IDT5991A-5 Integrated Device Technology, IDT5991A-5 Datasheet - Page 3
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IDT5991A-5
Manufacturer Part Number
IDT5991A-5
Description
Programmable Skew Pll Clock Driver Turboclock
Manufacturer
Integrated Device Technology
Datasheet
1.IDT5991A-5.pdf
(8 pages)
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PLL PROGRAMMABLE SKEW RANGE AND RESOLUTION TABLE
NOTES:
1. The device may be operated outside recommended frequency ranges without damage, but functional operation is not guaranteed. Selecting the appropriate FS value based on
2. The level to be set on FS is determined by the nominal operating frequency of the VCO and Time Unit Generator. The VCO frequency always appears at 1Q
3. Skew adjustment range assumes that a zero skew output is used for feedback. If a skewed Q output is used for feedback, then adjustment range will be greater. For example
CONTROL SUMMARY TABLE FOR FEEDBACK SIGNALS
NOTES:
1.
2.
EXTERNAL FEEDBACK
with regard to skew adjustment. The FB signal is compared with the
input REF signal at the phase detector in order to drive the VCO. Phase
differences cause the VCO of the PLL to adjust upwards or downwards
accordingly.
IDT5991A
PROGRAMMABLE SKEW PLL CLOCK DRIVER TURBOCLOCK
Timing Unit Calculation (t
VCO Frequency Range (F
Skew Adjustment Range
Max Adjustment:
Example 1, F
Example 2, F
Example 3, F
Example 4, F
Example 5, F
Example 6, F
input frequency range allows the PLL to operate in its ‘sweet spot’ where jitter is lowest.
higher outputs when they are operated in their undivided modes. The frequency appearing at the REF and FB inputs will be the same as the VCO when the output connected
to FB is undivided. The frequency of the REF and FB inputs will be 1/2 or 1/4 the VCO frequency when the part is configured for a frequency multiplication by using a divided
output as the FB input.
if a 4t
applies to output pairs 3 and 4 where ± 6t
By providing external feedback, the IDT5991A gives users flexibility
LL disables outputs if TEST = MID and GND/sOE = HIGH.
When pair #4 is set to HH (inverted), GND/sOE disables pair #4 HIGH when V
U
skewed output is used for feedback, all other outputs will be skewed –4t
NOM
NOM
NOM
NOM
NOM
NOM
nF1:0
LL
M M
M H
H M
H H
LM
ML
LH
HL
= 15MHz
= 25MHz
= 30MHz
= 40MHz
= 50MHz
= 80MHz
(1)
(3)
U
)
NOM
)
(1,2)
U
skew adjustment is possible and at the lowest F
Skew (Pair #1, #2)
1/(44 x F
Zero Skew
15 to 35MHz
FS = LOW
t
t
t
U
U
U
±9.09ns
±14%
–4t
–3t
–2t
–1t
= 1.52ns
= 0.91ns
= 0.76ns
1t
2t
3t
4t
±49º
U
U
U
U
—
—
—
U
U
U
U
NOM
)
U
CCQ
in addition to whatever skew value is programmed for those outputs. ‘Max adjustment’ range
/PE = HIGH, GND/sOE disables pair #4 LOW when V
3
phase detector. The loop filter transfer function has been chosen to
provide minimal jitter (or frequency variation) while still providing accu-
rate responses to input frequency changes.
An internal loop filter moderates the response of the VCO to the
1/(26 x F
25 to 60MHz
t
t
t
t
NOM
FS = MID
U
U
U
U
±9.23ns
±23%
= 1.54ns
= 1.28ns
= 0.96ns
= 0.77ns
COMMERCIAL AND INDUSTRIAL TEMPERATURE RANGES
±83º
—
—
value.
Skew (Pair #3)
NOM
Divide by 2
Divide by 4
Zero Skew
–6t
–4t
–2t
)
2t
4t
6t
U
U
U
U
U
U
40 to 100MHz
1/(16 x F
FS = HIGH
t
t
t
U
U
U
±9.38ns
±37%
= 1.56ns
= 1.25ns
= 0.78ns
±135º
—
—
—
NOM
)
CCQ
/PE = LOW.
Skew (Pair #4)
Divide by 2
Zero Skew
Inverted
% of Cycle Time
Phase Degrees
–6t
–4t
–2t
2t
4t
6t
Comments
U
U
U
U
U
U
(2)
ns
1:0
, 2Q
1:0
, and the