TMS320VC5407 datasheet(75/110 Pages) TI

75 / 110 page

Electrical Specifications

November 2001 − Revised April 2004

SPRS007D

5.7.2 Multiply-By-N Clock Option (PLL Enabled)

The frequency of the reference clock provided at the X2/CLKIN pin can be multiplied by a factor of N to

generate the internal machine cycle. The selection of the clock mode and the value of N is described in

Section 3.10. Following reset, the software PLL can be programmed for the desired multiplication factor. Refer

to the TMS320C54x DSP Reference Set, Volume 1: CPU and Peripherals (literature number SPRU131) for

detailed information on programming the PLL.

When an external clock source is used, the external frequency injected must conform to specifications listed

in Table 5−6.

Table 5−6 and Table 5−7 assume testing over recommended operating conditions and H = 0.5tc(CO) (see

Figure 5−4).

Table 5−6. Multiply-By-N Clock Option Timing Requirements

MIN

MAX

UNIT

Integer PLL multiplier N (N = 1−15)†

200

tc(CI)

Cycle time, X2/CLKIN

PLL multiplier N = x.5†

100

tc(CI)

Cycle time, X2/CLKIN

PLL multiplier N = x.25, x.75†

tf(CI)

Fall time, X2/CLKIN

tr(CI)

Rise time, X2/CLKIN

tw(CIL)

Pulse duration, X2/CLKIN low

tw(CIH)

Pulse duration, X2/CLKIN high

† N is the multiplication factor.

Table 5−7. Multiply-By-N Clock Option Switching Characteristics

PARAMETER

MIN

TYP

MAX

UNIT

tc(CO)

Cycle time, CLKOUT

8.33

td(CI-CO)

Delay time, X2/CLKIN high/low to CLKOUT high/low

tf(CO)

Fall time, CLKOUT

tr(CO)

Rise time, CLKOUT

tw(COL)

Pulse duration, CLKOUT low

tw(COH)

Pulse duration, CLKOUT high

Transitory phase, PLL lock-up time

tc(CO)

tc(CI)

tw(COH)

tf(CO)

tr(CO)

tf(CI)

X2/CLKIN

CLKOUT

td(CI-CO)

tw(COL)

tr(CI)

Unstable

tw(CIH)

tw(CIL)

NOTE A: The CLKOUT timing in this diagram assumes the CLKOUT divide factor (DIVFCT field in the BSCR) is configured as 00 (CLKOUT not

divided). DIVFCT is configured as CLKOUT divided-by-4 mode following reset.

Figure 5−4. Multiply-by-One Clock Timing

TMS320VC5407 Datasheet(PDF) 75 Page - Texas Instruments

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