ICS667-01
HDTV CLOCK SYNTHESIZER CLOCK SYNTHESIZER
IDT™ / ICS™
HDTV CLOCK SYNTHESIZER 2
ICS667-01 REV E 051310
Pin Assignment
Pin Descriptions
External Components
Decoupling Capacitor
As with any high performance mixed-signal IC, the
ICS667-01 must be isolated from system power supply
noise to perform optimally.
A decoupling capacitor of 0.01µF must be connected
between VDD and GND on pins 2 and 3. It must be
connected close to the ICS667-01 to minimize lead
inductance. Pin 5 can be connected to pin 3. No external
power supply filtering is required for the ICS667-01.
Series Termination Resistor
A 33Ω terminating resistor can be used next to the clock
outputs for trace lengths over one inch.
Crystal Load Capacitors
The total on-chip capacitance is approximately 18 pF. A
parallel resonant, fundamental mode, AT cut 27 MHz crystal
should be used. The device crystal connections should
include pads for small capacitors from X1 to ground and
from X2 to ground. These capacitors are used to adjust the
stray capacitance of the board to match the nominally
required crystal load capacitance. Because load
capacitance can only be increased in this trimming process,
it is important to keep stray capacitance to a minimum by
using very short PCB traces (and no vias) between the
crystal and device. Crystal capacitors, if needed, must be
connected from each of the pins X1 and X2 to ground.
The value (in pF) of these crystal caps should equal (C
L
-16
pF)*2. In this equation, C
L
= crystal load capacitance in pF.
Example: For a crystal with an 18 pF load capacitance, each
crystal capacitor would be 4 pF [(18-16) x 2] = 4.
ICLK/X1
VDD
GND
27M
CLK
OE
GND
X21
2
3
4
8
7
6
5
Pin
Number
Pin
Name
Pin
Type
Pin Description
1 ICLK/X1 XI Crystal connection. Connect to a 27 MHz fundamental crystal or clock.
2 VDD Power Connect to +3.3 V.
3 GND Power Connect to ground.
4 CLK Output 74.17582418 MHz.
5 GND Power Connect to ground.
6 OE Input Output enable. Tri-states CLK output when low. Internal pull-up to VDD.
7 27M Output 27 MHz buffered clock or crystal oscillator output.
8 X2 XO Crystal connection. Connect to a 27 MHz crystal, or leave unconnected
for clock input.
