CY23FS08_12 Datasheet, PDF (1/15 Pages) Cypress Semiconductor – Failsafe™ 2.5 V/3.3 V Zero Delay Buffer

CY23FS08
Failsafe™ 2.5 V/3.3 V Zero Delay Buffer
Features
■ Internal DCXO for continuous glitch-free operation
■ Zero input-output propagation delay
■ 100 ps typical output cycle-to-cycle jitter
■ 110 ps typical output-output skew
■ 1 MHz to 200 MHz reference input
■ Supports industry standard input crystals
■ 200 MHz (commercial), 166 MHz (industrial) outputs
■ 5 V-tolerant inputs
■ Phase-locked loop (PLL) bypass mode
■ Dual reference inputs
■ 28-pin SSOP
■ Split 2.5 V or 3.3 V output power supplies
■ 3.3 V core power supply
■ Industrial temperature available
Logic Block Diagram
REFSEL
REF1
REF2
FBK
XIN XOUT
DCXO
Failsafe^TM
Block
S[4:1]
Decoder
4
Functional Description
The CY23FS08 is a FailSafe™ Zero Delay Buffer with two
reference clock inputs and eight phase-aligned outputs. The
device provides an optimum solution for applications where
continuous operation is required in the event of a primary clock
failure.
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 CY23FS08 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
resynchronizes to the external clock.
The frequency of the crystal connected to the DCXO, must be
chosen to be an integer factor of the frequency of the reference
clock. This factor is set by four select lines: S[4:1]. see Table 2.
The CY23FS08 has three split power supplies; one for core,
another for Bank A outputs, and the third for Bank B outputs.
Each output power supply, except VDDC can be connected to
either 2.5 V or 3.3 V. VDDC is the power supply pin for internal
circuits and must be connected to 3.3 V.
4
CLKA[1:4]
PLL
4
CLKB[1:4]
FAIL# /SAFE
Cypress Semiconductor Corporation • 198 Champion Court
Document Number: 38-07518 Rev. *F
• San Jose, CA 95134-1709 • 408-943-2600
Revised January 7, 2011
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