CY23FS04 Datasheet, PDF (1/12 Pages) Cypress Semiconductor – Failsafe 2.5V/ 3.3V Zero Delay Buffer

CY23FS04
Failsafe™ 2.5V/ 3.3V Zero Delay Buffer
Features
• Internal DCXO for continuous glitch-free operation
• Zero input-output propagation delay
• Low-jitter (< 35 ps RMS) outputs
• Low Output-to-Output skew (< 200 ps)
• 4.17 MHz–170 MHz reference input
• Supports industry standard input crystals
• 170 MHz outputs
• 5V-tolerant inputs
• Phase-locked loop (PLL) Bypass Mode
• Dual Reference Inputs
• 16-pin TSSOP
• 2.5V or 3.3V output power supplies
• 3.3V core power supply
• Industrial temperature available
Block Diagram
Functional Description
The CY23FS04 is a FailSafe zero delay buffer with two
reference clock inputs and four phase-aligned outputs. The
device provides an optimum solution for applications where
continuous operation is required in the event of a primary clock
failure.
The continuous, glitch-free operation is achieved by using a
DCXO, which serves as a redundant clock source in the event
of a reference clock failure by maintaining the last frequency
and phase information of the reference clock.
The unique feature of the CY23FS04 is that the DCXO is in
fact the primary clocking source, which is synchronized
(phase-aligned) to the external reference clock. When this
external clock is restored, the DCXO automatically resynchro-
nizes to the external clock.
The frequency of the crystal, which will be connected to the
DCXO must be chosen to be an integer factor of the frequency
of the reference clock. This factor is set by two select lines:
S[2:1], please see Table 1. Output power supply, VDD can be
connected to either 2.5V or 3.3V. VDDC is the power supply
pin for internal circuits and must be connected to 3.3V.
Pin Configuration
REFSEL
XIN XOUT
DCXO
REF1
REF2
FBK
Failsafe^TM
Block
PLL
S[2:1]
Decoder
2
2
CLKA[1:2]
2
CLKB[1:2]
REF1 ₁
REF2 ₂
CLKB1 ₃
CLKB2 ₄
S2 ₅
VSS ₆
VDDC ₇
XIN 8
16 REFSEL
15 FBK
14 CLKA1
13 CLKA2
12 S1
11 VDD
10 FAIL#/SAFE
9 XOUT
16 pin TSSOP
FAIL# /SAFE
Cypress Semiconductor Corporation • 3901 North First Street • San Jose, CA 95134 • 408-943-2600
Document #: 38-07304 Rev. *B
Revised October 12, 2004