CY2XF34

Document Number: 001-53149 Rev. *D

Page 2 of 10

Functional Description

The FS0 and FS1 pins select between four different output

frequencies, as shown in Table 1. Frequency margining is a

common application for this feature. One frequency is used for

the standard operating mode of the device, while the other

frequencies are available for margin testing, either during

product development or in system manufacturing test.

When changing the output frequency, the frequency transition is

not guaranteed to be smooth. There can be frequency

excursions beyond the start frequency and the new frequency.

Glitches and runt pulses are possible, and time must be allowed

for the PLL to relock.

Programming Description

The CY2XF34 is a programmable device. Before being used in

an application, it must be programmed with the output

frequencies and other variables described in a later section. Two

different device types are available, each with its own

programming flow. They are described in the following sections.

Field Programmable CY2XF34F

Field programmable devices are shipped unprogrammed and

must be programmed before being installed on a printed circuit

board (PCB). Customers use CyberClocks™ Online Software to

specify the device configuration and generate a JEDEC

(extension .jed) programming file. Programming of samples and

prototype quantities is available using a Cypress programmer.

Third party vendors manufacture programmers for small to large

volume applications. Cypress’s value added distribution partners

also provide programming services. Field programmable

devices are designated with an “F” in the part number. They are

intended for quick prototyping and inventory reduction. The

CY2XF34 is One Time Programmable (OTP).

Factory Configured CY2XF34

For customers wanting ready-to-use devices, the CY2XF34 is

available with no field programming required. All requests are

submitted to the local Cypress Field Application Engineer (FAE)

or sales representative. After the request is processed, you

receive a new part number, samples, and datasheet with the

programmed values. This part number is used for additional

sample requests and production orders.

Programming Variables

Output Frequencies

The CY2XF34 is programmed with up to four independent output

frequencies, which are then selected using the FS0 and FS1

pins. The device can synthesize frequencies to a resolution of

1 part per million (ppm), but the actual accuracy of the output

frequency is limited by the accuracy of the integrated reference

crystal.

The CY2XF34 has an output frequency range of 50 MHz to

690 MHz, but the range is not continuous. The CY2XF34 cannot

generate frequencies in the ranges of 521 MHz to 529 MHz, and

596 MHz to 617 MHz.

Industrial Versus Commercial Device Performance

Industrial and Commercial devices have different internal

crystals. This has a potentially significant impact on performance

levels for applications requiring the lowest possible phase noise.

CyberClocks Online Software displays expected performance

for both options.

Phase Noise Versus Jitter Performance

In most cases, the device configuration for optimal phase noise

performance is different from the device configuration for optimal

cycle to cycle or period jitter. CyberClocks Online Software

includes algorithms to optimize performance for either

parameter.

Table 1. Frequency Select

FS1

FS0

Output Frequency

0

0

Frequency 0

0

1

Frequency 1

1

0

Frequency 2

1

1

Frequency 3

Table 2. Device Programming Variables

Variable

Output Frequency 0 (Power on default)

Output Frequency 1

Output Frequency 2

Output Frequency 3

Optimization (phase noise or jitter)

Temperature range (Commercial or Industrial)

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