NINA-B4 series - System integration manual
UBX-19052230 - R06
Functional description
Page 14 of 45
C1-Public
1.9.1
External crystal
NINA-B4 modules have two input pins for connecting an external low-frequency crystal (LXFO) as
source for the low power clock. This setup enables NINA-B4 modules to run with the lowest overall
power consumption.
Table 3 describes the details of the crystal used on EVK-NINA-B4.
Table 7: Components used on the NINA-B4 EVK evaluation kit
☞
The specifications for external LFXO sources are described in the electrical specifications of the
respective data sheet [2][3].
1.9.2
Internal oscillator
Choosing to use NINA-B4 modules with the internal oscillator makes for a leaner BOM reduces the
cost to end users. This choice of oscillator adversely provides slightly higher sleep mode power
consumption.
When using the internal oscillator, pins XL1 and XL2 must be connected to ground. In NINA-B40 these
pins can be reassigned and used for GPIO
.
⚠
To ensure that the clock is stable at +/- 250ppm, the customer application software must check
the calibration of the internal oscillator at least once every 8 seconds.
1.9.3
External clock source
As an alternative to using an external crystal, an external clock source generated from a host CPU or
a TCXO can be used. The clock source can be either a low-swing or full-swing signal.
The electrical parameters are stated in the respective product data sheets [2] and [3].
Pin name
Parameter
Min
Typ
Max
Unit
Remarks
XL1
Input characteristic:
Peak to Peak amplitude
200
1000
mV
Input signal must not swing outside
supply rails.
XL2
-
-
-
-
Connect to GND
Table 8: Electrical parameters for a low-swing clock
Pin name
Parameter
Min
Typ
Max
Unit
Remarks
XL1
Input characteristic:
Low-level input
0
0.3*VCC
V
Input characteristic:
high-level input
0.7*VCC
VCC
V
XL2
-
-
-
-
-
Connect to GND
Table 9: Electrical parameters for a full-swing clock
Component
Value
Note
Crystal oscillator
32.768 kHz – 20 ppm
EPSON FC-12M used on NINA-B4 EVK
