CC3220 Datasheet, PDF (37/84 Pages) Texas Instruments – SimpleLink Wi-Fi Wireless and Internet-of-Things Solution, a Single-Chip Wireless MCU

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CC3220
SWAS035A – SEPTEMBER 2016 – REVISED FEBRUARY 2017
4.14.3.3 Wakeup From HIBERNATE Mode
Figure 4-8 shows the timing diagram for wakeup from HIBERNATE mode.
Application software requests
entry to HIBERNATE mode
T_{HIB_MIN}
T2
T3
VBAT
VIO
nRESET
STATE ACTIVE
HIBERNATE HW WAKEUP
FW INIT
T4
APP CODE
LOAD
EXECUTION
32-kHz
RTC CLK
Figure 4-8. Wakeup From HIBERNATE Timing Diagram
NOTE
The 32.768-kHz XTAL is kept enabled by default when the chip goes into HIBERNATE
mode.
describes the software hibernate timing requirements.
4.14.4 Clock Specifications
The CC3220x device requires two separate clocks for its operation:
• A slow clock running at 32.768 kHz is used for the RTC.
• A fast clock running at 40 MHz is used by the device for the internal processor and the WLAN
subsystem.
The device features internal oscillators that enable the use of less-expensive crystals rather than
dedicated TCXOs for these clocks. The RTC can also be fed externally to provide reuse of an existing
clock on the system and to reduce overall cost.
4.14.4.1 Slow Clock Using Internal Oscillator
The RTC crystal connected on the device supplies the free-running slow clock. The accuracy of the slow
clock frequency must be 32.768 kHz ±150 ppm. In this mode of operation, the crystal is tied between
RTC_XTAL_P (pin 51) and RTC_XTAL_N (pin 52) with a suitable load capacitance to meet the ppm
requirement.
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