CC3100_15 datasheet(17/44 Pages) TI

17 / 44 page

SWAS031-029

RTC_XTAL_P

RTC_XTAL_N

Host system

32.768 kHz

VIO

100 K

RTC_XTAL_P

RTC_XTAL_N

32.768 kHz

10 pF

GND

10 pF

SWAS031-028

CC3100

www.ti.com

SWAS031D – JUNE 2013 – REVISED FEBRUARY 2015

4.11.3.1 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.

Figure 4-9 shows the crystal connections for the slow clock.

Figure 4-9. RTC Crystal Connections

4.11.3.2 Slow Clock Using an External Clock

When an RTC clock oscillator is present in the system, the CC3100 device can accept this clock directly as an

input. The clock is fed on the RTC_XTAL_P line and the RTC_XTAL_N line is held to VIO. The clock must be a

CMOS-level clock compatible with VIO fed to the device.

Figure 4-10 shows the external RTC clock input connection.

Figure 4-10. External RTC Clock Input

4.11.3.3 Fast Clock (Fref) Using an External Crystal

The CC3100 device also incorporates an internal crystal oscillator to support a crystal-based fast clock. The

XTAL is fed directly between WLAN_XTAL_P (pin 23) and WLAN_XTAL_N (pin 22) with suitable loading

capacitors.

Figure 4-11 shows the crystal connections for the fast clock.

Specifications

Submit Documentation Feedback

Product Folder Links: CC3100

CC3100 Datasheet(PDF) 17 Page - Texas Instruments