vivado报错：[DRC PDRC-34] MMCM_adv_ClkFrequency_div_no_dclk

我在vivado2018.3使用了一个MMCM作为我的锁相环输入频率为50MHZ我设置了双输出时钟一个输出clk频率25.175MHZ另一个输出clk为125.875MHZ也就是第一个clk的五倍时钟输出。但是在综合时报错[DRC PDRC-34] MMCM_adv_ClkFrequency_div_no_dclk: The computed value 2000.000 MHz (CLKIN1_PERIOD, net clk_in1_clk_wiz_0) for the VCO operating frequency of the MMCME2_ADV site MMCME2_ADV_X1Y1 (cell pll_clk_inst/clk_wiz_0_inst/inst/mmcm_adv_inst) falls outside the operating range of the MMCM VCO frequency for this device (600.000 - 1440.000 MHz). The computed value is (CLKFBOUT_MULT_F * 1000 / (CLKINx_PERIOD * DIVCLK_DIVIDE)). Please run update_timing to update the MMCM settings. If that does not work, adjust either the input period CLKINx_PERIOD (20.000000), multiplication factor CLKFBOUT_MULT_F (40.000000) or the division factor DIVCLK_DIVIDE (1), in order to achieve a VCO frequency within the rated operating range for this device.翻译一下大致就是说MMCM的VCO压控振荡器工作频率为600—1440MHZ现在我的VCO为2000MHZ超过了这个频率。然后给了一个公式然后说我现在的CLKFBOUT_MULT_F是40CLKINx_PERIOD是20 DIVCLK_DIVIDE是1所以VCO是40×1000/20×1 2000MHZ超过了VCO的频率上限。为什么CLKFBOUT_MULT_F跳到了40是为了匹配两个输出clk25.175向上乘到整数刚好是4040×25.175 1007这里我对CLKFBOUT_MULT_F的自动取值并不是很了解。解决办法是我将输出clk的时钟精度砍到了25MHZ和125MHZMMCM就可以正常运行了。