TOBY-L4 series - System Integration Manual
UBX-16024839 - R04
Design-in
Page 91 of 143
Ring Indicator
If a 1.8 V external Processor / Device is used, the Ring Indicator circuit should be implemented as illustrated in
Figure 50.
1.8V Processor / Device
RI
GND
TOBY-L4 series
11
RI
GND
Figure 50: 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 appropriate unidirectional voltage translators using the module
V_INT
output as a
1.8 V supply for the voltage translator on the module side, as illustrated in Figure 51.
5
V_INT
RI
3V Processor / Device
GND
TOBY-L4 series
11
RI
GND
1V8
B1
A1
GND
U1
VCCB
VCCA
Unidirectional
Voltage Translator
C1
C2
3V0
DIR2
OE
VCC
B2
A2
TP
DIR1
Figure 51: Ring Indicator application circuit to connect an external 3.0V 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
18
- Texas Instruments
Table 37: Component for the Ring Indicator application circuit to connect an external 3.0V processor / device
18
Voltage translator providing partial power down feature so that the external 3.0 V supply can be ramped up before the
V_INT
1.8 V supply