
87974CYI
www.idt.com
REV. E JULY 26, 2010
1
ICS87974I
LOW SKEW, 1-TO-15,
LVCMOS/LVTTL CLOCK GENERATOR
GENERAL DESCRIPTION
The ICS87974I is a low skew, low jitter 1-to-15 LVCMOS/
LVTTL Clock Generator/Zero Delay Buffer. The device has
a fully integrated PLL and three banks whose divider ratios
can be independently controlled, providing output
frequency relationships of 1:1, 2:1, 3:1, 3:2, 3:2:1. In
addition, the external feedback connection provides for a
wide selection of output-to-input frequency ratios. The CLK0
and CLK1 pins allow for redundant clocking on the input
and dynamically switching the PLL between two clock
sources.
Guaranteed low jitter and output skew characteristics make
the ICS87974I ideal for those applications demanding well
defined performance and repeatability.
FEATURES
Fully integrated PLL
Fifteen single ended 3.3V LVCMOS/LVTTL outputs
Two LVCMOS/LVTTL clock inputs for redundant clock
applications
CLK0 and CLK1 accepts the following input levels:
LVCMOS/LVTTL
Output frequency range: 8.33MHz to 125MHz
VCO range: 200MHz to 500MHz
External feedback for ”zero delay” clock regeneration
Cycle-to-cycle jitter: ±100ps (typical)
Output skew: 350ps (maximum)
3.3V operating supply
-40°C to 85°C ambient operating temperature
Available in both standard and lead-free RoHS-compliant
packages
PIN ASSIGNMENT
V
DDOA
QA0
GND
QA1
V
DDOA
QA2
FB_SEL1
GND
QA3
V
DDOA
QA4
GND
FB_SEL0
GND
nMR/OE
CLK_EN
SEL_B
SEL_C
PLL_SEL
SEL_A
CLK_SEL
CLK0
CLK1
nc
VDD
VDDA
1
2
3
4
5
6
7
8
9
10
11
12
13
14 15 16 17 18 19 20 21 22 23 24 25 26
39
38
37
36
35
34
33
32
31
30
29
28
27
52 51 50 49 48 47 46 45 44 43 42 41 40
GND
QB1
VDDOB
QB2
GND
QB3
VDDOB
QB4
FB_IN
GND
QFB
VDDOFB
nc
QB0
V
DDOB
nc
GND
QC3
V
DDOC
QC2
GND
QC1
V
DDOC
QC0
GND
VCO_SEL
ICS87974I
52-Lead LQFP
10mm x 10mm x 1.4mm package body
Y package
Top View