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DESCRIPTION:
The FCT3932 uses phase-lock loop technology to lock the
frequency and phase of the feedback to the input reference
clock. It provides a large number of low skew outputs that are
configurable in 16 different modes using the CNTRL 1-4
inputs. A dedicated output, Q_FB, is provided to supply the
PLL feedback and it should be connected to the FEEDBACK
input. Q_FB is located adjacent to FEEDBACK to minimize
the delay in the feedback path. In order to offset any delay in
the output path from the FCT3932 output to a receiving device,
feedback path delay should be made to match this output path
delay.
The PLL consists of the phase/frequency detector, charge
pump, loop filter and VCO. The FCT3932 requires no external
loop filter components.
The FCT3932 provides 17 outputs grouped in 3 banks with
individual 3-state control and an additional dedicated feed-
back output with no disable. Connecting Q_FB to FEEDBACK
ensures uninterrupted PLL operation when all outputs are
disabled.
Individual bank 3-state allows users to disable unused
outputs in order to limit power dissipation or minimize switch-
ing noise. It also allows users to shut down outputs in low
power modes while maintaining phase lock.
The FCT3932 provides a LOCK pin that goes high when the
device is phase-locked.
The user can bypass the PLL for testability purposes by
deasserting PLL_EN. In this "test" mode, the input frequency
is not limited to the specified range.
The FCT3932 provides an asynchronous reset input,
,
which resets all outputs. This initializes all internal registers so
that outputs start up in a known state.
RST
APPLICATIONS:
SDRAM DIMM Clock, Caches, high speed microproces-
sors, motherboard clock distribution to DIMMs.
FUNCTIONAL BLOCK DIAGRAM
FEEDBACK
LOCK
Charge
Pump &
Loop Filter
Voltage
Controlled
Oscillator
REF_IN
Phase/Freq.
Detector
PLL_EN
0
Mux
1
OE
1
OE
2
OE
3
Q4
1-4
(BANK 1)
Q8
1-8
(BANK 2)
Q5
1-5
(BANK 3)
C
O
N
T
R
O
L
CNTRL1-4
Q_FB
RST
The IDT logo is a registered trademark of Integrated Device Technology, Inc.
3267 drw 01
COMMERCIAL TEMPERATURE RANGE
漏1996
Integrated Device Technology, Inc.
NOVEMBER 1996
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