Product Info

LTE Standard Module Series
EC21_Series_Hardware_Design
30
/ 118
V
OH
min = 2.55 V
USIM_CLK 16 DO (U)SIM card clock
1.8 V (U)SIM
：
V
OL
max = 0.45 V
V
OH
min = 1.35 V
3.0 V (U)SIM
：
V
OL
max = 0.45 V
V
OH
min = 2.55 V
USIM_RST 17 DO (U)SIM card reset
1.8 V (U)SIM
：
V
OL
max = 0.45 V
V
OH
min = 1.35 V
3.0 V (U)SIM
：
V
OL
max = 0.45 V
V
OH
min = 2.55 V
Main UART Interface
Pin Name Pin No. I/O Description
DC
Characteristics
Comment
RI 62 DO Ring indication
V
OL
max = 0.45 V
V
OH
min = 1.35 V
1.8 V power domain.
If unused, keep them
open.
DCD 63 DO Data carrier detect
CTS 64 DO
DTE clear to send
signal from DCE
RTS 65 DI
DTE request to
send signal from
DCE
V
IL
min = -0.3 V
V
IL
max = 0.6 V
V
IH
min = 1.2 V
V
IH
max = 2.0 V
1.8 V power domain.
If unused, keep it
open.
DTR 66 DI
DTE Data terminal
ready, sleep mode
control
V
IL
min = -0.3 V
V
IL
max = 0.6 V
V
IH
min = 1.2 V
V
IH
max = 2.0 V
1.8 V power domain.
Pulled up by default.
Low level can wake up
the module.
If unused, keep it
open.
TXD 67 DO Transmit
V
OL
max = 0.45 V
V
OH
min = 1.35 V
1.8 V power domain.
If unused, keep it
open.
RXD 68 DI Receive
V
IL
min = -0.3 V
V
IL
max = 0.6 V
V
IH
min = 1.2 V
V
IH
max = 2.0 V
1.8 V power domain.
If unused, keep it
open.
Debug UART Interface