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CC3135 Datasheet(PDF) 32 Page - Texas Instruments |
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CC3135 Datasheet(HTML) 32 Page - Texas Instruments |
32 / 78 page ![]() RTC_XTAL_P RTC_XTAL_N 51 52 32.768 kHz 10 pF GND GND 10 pF Copyright © 2017, Texas Instruments Incorporated 32 CC3135 SWAS037 – JANUARY 2019 www.ti.com Submit Documentation Feedback Product Folder Links: CC3135 Specifications Copyright © 2019, Texas Instruments Incorporated 5.17.5 Clock Specifications The CC3135 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. 5.17.5.1 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. Figure 5-9 shows the crystal connections for the slow clock. Figure 5-9. RTC Crystal Connections Table 5-14 lists the RTC crystal requirements. Table 5-14. RTC Crystal Requirements CHARACTERISTICS TEST CONDITIONS MIN TYP MAX UNIT Frequency 32.768 kHz Frequency accuracy Initial plus temperature plus aging ±150 ppm Crystal ESR 32.768 kHz 70 kΩ |
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