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arria 10 fpll can not work nomally


Hi sir,

      I am facing one strange problem, details as follows:

      1. when I use gxp_dedicated_clock for the reference clock of the transceiver fpll, after power-on, cal_busy signal is low, but the locked signal is not asserted infinitly, I am sure the clock is clean and stable; (Transceive in cascading mode, and the problem at the upstream fpll, i think the problem exists at the downstream fpll yet).

         Note: when power-on, the reference clock is not my need, firstly, I adjust the clock of the reference clock, then I asserted pll_powedown long time, and the fpll can not work normally;

     2. Based 1, I make the fpll work under core mode, and provide the same reference clock, and do the same thing as 1's note, and the fpll can not work normally. When I asserted the pll_powerdown, the fpll can not lock and output the error frequency.

     3. after 2, I change the reference clock to lvds io(clk pins), and do the same thing as 2, when I power on, I found the fpll can output correct frequency, and fpll can lock; but when I assert the pll_powerdown and not release, I find the fpll can output  correct frequency, and fpll locks stilly;  That means, pll can work at reset state, and pll_powerdown has no effect.

     soft:: quartus 16.0

      develope board: a10gx_si_e4 (10gx115s2f45i1sg)


                  altclk_ctrl inst_0(.inclk(clk_i), outclk(ref_clk));

                  fpll_test   fpll_test_inst(.outclk0 (outclk), .pll_cal_busy(cal_busy), .pll_locked(clk_locked),pll_powerdown(pll_powerdown), .pll_refclk0(ref_clk));

       Could some help me about this problem, thanks.



Best regards,



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