CY25701JXC/FJXC
Document #: 38-07684 Rev. *E
Page 2 of 7
Functional Description
The CY25701JXC/FJXC is a Spread Spectrum Crystal Oscil-
lator (SSXO) IC used for the purpose of reducing EMI found in
today’s high-speed digital electronic systems.
The device uses a Cypress proprietary PLL and Spread
Spectrum Clock (SSC) technology to synthesize and modulate
the frequency of the embedded input crystal. By frequency
modulating the clock, the measured EMI at the fundamental
and harmonic frequencies are greatly reduced. This reduction
in radiated energy can significantly reduce the cost of
complying with regulatory agency (EMC) requirements and
improve time-to-market without degrading system perfor-
mance.
The CY25701JXC/FJXC uses a programmable configuration
memory array to synthesize output frequency and spread%.
The spread% is programmed to either center spread or down
spread with various spread percentages. The range for center
spread is from ±0.25% to ±2.00%. The range for down spread
is from –0.5% to –4.0%. Contact the factory for smaller or
larger spread% amounts if required. Refer to Table 2 for
spread selection and no-spread values.
The frequency modulated SSCLK output can be programmed
from 10–166 MHz.
The CY25701JXC/FJXC is available in a 4-pin plastic package
with operating temperature range of –20 to 70°C.
Programming Description
Field/Factory-Programmable CY25701JXC/FJXC
Field/Factory programming is available for samples and
manufacturing by Cypress and its distributors. All requests
must be submitted to the local Cypress Field Application
Engineer (FAE) or sales representative. Once the request has
been processed, you will receive a new part number, samples,
and data sheet with the programmed values. This part number
will be used for additional sample requests and production
orders.
Additional information on the CY25701JXC/FJXC can be
obtained from the Cypress web site at www.cypress.com.
Output Frequency, SSCLK Output (SSCLK, pin 3)
The modulated frequency at the SSCLK output is produced by
synthesizing from the embedded crystal oscillator frequency
input. The range of synthesized clock is from 10–166 MHz.
Spread Percentage (SSCLK, pin 3)
The SSCLK spread can be programmed to various spread
percentage values from ±0.25% to ±2.0% for Center Spread
and from –0.5% to –4.0% for Down Spread. Refer to Table 2
for available spread options. Enter ±0.0% (No spread) for XO
(Crystal Oscillator) without spread option.
Frequency Modulation (SSCLK, pin 3)
The frequency modulation is programmed at 31.5 kHz for all
SSCLK frequencies from 10 to 166 MHz. Contact the factory
if a higher-modulation frequency is required.
Note:
1. ±0.0% or Code “Z” for XO (No-Spread) option.
Pin Definition
Pin
Name
Description
1OE
Output Enable pin: Active HIGH. If OE = 1, SSCLK is enabled.
2
VSS
Power supply ground.
3
SSCLK
Spread spectrum clock output (with or without spread).
4VDD
3.3V power supply.
Table 1. Programming Data Requirement
Pin Function
Output Frequency
Spread Percent Code[1]
Frequency Modulation
Pin Name
SSCLK
SSCLK
SSCLK
Pin#
3
3
3
Units
MHz
%
kHz
Program Value
ENTER DATA
ENTER DATA
31.5
Table 2. Spread Percent Selection
Center Spread
Code
A
B
C
D
E
F
Z
Percentage
±0.25%
±0.5%
±0.75%
±1.0%
±1.5%
±2.0%
±0.0%
Down Spread
Code
G
H
J
K
L
M
Z
Percentage
–0.5%
–1.0%
–1.5%
–2.0%
–3.0%
–4.0%
±0.0%
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