SPRUIE9D May 2017 – May 2024 DRA74P , DRA75P , DRA76P , DRA77P
VIDEO1 PLL use type-A instances of the DPLL modules. For information regarding DPLL types, see Power, Reset, and Clock Management.
Figure 13-10 shows the internal reference diagram of a single VIDEO PLL.
Figure 13-10 VIDEO PLL Reference DiagramReference clock control is enabled with PLL_CONFIGURATION2[13] PLL_REFEN bit.
Figure 13-11 is a simplified block diagram of the DPLL_VIDEO instance used for pixel clock generation.
Figure 13-11 DPLL_VIDEO Functional Block DiagramThe input clock CLKINP goes to a pre-divider N + 1.The entire loop runs on the REFCLK clock after this pre-divider. The value of N + 1 is controlled through the PLL_CONFIGURATION1[8:1] PLL_REGN bit field. The CLKINP range is 0.032MHz to 52MHz. The REFCLK range is 0.15MHz to 52MHz.
The output clock DCOCLK is synthesized by a digitally controlled oscillator (the DCO block) that automatically detects the frequency range. The DCOCLK frequency can be given with DCOCLK = CLKINP × 2 × M / (N + 1). For that purpose the feedback multiplier M must be configured through the PLL_CONFIGURATION1[20:9] PLL_REGM bit field.
The CLKOUT frequency can be given with CLKOUT = DCOCLK / (M2 × 2) = DCOCLK / 62. The M2 divider value is hardcoded in HW at 31 (0x1F).
The DPLL provides also control for the loop bandwidth (BW) by programming the [15:14] PLL_VIDEO2_LOOPBW and [13:12] PLL_VIDEO1_LOOPBW bit-fields of the CTRL_CORE_DSS_PLL_CONTROL register in the device Control Module. This allows better control over the jitter at lower M values. [New DRA7xxP feature versus DRA75x/DRA74x]