SARA-R4/N4 series - System Integration Manual
UBX-16029218 - R11
Design-in
Page 103 of 157
4
V_INT
TxD
Applicat ion Processor
(3.0 V DTE)
RxD
DTR
DSR
RI
DCD
GND
SARA-R4/ N4
(1.8 V DCE)
12
TXD
9
DTR
13
RXD
6
DSR
7
RI
8
DCD
GND
1V8
B1
A1
GND
U1
VCCB
VCCA
Unidirect ional
Volt age Translat or
C1
C2
3V0
DIR1
DIR2
OE
VCC
B2
A2
RTS
CTS
10
RTS
11
CTS
TP
0
Ω
TP
0
Ω
TP
0
Ω
TP
TP
Figure 47: UART interface application circuit with a partial V.24 link (3-wire) in DTE/DCE serial communication (3.0 V DTE)
Reference
Description
Part Number - Manufacturer
C1, C2
100 nF Capacitor Ceramic X7R 0402 10% 16 V
GRM155R61A104KA01 - Murata
U1
Unidirectional Voltage Translator
SN74AVC2T245
19
- Texas Instruments
Table 32: UART application circuit components with partial V.24 link (3-wire) in DTE/DCE serial communication (3.0 V DTE)
19
Voltage translator providing partial power down feature so that the DTE 3 V supply can be also ramped up before
V_INT
1.8 V supply