1
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All data sheets are subject to change without notice
(858) 503-3300 - Fax: (858) 503-3301 - wwwmaxwell.com
Programmable Skew
Clock Buffer (PSCB)
7B991
2002 Maxwell Technologies.
All rights reserved.
09.23.02 Rev 4
F
EATURES
:
All output pair skew < 100 ps typical (250 max.)
3.75 to 80 MHz output operation
User-selectable output functions
Selectable skew to 18 ns
Inverted and non-inverted
Operation at and input frequency
Operation at 2x and 4x input frequency (input as low as
3.75 MHz)
Zero input to output delay
50% duty-cycle outputs
Outputs drive 50
termnated lines
Low operating current
Package: 32-pin R
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flat package
Jitter < 200 ps peak-to-peak (< 25 ps RMS)
Compatible with Pentium-based processor
Total dose hardness:
- >100 krads (Si), depending upon space mssion
Excellent Single Event Effects:
- SEL > 116MeV/mg/cm
2
- SEU
TH
-3 MeV/mg/cm
2
- SEU sat cross section: 1E-3/device
D
ESCRIPTION
:
Maxwell Technologies’ 7B991 Programmable Skew Clock
Buffers (PSCB) offer user-selectable control over system
clock functions. These multiple-output clock drivers provide
the systemintegrator with functions necessary to optimze tim-
ing of high-performance computer systems. Eight individual
drivers, arranged as four pairs of user-controllable outputs,
can each drive termnated transmssion lines with impedances
as low as 50
while delivering mnimal and specified output
skews and full-swing logic levels.
Each output can be hardwired to one of nine delay or function
configurations. Delay increments of 0.7 to 1.5 ns are deter-
mned by the operating frequency with outputs able to skew up
to ± 6 time units fromtheir nomnal “zero” skew position. The
completely integrated PLL allows external load and transms-
sion line delay effects to be canceled. When this “zero delay”
capability of the PSCB is combined with the selectable output
skew functions, the user can create output-to-output delays of
up to ±12 time units.
Maxwell Technologies' patented R
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packaging technol-
ogy incorporates radiation shielding in the mcrocircuit pack-
age. It elimnates the need for box shielding while providing
the required radiation shielding for a lifetime in orbit or space
mssion. In a GEO orbit, R
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AK
provides greater than 100
krad (Si) radiation dose tolerance. This product is available
with screening up to Class S.
Logic Diagram