@classmethod
def get_pll_mhz(mcs, pll_reg):
    """The getter method for PLL output clocks.

        Parameters
        ----------
        pll_reg : Register
            The control register for a PLL

        Returns
        -------
        float
            The PLL output clock rate measured in MHz.

        """
    if pll_reg[mcs.CRX_APB_SRC_FIELD] != mcs.CRX_APB_SRC_DEFAULT:
        raise ValueError('Invalid PLL Source')
    pll_fbdiv = pll_reg[mcs.CRX_APB_FBDIV_FIELD]
    if pll_reg[mcs.CRX_APB_ODIVBY2_FIELD] == 1:
        pll_odiv2 = 2
    else:
        pll_odiv2 = 1
    return mcs.DEFAULT_SRC_CLK_MHZ * pll_fbdiv / pll_odiv2
