SARA-R4/N4 series - System Integration Manual
UBX-16029218 - R11
Design-in
Page 118 of 157
2.14
Design-in checklist
This section provides a design-in checklist.
2.14.1
Schematic checklist
The following are the most important points for a simple schematic check:
DC supply must provide a nominal voltage at
VCC
pin within the operating range limits.
DC supply must be capable of supporting the highest peak / pulse current consumption values and
the maximum averaged current consumption values in connected mode, as specified in the SARA-
R4/N4 series Data Sheet
VCC
voltage supply should be clean, with very low ripple/noise: provide the suggested bypass
capacitors, in particular if the application device integrates an internal antenna.
Do not apply loads which might exceed the limit for maximum available current from
V_INT
supply.
Check that voltage level of any connected pin does not exceed the relative operating range.
Provide accessible test points directly connected to the following pins of the SARA-R4/N4 series
modules:
V_INT
,
PWR_ON
and
RESET_N
for diagnostic purposes.
Capacitance and series resistance must be limited on each SIM signal to match the SIM
specifications.
Insert the suggested pF capacitors on each SIM signal and low capacitance ESD protections if
accessible.
Check UART signals direction, as the modules’ signal names follow the ITU-T V.24 Recommendation
Capacitance and series resistance must be limited on each high speed line of the USB interface.
It is strongly recommended to provide accessible test points directly connected to the USB interface
pins (
VUSB_DET
,
USB_D+
and
USB_D-
pins).
Use transistors with at least an integrated resistor in the base pin or otherwise put a 10 k
resistor
on the board in series to the GPIO when those are used to drive LEDs.
Provide adequate precautions for EMC / ESD immunity as required on the application board.
Do not apply voltage to any generic digital interface pin of SARA-R4/N4 series modules before the
switch-on of the generic digital interface supply source (
V_INT
).
All unused pins can be left unconnected.
2.14.2
Layout checklist
The following are the most important points for a simple layout check:
