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6.7.4

Clock PLL Electrical Data/Timing (Input and Output Clocks)

MXI/CLKIN

CLK_OUT0

(Divide-by-1)

TMS320DM6431

Digital Media Processor

www.ti.com

SPRS342C – NOVEMBER 2006 – REVISED JUNE 2008

Table 6-19. Timing Requirements for MXI/CLKIN (-3/-3Q/-3S) Devices(1)(2)(3)(4) (see Figure 6-12)

-3/-3Q/-3S

NO.

UNIT

MIN

MAX

tc(MXI)

Cycle time, MXI/CLKIN

33.3

tw(MXIH)

Pulse duration, MXI/CLKIN high

0.45C

0.55C

tw(MXIL)

Pulse duration, MXI/CLKIN low

0.45C

0.55C

tt(MXI)

Transition time, MXI/CLKIN

0.05C

tJ(MXI)

Period jitter, MXI/CLKIN

0.02C

(1)

The MXI/CLKIN frequency and PLL multiply factor should be chosen such that the resulting clock frequency is within the specific range

for CPU operating frequency. The resulting clock frequency should also meet the PLL requirements discussed in Section 6.7.1, PLL1

and PLL2. For example, for a -3/-3Q/-3S speed device with a 27 MHz CLKIN frequency, the PLL multiply factor should be

≤ 22. To get a

≤ 600 MHz PLL output frequency, SYSCLK1 should be set to a PLL output frequency of divide-by-2 to get ≤ 300 MHz device speed.

(2)

The reference points for the rise and fall transitions are measured at VIL MAX and VIH MIN.

(3)

For more details on the PLL multiplier factors, see the TMS320DM63x DMP DSP Subsystem Reference Guide (literature number

SPRU978).

(4)

C = CLKIN cycle time in ns. For example, when MXI/CLKIN frequency is 27 MHz, use C = 37.037 ns.

Figure 6-12. MXI/CLKIN Timing

Table 6-20. Switching Characteristics Over Recommended Operating Conditions for CLKOUT0(1)(2)

(see Figure 6-13)

-3/-3Q/-3S

NO.

PARAMETER

UNIT

MIN

MAX

Cycle time, CLKOUT0

33.3

tw(CLKOUT0H)

Pulse duration, CLKOUT0 high

0.45P

0.55P

tw(CLKOUT0L)

Pulse duration, CLKOUT0 low

0.45P

0.55P

tt(CLKOUT0)

Transition time, CLKOUT0

0.05P

(1)

The reference points for the rise and fall transitions are measured at VOL MAX and VOH MIN.

(2)

P = 1/CLKOUT0 clock frequency in nanoseconds (ns). For example, when CLKOUT0 frequency is 27 MHz, use P = 37.04 ns.

Figure 6-13. CLKOUT0 Timing

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