CY2XF23

Document Number: 001-53145 Rev. *E

Page 5 of 16

Programming Description

The CY2XF23 is a programmable device. Before being used in

an application, it must be programmed with the output

frequencies and other variables described in Programming

Variables on page 5. Two different device types are available,

each with its own programming flow. They are described in the

following sections.

Field-Programmable CY2XF23F

Field programmable devices are shipped unprogrammed and

must be programmed before being installed on a printed circuit

board (PCB). Customers use CyClockWizard™ software to

specify the device configuration and generate a joint electron

devices

engineering

council

(JEDEC - extension .jed)

programming file. Programming of samples and prototype

quantities is available using the CyClockWizard software along

with a CY3675-CLKMAKER1 CyClockMaker Clock Programmer

Kit with a CY3675-LCC6A socket adapter. 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 software and programmer kit hardware

can be downloaded from www.cypress.com by clicking the

hyperlinks above.

Factory-Configured CY2XF23

For ready-to-use devices, the CY2XF23 is available with no field

programming required. Pre-configured devices (see Standard

and Application-Specific Factory Configurations) are available

for samples or orders, or a request for a custom configuration

can be made. All requests are submitted to the local Cypress

Field Application Engineer (FAE) or sales representative. After

the request is processed, the user receives a new part number,

samples, and datasheet with the programmed values. This part

number is used for additional sample requests and production

orders. The CY2XF23 is one-time programmable (OTP).

Programming Variables

Output Frequencies

The CY2XF23 is programmed with up to four independent output

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 CY2XF23 has an output frequency range of 50 MHz to

690 MHz, but the range is not continuous. The CY2XF23 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. They have a potentially significant impact on

performance levels for applications requiring the lowest possible

phase noise. CyClockWIzard software allows the user to select

between and view the expected performance of both options.

Memory Map

define the output frequency. As shown in Table 2, each of these

words is a 6-byte field. When writing to a frequency word, all six

bytes should be written. They may be written either as individual

byte writes, or as a block write. The currently selected frequency

word should not be written to. All four words are symmetrical,

meaning that a 6-byte value that is valid for one word is also valid

for any of the other words, and produces the same frequency.

The fifth field is the select byte, located at byte address 40h. The

value written into the two least significant bits determines the

active frequency word. The other bits of the byte are reserved

and must be written with the values indicated in the table. Users

should never write to any address other than the 25 bytes

described here.

Serial Interface Protocol and Timing

operates up to 100 kbits/sec in read or write mode. The

CY2XF23 is always a slave on this bus, meaning that it never

initiates a bus transaction. The basic write protocol is as follows:

Start Bit; 7-bit Device Address (DA); R/W Bit; Slave Clock

Acknowledge (ACK); 8-bit Memory Address (MA); ACK; 8-bit

Data; ACK; 8-bit Data in MA+1 if desired; ACK; 8-bit Data in

MA+2; ACK; and so on, until STOP Bit. The basic serial format

is illustrated in Figure 4 on page 7.

Table 1. Device Programming Variables

Variable

Output frequency 0

Output frequency 1

Output frequency 2

Output frequency 3

Temperature range (commercial or industrial)

Table 2. Frequency Words

Frequency

Word

Byte Addresses

(hex)

Word Select

(Select Byte 40h)

0

10h to 15h

00

1

16h to 1Bh

01

2

1Ch to 21h

10

3

22h to 27h

11

Table 3. Register 40h: Select Byte

Bits

Default Value

(binary)

Name

Description

7:2 000000

Reserved

Reserved. Always write

this value.

1:0 User-defined

Word select Selects the Frequency

Word to determine the

output frequency. 00

selects Word 0; 01

selects Word 1; 10

selects Word 2; 11

selects Word 3.

[+] Feedback