Integration Manual

TSD-19090601 - R15 Contents Page 60 of 143
9. Other digital interfaces: (UART, SPI, I
2
C, I
2
S, Host Select, GPIOs, and Reserved pins).
Accurate design is required to guarantee correct functionality and reduce the risk of digital data
frequency harmonics coupling. Follow the suggestions provided in sections 2.6.1, 2.6.3, 2.6.4, 2.3.3, 2.10,
2.11.
10. Other supplies: V_INT is generic digital interface supply.
Correct design is required to guarantee functionality. Follow the suggestions provided in 2.2.2.
☞ It is recommended to also follow the specific design guidelines provided by each manufacturer of any
external part selected for the application board that integrates the u-blox cellular modules.
2.2 Supply interfaces
2.2.1 Module supply (VCC)
2.2.1.1 General guidelines for VCC supply circuit selection and design
All the available VCC pins must be connected to the external supply minimizing the power loss due to
series resistance.
GND pins are internally connected. Application design shall connect all the available pads to solid ground
on the application board, since a good (low impedance) connection to external ground can minimize power
loss and improve RF and thermal performance.
TOBY-L3 series modules must be sourced through the VCC pins with a suitable DC power supply that
should meet the following prerequisites to comply with the modules’ VCC requirements summarized in
Table 7.
The suitable DC power supply can be selected according to the application requirements (see Figure 10)
between the different possible supply sources types, which most common ones are the following:
 Switching DC/DC regulator
 Low Drop-Out (LDO) linear regulator
 Rechargeable Lithium-ion (Li-Ion) or Lithium-ion polymer (Li-Pol) battery
 Primary (disposable) battery