MC68340 datasheet(107/441 Pages) FREESCALE

107 / 441 page

4- 10

MC68340 USER’S MANUAL

MOTOROLA

using crystal mode, the system clock frequency is programmable (using the W, X, and Y

bits in the SYNCR) over the range specified in Section 11 Electrical Characteristics

(see Table 4-2.).

EXTAL

PHASE

COMPARATOR

LOW-PASS

FILTER

VCO

CRYSTAL

OSCILLATOR

XTAL

XFC PIN

VDDSYN

XFC

VDDSYN

0.1

µF

0.01

µF

0.1

µF

NOTE 1: Must be low-leakage capacitor.

20 pF

20 M

÷4

MODULUS

DIVIDER

FEEDBACK DIVIDER

SEL

MUX

$3F

÷64

÷8

SEL

MUX

÷2

CLKOUT

Figure 4-4. Clock Block Diagram for Crystal Operation

XTAL

EXTAL

60 k

Ω

60 k

Ω

Figure 4-5. MC68340 Crystal Oscillator

A separate power pin (VCCSYN) is used to allow the clock circuits to run with the rest of

the device powered down and to provide increased noise immunity for the clock circuits.

The source for VCCSYN should be a quiet power supply with adequate external bypass

capacitors placed as close as possible to the VCCSYN pin to ensure a stable operating

frequency. Figure 4-4 shows typical values for the bypass and PLL external capacitors.

The crystal manufacturer's documentation should be consulted for specific

recommendations for external components.

Freescale Semiconductor, Inc.

For More Information On This Product,

Go to: www.freescale.com

MC68340 Scheda tecnica(PDF) 107 Page - Freescale Semiconductor, Inc

MC68340 Scheda tecnica(HTML) 107 Page - Freescale Semiconductor, Inc

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

Scheda tecnica Scarica

Link URL