TMS320C6678
Multicore Fixed and Floating-Point Digital Signal Processor
SPRS691D—April 2013
www.ti.com
Table 7-26
Main PLL Controller/SRIO/HyperLink/PCIe Clock Input Timing Requirements (1) (Part 3 of 3)
(see Figure 7-19 and Figure 7-20)
No.
Min
Max Unit
4 (2) ps,RMS
4 (2) ps,RMS
5
5
tj(PCIECLKN)
tj(PCIECLKP)
Jitter, peak_to_peak _ periodic PCIECLKN
Jitter, peak_to_peak _ periodic PCIECLKP
End of Table 7-26
1 See the Hardware Design Guide for KeyStone devices in ‘‘Related Documentation from Texas Instruments’’ on page 73 for detailed recommendations.
2 The jitter frequency mask shown in the Hardware Design Guide for KeyStone Devices in ‘‘Related Documentation from Texas Instruments’’ on page 73 must also be met for
the specific operating mode chosen.
Figure 7-19
Figure 7-20
Main PLL Controller/SRIO/HyperLink/PCIe Clock Input Timing
1
2
3
5
<CLK_NAME>CLKN
<CLK_NAME>CLKP
4
Main PLL Clock Input Transition Time
peak-to-peak differential input
250 mV peak-to-peak
0
voltage (250 mV to 2 V)
TR = 50 ps min to 350 ps max (10% to 90 %)
for the 250 mV peak-to-peak centered at zero crossing
7.6 DD3 PLL
The DDR3 PLL generates interface clocks for the DDR3 memory controller. When coming out of power-on reset,
DDR3 PLL is programmed to a valid frequency during the boot config before being enabled and used.
DDR3 PLL power is supplied externally via the DDR3 PLL power-supply pin (AVDDA2). An external EMI filter
circuit must be added to all PLL supplies. See the Hardware Design Guide for KeyStone Devices in ‘‘Related
Documentation from Texas Instruments’’ on page 73. For the best performance, TI recommends that all the PLL
external components be on a single side of the board without jumpers, switches, or components other than those
shown. For reduced PLL jitter, maximize the spacing between switching signal traces and the PLL external
components (C1, C2, and the EMI filter).
Figure 7-21 shows the DDR3 PLL.
Figure 7-21
DDR3 PLL Block Diagram
DDR3 PLL
PLLD xPLLM /2
0
1
DDRCLK(N|P)
PLLOUT
DDR3
PHY
BYPASS
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Peripheral Information and Electrical Specifications 151
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