5.9.3.9 PLLs
Power is supplied to the PLLs by internal regulators that derive power from the off-chip power-supply.
There are seven Phase Locked Loops (PLLs) in the device:
- MAIN_PLL with PLL_CONTROLLER: (SoC, Peripherals) The Main PLL — which is used to drive the switch fabrics, accelerators, and a majority of the peripheral clocks — requires a PLL controller to manage the various clock divisions, gating, and synchronization.
- ARM_PLL: The ARM PLL, which is used to drive the ARMSS.
- DSS_PLL: (Display Subsystem) The DSS PLL, which is used to drive the DSS.
- UART_PLL: (ICSS UART) The UART PLL, which is used to drive the UART in ICSS, QSPI, MMC/SD and USB.
- ICSS_PLL: (ICSS PRUs) The ICSS PLL, which is used to drive the ICSS.
- NSS/IEP_PLL: (NSS, ICSS) The NSS/IEP PLL, which is used to drive the NSS_L and ICSS.
- DDR_PLL: (DDR EMIF / DDR PHY) The DDR PLL is used to drive the DDR EMIF PHY for the DDR EMIF.
Most of the Device is driven by the output from the main PLL except the following items:
- ARMSS has its own dedicated PLL.
- DDR subsystem has its own dedicated PLL which sources DDR EMIF and DDR EMIF PHY.
- ICSS receives clocks from several PLLs – MAIN_PLL, UART_PLL, ICSS_PLL, and NSS/IEP_PLL.
- DSS has its own dedicated PLL, which generates the DSS pixel clock.
- PCIe subsystem receives clocks from MAIN_PLL and the external 100 MHz reference clock input.
- USB has the option of being clocked from UART_PLL, NSS_PLL, or an optional external clock reference input.
NOTE
For more information, see:
- Device Configuration / Clock Management / PLLs section
- Peripherals / Display Subsystem Overview section of the Device TRM.
NOTE
The input reference clocks (SYSCLK_P/N or SYSOSC_IN) are specified and the lock time is guaranteed by the PLL controller, as documented in the Device Configuration chapter of the Device TRM.