SWRU543B January 2019 – June 2025 CC3230S , CC3230SF , CC3235MODS , CC3235MODSF , CC3235S , CC3235SF
Pin 45 and pin 52 are used by an internal DC/DC (ANA2_DCDC) and the RTC crystal oscillator, respectively. These modules use automatic configuration sensing. Thus, some board-level configuration is required to use pin 45 and pin 52 as digital pads. Figure 16-2 shows this board-level configuration.
In a CC32xxR device, ANA2 DC/DC is not required, which allows use of pins for digital functions. However, pin 47 must be shorted to the supply input.
Typically, pin 52 is used up for RTC crystal in most applications. In some applications, however, a 32.768-kHz square-wave clock may be available onboard. In such cases, the crystal may be removed, freeing up pin 52 for digital functions. The external clock must then be applied at pin 51. For the chip to automatically detect this configuration, a 100K pullup resistor must be connected between pin 52 and the supply line. To prevent false detection, TI recommends using pin 52 for output-only functionalities.