DSP56321RMSLASHD datasheet(29/88 Pages) NXP

29 / 88 page

2-5

AC Electrical Characteristics

Note:

If an externally-supplied square wave voltage source is used, disable the internal oscillator

circuit during bootup by setting XTLD (PCTL Register bit 2 = 1—see the DSP56321T

Reference Manual). The external square wave source connects to EXTAL; XTAL is not

physically connected to the board or socket. Figure 2-2 shows the EXTAL input and the internal

clock signals.

Table 2-5. External Clock Operation

No.

Characteristics

Symbol

220 MHz

240 MHz

Min

Max

Min

Max

Frequency of EXTAL (EXTAL Pin Frequency)1

•

With DPLL disabled

•

With DPLL enabled2

DEFR = PDF

× PDFR

0 MHz

16 MHz

220 MHz

0 MHz

16 MHz

240 MHz

EXTAL input high3

•

With DPLL disabled (46.7%–53.3% duty cycle4)

•

With DPLL enabled (42.5%–57.5% duty cycle4)

ETH

2.13 ns

1.93 ns

∞

35.9 ns

1.95 ns

1.77 ns

∞

35.9 ns

EXTAL input low4

•

With DPLL disabled (46.7%–53.3% duty cycle4)

•

With DPLL enabled (42.5%–57.5% duty cycle4)

ETL

2.13 ns

1.93 ns

∞

35.9 ns

1.95 ns

1.77 ns

∞

35.9 ns

EXTAL cycle time3

•

With DPLL disabled

•

With DPLL enabled

ETC

4.55 ns

∞

62.5 ns

4.17 ns

∞

62.5 ns

Instruction cycle time = ICYC = ETC

•

With DPLL disabled

•

With DPLL enabled

ICYC

9.1 ns

4.55 ns

∞

1.6

µs

8.34 ns

4.17 ns

∞

1.6

µs

Notes:

The rise and fall time of this external clock should be 2 ns maximum.

Refer to Table 2-6 for a description of PDF and PDFR.

Measured at 50 percent of the input transition.

The indicated duty cycle is for the specified maximum frequency for which a part is rated. The minimum clock

high or low time required for correction operation, however, remains the same at lower operating frequencies;

therefore, when a lower clock frequency is used, the signal symmetry may vary from the specified duty cycle as

long as the minimum high time and low time requirements are met.

Figure 2-2. External Input Clock Timing

EXTAL

VILX

VIHX

Midpoint

Note:

The midpoint is 0.5 (VIHX + VILX).

ETH

ETL

ETC

Freescale Semiconductor, Inc.

For More Information On This Product,

Go to: www.freescale.com

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