ANNA-B112 - System integration manual
UBX-18009821 - R09
System description
Page 11 of 66
C1-Public
Figure 2: Connecting ANNA-B112 to an external crystal oscillator
Table 3: Components used on the EVK-ANNA-B112 EVK evaluation kit
1.6.2
Internal oscillator
Using ANNA-B112 with the internal oscillator will enable a minimal BOM, saving cost for the end
product. This will however increase the power consumption during sleep.
When using the internal oscillator, the clock pins (pin 17 and pin 18) should be connected to ground.
⚠
The application must ensure calibration of the internal oscillator at least once every 8 seconds to
/-250ppm clock stability.
1.6.3
External clock source
An external clock source generated from for example a host CPU can also be used. The clock source
can be either low swing signal or full swing signal.
The electrical parameters are stated in Table 4 and Table 5.
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 4: 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 or leave unconnected
Table 5: Electrical parameters for a full swing clock
Component
Value
Note
Crystal oscillator
32.768 kHz – 20 ppm
EPSON FC-12M used on ANNA-B112 EVK
Capacitors
22pF
