SPRUI30H November 2015 – May 2024 DRA745 , DRA746 , DRA750 , DRA756
Figure 26-5 is a simplified block diagram of the DPLL_SATA instance integration in the SATA clock generator subsystem.
The input clock CLKINP goes to a predivider N + 1. The entire loop runs on the REFCLK clock after this predivider. The value of N + 1 is controlled through the DPLLCTRL_SATA.PLL_CONFIGURATION1[8:1] PLL_REGN bit field.
The frequency ranges for the DPLL_SATA input clock (CLKINP) and the DPLL internal reference clock (REFCLK = CLKINP/N + 1) are:
The output clock CLKDCOLDO is synthesized by digitally controlled oscillator (the DCO block), that automatically detects the frequency range. The CLKDCOLDO frequency can be given with CLKDCOLDO = CLKINP × M/(N + 1). For that purpose the feedback multiplier M must be configured through the DPLLCTRL_SATA.PLL_CONFIGURATION1[20:9] PLL_REGM bit field.
The DPLL_SATA module supports fractional synthesis (that is, the frequency multiplication factor M can be programmed as fractional). This is achieved by having a sigma delta feedback divider (M). A fractional value (Fractional M) of 18 bits is supported enabling control for a better accuracy. Programming the 18-bit Fractional M value is done by setting the DPLLCTRL_SATA.PLL_CONFIGURATION4[17:0] PLL_REGM_F bit field (similar to REGM). To enable integer only division Fractional M should be set to 000…0.
Fractional synthesis is not supported for M > 4093.