NINA-B3 series - System integration manual 
UBX-17056748 - R13  System description  Page 10 of 72 
C1-Public 
DC/DC efficiency should be evaluated as a tradeoff between active and idle duty cycles of the specific 
application.  Although  some  DC/DC  can  achieve  high  efficiency  at  extremely  light  loads,  a  typical 
DC/DC efficiency quickly degrades as idle current drops below a few mA, greatly reducing the battery 
life. 
Due to the low current consumption and wide voltage range of the NINA-B3 series module, a battery 
can be used as a main supply. The capacity of the battery should be selected to match the application. 
Care should be taken so that the battery can deliver the peak current required by the module. See the 
NINA-B3 series data sheet [2] for the electrical specifications.  
It is best practice to include  decoupling capacitors on the supply rails close to the  NINA-B3 series 
module. But depending on the design of the power routing on the host system, capacitance might not 
be needed. 
1.5  System function interfaces  
1.5.1  Module reset 
You can reset NINA-B3 modules by applying a low level on the RESET_N input pin, which is normally 
set high with an internal pull-up. This causes an “external” or “hardware” reset of the module. The 
current  parameter  settings are  not  saved  in  the  non-volatile  memory  of  the  module  and a  proper 
network detach is not performed. 
1.5.2  Internal temperature sensor 
The  radio  chip  in  NINA-B3  contains  a  temperature  sensor  used  for  over  temperature  and  under 
temperature shutdown.  
⚠  The temperature sensor is  located  inside the radio chip and should not be used if an accurate 
temperature reading of the surrounding environment is required.  
1.6  Debug – Serial Wire Debug (SWD) 
The primary interface for debugging is the SWD interface. NINA-B30 series modules provide an SWD 
interface for flashing and debugging. The two pins SWDIO and SWDCLK should be made accessible 
on header or test points.  
The SWD interface is disabled on the NINA-B31 series modules. 
1.7  Serial interfaces 
⚠  As NINA B3 can be used with both the u-connectXpress and open CPU based applications, based 
on  the  Nordic  SDK,  the  available  interfaces  and  the  pin  mapping  may  vary.  For  detailed  pin 
information, see Pin configuration and function.  
1.7.1  Universal Asynchronous Serial Interface (UART) 
NINA B3 provides a Universal Asynchronous Serial Interface (UART) for data communication.  
The following UART signals are available:   
•  Data lines (RXD as input, TXD as output)  
•  Hardware flow control lines (CTS as input, RTS as output)   
•  DSR and DTS are used to set and indicate system modes