Integration Manual

Table Of Contents
TOBY-L3 series - System Integration Manual
TSD-19090601 - R13 System Integration Manual Page 100 of 143
5
V_INT
TxD
3V Processor / Device
RxD
GND
TOBY-L3 series
TXDx
RXDx
GND
1V8
B1 A1
GND
U1
VCCB
VCCA
Unidirectional
Voltage Translator
C1 C2
3V0
DIR1
DIR2
OE
VCC
B2 A2
TP
0 Ohm
TP
0 Ohm
TP
Figure 46: 2-wire UART interface application circuit to connect an external 3.0 V processor / device
Reference
Description
Part Number - Manufacturer
C1, C2
100 nF Capacitor Ceramic X7R 0402 10% 16 V
GRM155R61A104KA01 - Murata
U1
Unidirectional Voltage Translator
SN74AVC2T245
8
- Texas Instruments
Table 36: Component for 2-wire UART interface application circuit to connect an external 3.0 V processor / device
Test-Points for diagnostic access are recommended to be provided on the UART0 TXD and RXD lines
for diagnostic purposes. Test-Points are not required on other UART lines.
Ring Indicator
If a 1.8 V external Processor / Device is used, the Ring Indicator circuit should be implemented as shown
in Figure 47.
1.8V Processor / Device
RI
GND
TOBY-L3 series
11
RI
GND
Figure 47: Ring Indicator application circuit to connect an external 1.8V processor / device
If a 3.0 V external Processor / Device is used, then it is recommended to connect the 1.8 V Ring Indicator
output of the module by means of proper unidirectional voltage translators using the module V_INT output
as a 1.8 V supply for the voltage translator on the module side, as shown in Figure 48.
8
Voltage translator providing partial power down feature, thus the external 3.0 V rail can be ramped up before V_INT 1.8 V rail