JAJSDV6F November 2009 – January 2017 TMS320C6746
PRODUCTION DATA.
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The device DSP generates the high-frequency internal clocks it requires through an on-chip PLL.
The PLL requires some external filtering components to reduce power supply noise as shown in Figure 6-8.
The external filtering components shown above provide noise immunity for the PLLs. PLL0_VDDA and PLL1_VDDA should not be connected together to provide noise immunity between the two PLLs. Likewise, PLL0_VSSA and PLL1_VSSA should not be connected together.
The input to the PLL is either from the on-chip oscillator or from an external clock on the OSCIN pin. PLL0 outputs seven clocks that have programmable divider options. PLL1 outputs three clocks that have programmable divider options. Figure 6-9 illustrates the high-level view of the PLL Topology.
The PLLs are disabled by default after a device reset. They must be configured by software according to the allowable operating conditions listed in Table 6-4 before enabling the device to run from the PLL by setting PLLEN = 1.
NO. | PARAMETER | Default
Value |
MIN | MAX | UNIT |
---|---|---|---|---|---|
1 | PLLRST: Assertion time during initialization | N/A | 1000 | N/A | ns |
2 | Lock time: The time that the application has to wait for the PLL to acquire lock before setting PLLEN, after changing PREDIV, PLLM, or OSCIN | N/A | N/A | (1) | OSCIN
cycles |
3 | PREDIV: Pre-divider value | /1 | /1 | /32 | - |
4 | PLLREF: PLL input frequency | 12 | 30 (if internal oscillator is used)
50 (if external clock is used) |
MHz | |
5 | PLLM: PLL multiplier values | x20 | x4 | x32 | |
6 | PLLOUT: PLL output frequency | N/A | 300 | 600 | MHz |
7 | POSTDIV: Post-divider value | /1 | /1 | /32 | - |