Integration Manual

Table Of Contents
TOBY-L3 series - System Integration Manual
TSD-19090601 - R13 System Integration Manual Page 101 of 143
5
V_INT
RI
3V Processor / Device
GND
TOBY-L3 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 48: Ring Indicator(Configured by GPIO8) 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
9
- Texas Instruments
Table 37: Component for the Ring Indicator application circuit to connect an external 3.0V processor / device
Do not apply voltage to any UART interfaces pin before the switch-on of the UART supply source
(V_INT), to avoid latch-up of circuits and allow a clean boot of the module.
The ESD sensitivity rating of UART pins is 1 kV (HBM according to JESD22-A114). A higher protection
level could be required if the lines are externally accessible and it can be achieved by mounting an ESD
protection (e.g. EPCOS CA05P4S14THSG) close to the accessible points.
If the UART interfaces pins are not used, they can be left unconnected on the application board, but it
is recommended to provide accessible test points directly connected to the UART0 TXD and RXD pins
for diagnostic purposes.
2.6.2.2 Guidelines for UART layout design
The UART serial interface requires the same considerations regarding electro-magnetic interference as any
other digital interface. Keep the traces short and avoid coupling with RF line or sensitive analog inputs,
since the signals can cause the radiation of some harmonics of the digital data frequency.
2.6.3 SPI interfaces
SPI interfaces are not supported by the "0x" product feature versions.
2.6.3.1 Guidelines for SPI circuit design
TOBY-L3 series modules include up to two 1.8 V Serial Peripheral Interfaces to communicate with external
SPI slave devices, with the module acting as SPI master, by means of the open CPU API.
9
Voltage translator providing partial power down feature: the external 3.0 V supply can be ramped up before V_INT 1.8 V supply