XRK4991 Datasheet, PDF (10/12 Pages) Exar Corporation – 3.3V HIGH-SPEED (85 MHZ) PROGRAMMABLE SKEW CLOCK BUFFER

XRK4991
3.3V HIGH-SPEED (85 MHZ) PROGRAMMABLE SKEW CLOCK BUFFER
xr
REV. 1.0.1
11. t_SKEWPR is defined as the skew between a pair of outputs (Qx0 and Qx1) when all eight outputs are selected for
0t_U.
12. t_SKEW0 is defined as the skew between outputs when they are selected for 0t_U. Other outputs are divided or
inverted but not shifted
13. There are three classes of outputs: Nominal (multiple of t_U delay), Inverted (QD[1:0] only with SELD0 = SELD1 =
HIGH), and Divided (QC[1:0] and QD[1:0] only in Divide-by-2 or Divide-by-4 mode).
14. Guaranteed by statistical correlation. Tested initially and after any design or process changes that may affect
these parameters.
15. t_DEV is the output-to-output skew between any two devices operating under the same conditions (V_CC ambient
temperature, air flow, etc.)
16. t_ODCV is the deviation of the output from a 50% duty cycle. Output pulse width variations are included in t_SKEW2
and t_SKEW4 specifications.
17. Specified with outputs loaded with 30pF for the XRK4991-5 and -7 devices. Devices are terminated through 50Ω
to V_CC/2. t_PWH is measured at 2.0V. t_PWL is measured at 0.8V.
18. t_ORISE and t_OFALL measured between 0.8V and 2.0V.
19. t_LOCK is the time that is required before synchronization is achieved. This specification is valid only after V_CC is
stable and within normal operating limits. This parameter is measured from the application of a new signal or
frequency at CLKIN or FB_IN until t_PD is within specified limits
FIGURE 6. AC TIMING DIAGRAMS
CLKIN
FB_IN
t_REF
t_RPWH
t_RPWL
t_PD
t_ODCV t_ODCV
Qxx output
Other Qxx output
Inverted Qxx output
CLKIN Divided by 2
CLKIN Divided by 4
t_SKEWPR,
t_{SKEW0, 1}
t_{SKEW3, 4}
t_{SKEW1, 3, 4}
t_SKEWPR,
t_{SKEW0, 1}
t_SKEW2
t_{SKEW3, 4}
t_JR
t_SKEW2
t_{SKEW3, 4}
t_{SKEW2, 4}
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