TNETV2685FIBZUT9 datasheet(66/191 Pages) TI1

66 / 191 page

TMS320DM647

TMS320DM648

SPRS372H – MAY 2007 – REVISED APRIL 2012

www.ti.com

As shown in Figure 6-5, the PLL1 controller features a software-programmable PLL multiplier controller

(PLLM) and seven dividers (PREDIV, D1, D2, D3, D4, D5). The PLL1 controller uses the device input

clock CLKIN1 to generate a system reference clock (SYSREFCLK) and system clocks (SYSCLK1,

SYSCLK2, SYSCLK3, SYSCLK4, SYSCLK5). PLL1 power is supplied externally via the PLL1 power-

supply pin (PLLV1). An external EMI filter circuit must be added to PLLV1. The 1.8-V supply of the EMI

filter must be from the same 1.8-V power plane supplying the I/O power-supply pin, DVDD18. TI requires

EMI filter manufacturer Murata, part number NFM18CC222R1C3.

All PLL external components (C1, C2, and the EMI Filter) must be placed as close to the C64x+ DSP

device as possible. 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 the ones shown. For

reduced PLL jitter, maximize the spacing between switching signals and the PLL external components

(C1, C2, and the EMI Filter). The minimum CLKIN1 rise and fall times should also be observed. For the

input clock timing requirements, see Section 6.4.4.

6.4.1

PLL1 Controller Device-Specific Information

As shown in Figure 6-5, the PLL1 controller generates several internal clocks including the system

reference clock (SYSREFCLK), and the system clocks (SYSCLK1/2/3/4/5/6). The high-frequency clock

signal SYSREFCLK is directly used to clock the C64x+ megamodule (including the CPU) and also serves

as a reference clock for the rest of the DSP system. Dividers D1, D2, D3, D4, D5, and D6 divide the high-

frequency clock SYSREFCLK to generate SYSCLK1, SYSCLK2, SYSCLK3, SYSCLK4, SYSCLK5, and

SYSCLK6, respectively.

The system clocks are used to clock different portions of the DSP as follows:

•

SYSCLK1 is used for the following modules: 3PDMA, the SCR and the bridges, DDR Subsystem

internal logic, Video Port 0, Video Port 1, Video Port 2, Video Port 3, Video Port 4, EMIFA internal

logic.

•

SYSCLK2 is used for Emulation and Trace

•

SYSCLK3 is used for most of the peripherals. These modules are clocked from SYSCLK3: HPI, PCI,

VLYNQ, UART, I2C, TIMER 0, TIMER 1, TIMER 2, TIMER 3, SPI, McASP, VIC, GPIO, PLL Controller

1, PLL Controller 2, Config SCR

•

SYSCLK4 is used as the EMIFA AECLKOUT

[When SYSCLK4 is used as the EMIF input clock source, the actual clock goes through a divider and

the frequency would be SYSCLK4 divide-by-2 (see Figure 6-5, PLL Input Clock).]

•

SYSCLK5 is used as the VICP internal clock

•

SYSCLK6 is used as the VICP internal clock

The PLL multiplier controller (PLLM) must be programmed after reset. There is no hardware CLKMODE

selection on the device. Since the divider ratio bits for dividers D1, D3, D5, and D6 are fixed, the

frequency of SYSCLK1, SYCLK3, SYSCLK5, and SYSCLK6 is tied to the frequency of SYSREFCLK.

However, the frequency of SYSCLK2 and SYSCLK4 depends on the configuration of dividers D2 and D4.

For example, with PLLM in the PLL1 multiply control register set to 10011b (x20 mode) and a 35-MHz

CLKIN1 input, the PLL output PLLOUT is set to 700 MHz and SYSCLK1 and SYSCLK3 run at 233 MHz

and 117 MHz, respectively. Divider D4 can be programmed through the PLLDIV4 register to divide

SYSREFCLK by 8 (2 * (PLLDIV4.RATIO+1)) such that SYSCLK4 runs at 87.5 MHz.

Note that there is a minimum and maximum operating frequency for PLLREF, PLLOUT, and SYSCLK4.

The PLL1 Controller must not be configured to exceed any of these constraints (certain combinations of

external clock input, internal dividers, and PLL multiply ratios might not be supported). For the PLL clocks

input and output frequency ranges, see Table 6-6.

Peripheral Information and Electrical Specifications

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