STM32W108B-SK STMicroelectronics, STM32W108B-SK Datasheet - Page 11

• Manufacturer Part Number: STM32W108B-SK
• Description: STARTER KIT FOR STM32W108
• Manufacturer: STMicroelectronics
• Series: STM32r
• Type: MCUr

Specifications of STM32W108B-SK

• Featured Product: STM32 Cortex-M3 Companion Products
• Contents: Board
• Silicon Manufacturer: ST Micro
• Core Architecture: ARM
• Core Sub-architecture: Cortex - M3
• Silicon Core Number: STM32
• Silicon Family Name: STM32W108xx
• Kit Contents: Board
• Features: IEEE
• Mfg Application Notes: STM32W108 Adjacent Channel Rejection Measurements
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With/related Products: *
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

AN3206
3.2
Table 2.
Optional Low-frequency crystal reference (X2, C27 and C26)
The STM32W contains an integrated sleep timer that allows for software configuration of
sleep/wake cycles of the wireless node. There are two options for driving the sleep timer: a
32.768 kHz crystal oscillator or an internal RC oscillator. The crystal oscillator is more
accurate but consumes more current than the RC oscillator. The RC oscillator is sufficient
for operating ST's IEEE 802.15.4 software libraries and stacks. Therefore, the application's
sleep timing accuracy will decide if a 32-kHz crystal is required.
Figure 7
overdriving the oscillator circuit within the STM32W, ST recommends an asymmetrical
loading of the crystal.
Figure 7.
If the application does not need the 32-kHz crystal, then the pins OSC32A (GPIO22) and
OSC32B (GPIO23) can be used as a general-purpose IO.
Frequency
Duty cycle
Phase noise from 1kHz to
100kHz
Accuracy
Crystal ESR
Crystal ESR
Start-up time to stable clock
(max. bias)
Start-up time to stable clock
(optimum bias)
Parameter
illustrates the crystal oscillator with its loading capacitors. To reduce the effects of
High frequency crystal requirements
32-kHz low-frequency crystal
Initial, temperature, and
aging
Load capacitance of 10pF
Load capacitance of 18pF
Doc ID 17406 Rev 3
Test Conditions
Min.
- 40
Non-RF design considerations
40
Typ.
24
Max.
- 120
+ 40
100
60
60
1
2
dBc/Hz
Unit
MHz
ppm
ms
ms
%
11/14