TOBY-L2 and MPCI-L2 series - System Integration Manual
UBX-13004618 - R28
Design-in
Page 132 of 164
2.17
Design-in checklist
This section provides a design-in checklist.
2.17.1
Schematic checklist
The following are the most important points for a simple schematic check:
DC supply must provide a nominal voltage at VCC / 3.3Vaux pin within the operating range
limits.
DC supply must be capable of supporting both the highest peak and the highest averaged
current consumption values in connected-mode, as specified in the TOBY-L2 series Data
or in the MPCI-L2 series Data Sheet
VCC / 3.3Vaux 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.
Check USB_D+ / USB_D- signal lines as well as very low capacitance ESD protections if
accessible.
Capacitance and series resistance must be limited on each SIM signal to match the SIM
specifications.
Insert the suggested capacitors on each SIM signal and low capacitance ESD protections if
accessible.
Check UART signals direction, as the TOBY-L2 signal names follow the ITU-T V.24
Recommendation
Consider providing appropriate low value series damping resistors on SDIO lines to avoid
reflections.
Add a proper pull-up resistor (e.g. 4.7 k
) to V_INT or another proper 1.8 V supply on each DDC
(I
2
C) interface line, if the interface is used.
Check the digital audio interface specifications to connect a proper external audio device.
Consider passive filtering parts on each used analog audio line.
Provide accessible test points directly connected to the following pins of the TOBY-L2 series
modules: V_INT, PWR_ON and RESET_N for diagnostic purpose.
Provide accessible test points directly connected to all the UART pins of the TOBY-L2 series
modules (TXD, RXD, RTS, CTS, DTR, DSR, DCD, RI) for diagnostic purpose, in particular
providing a 0
series jumper on each line to detach each UART pin of the module from the DTE
application processor.
If the USB is not used, provide accessible test points directly connected to the USB_D+ and
USB_D- pins
Provide proper precautions for EMC / ESD immunity as required on the application board.
Do not apply voltage to any generic digital interface pin of TOBY-L2 series modules before the
switch-on of the generic digital interface supply source (V_INT).
All unused pins can be left unconnected except the RSVD pin number 6 of TOBY-L2 series
modules, which must be connected to GND.