XRK7955 Datasheet, PDF (6/10 Pages) Exar Corporation – INTELLIGENT DYNAMIC CLOCK SWITCH PLL CLOCK DRIVER

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REV. P1.0.1
PRELIMINARY
XRK7955
INTELLIGENT DYNAMIC CLOCK SWITCH PLL CLOCK DRIVER
AC CHARACTERISTICS (V_CC= 3.3 + 5%, T_A= -40°C TO +85°C) (NOTE 5) ^f
SYMBOL
PARAMETER
MIN
TYP
MAX
UNIT
CONDITION
f_ref Input Reference Frequency ÷10 feedback
20
40
MHz
Locked
f_VCO PLL VCO Lock Range
200
400
MHz Qa Output used
for feedback
f_MAX Output Frequency
Qa[1:0] 20
Qa[1:0] 100
MHz
40
200
f_refDC Reference Input Duty Cycle
25
75
%
t_pd Propagation Delay
CLKn to Ext_FB (SPO) ^c
CLKn to Q (Bypass)
-150
150
ps
PLL_EN = 1
5
ns
PLL_EN = 0
V_PP Differential input voltage (peak-to-peak)
0.25
1.3
V
V_CMR Differential input crosspoint voltage
V_CC-1.7
V_CC-0.3
V
t_skew
Output Skew
Within Qa[1:0] or Qb[2:0]
All outputs
50
ps
80
ps
∆_per/cycle Rate of change of periods
Qa[1:0]^d
Qb[2:0]^d
Qa[1:0]^e
Qb[2:0]^e
50
ps/cycle
25
400
200
t_pw Output duty cycle
45
55
%
t_jitter Cycle-to-cyle jitter, Standard deviation (RMS)
40
ps
@f_ref = 30MHz
t_lock Maximum PLL lock time
10
ms
t_r/t_f Output Rise/Fall time
50
700
ps
c. Static phase offset between the selected reference clock and the feedback signal.
d. Specification holds for a clock switch between two signals no greater than 400ps out of phase. Delta period change
per cycle is averaged over the clock switch excursion. (See Applications Information section for more detail)
e. Specification holds for a clock switch between two signals no greater than ±π out of phase. Delta period change per
cycle is averaged over the clock switch excursion.
f. PECL output termination is 50 ohms to VCC – 2.0V.
g. V_PP is the minimum differential input voltage swing required to maintain AC characteristic including SPO, device and
part-to-part skew. Applicable to CLK0, CLK1 and Ext_FB.
h. V_CMR is the crosspoint of the differential input signal. Normal operation is obtained when the crosspoint is within the
V_CMR range and the input swing lies within the V_PP specification. Violation of V_CMR or V_PP impacts the SPO, device
and part-to-part skew. Applicable to CLK0, CLK1 and Ext_FB.
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