware_Design
data
DEBUG UART receive
DI
data
DO UART1 transmit data
DI UART1 receive data
DI UART6 receive data
DO UART6 transmit data
DI UART6 clear to send
DO UART6 request to send
LPI_UART_2
DO
transmit data
LPI_UART_2
DI
receive data
VCCB
VCCA
U1
OE
GND
A1 B1
A2 B2
TXS0104EPWR
A3 B3
A4 B4
Smart LTE Module Series
SC66 Hardware Design
1.8 power domain.
1.8 power domain.
1.8 power domain.
1.8 power domain.
1.8 power domain.
1.8 power domain.
1.8 power domain.
1.8 power domain.
Cannot be multiplexed into
general-purpose GPIOs..
VDD_3.3V
C2
100pF
CTS_3.3V
RTS_3.3V
TXD_3.3V
RXD_3.3V
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