CY28410

Rev 1.0, November 21, 2006

Page 7 of 17

Crystal Recommendations

The CY28410 requires a Parallel Resonance Crystal. Substi-

tuting a series resonance crystal will cause the CY28410 to

operate at the wrong frequency and \violate the ppm specifi-

cation. For most applications there is a 300ppm frequency shift

between series and parallel crystals due to incorrect loading.

Crystal Loading

Crystal loading plays a critical role in achieving low ppm perfor-

mance. To realize low ppm performance, the total capacitance

the crystal will see must be considered to calculate the appro-

priate capacitive loading (CL).

The following diagram shows a typical crystal configuration

using the two trim capacitors. An important clarification for the

following discussion is that the trim capacitors are in series

with the crystal not parallel. It’s a common misconception that

load capacitors are in parallel with the crystal and should be

approximately equal to the load capacitance of the crystal.

This is not true.

2

Externally

selected

CPUT/C

FS_C. Reflects the value of the FS_C pin sampled on power-up

0 = FS_C was low during VTT_PWRGD# assertion

1

Externally

selected

CPUT/C

FS_B. Reflects the value of the FS_B pin sampled on power-up

0 = FS_B was low during VTT_PWRGD# assertion

0

Externally

selected

CPUT/C

FS_A. Reflects the value of the FS_A pin sampled on power-up

0 = FS_A was low during VTT_PWRGD# assertion

Byte 7: Vendor ID

Bit

@Pup

Name

Description

7

0

Revision Code Bit 3

Revision Code Bit 3

6

0

Revision Code Bit 2

Revision Code Bit 2

5

1

Revision Code Bit 1

Revision Code Bit 1

4

0

Revision Code Bit 0

Revision Code Bit 0

3

1

Vendor ID Bit 3

Vendor ID Bit 3

2

0

Vendor ID Bit 2

Vendor ID Bit 2

1

0

Vendor ID Bit 1

Vendor ID Bit 1

0

0

Vendor ID Bit 0

Vendor ID Bit 0

Byte 6: Control Register 6 (continued)

Bit

@Pup

Name

Description

Table 5. Crystal Recommendations

Frequency

(Fund)

Cut

Loading Load Cap

Drive

(max.)

Shunt Cap

(max.)

Motional

(max.)

Tolerance

(max.)

Stability

(max.)

Aging

(max.)

14.31818 MHz

AT

Parallel

20 pF

0.1 mW

5 pF

0.016 pF

35 ppm

30 ppm

5 ppm