ICS667-01 Datasheet, PDF (2/5 Pages) Integrated Circuit Systems – HDTV CLOCK SYNTHESIZER

ICS667-01
HDTV CLOCK SYNTHESIZER
Pin Assignment
ICLK/X1 1
VDD 2
GND 3
CLK 4
8 X2
7 27M
6 OE
5 GND
Pin Descriptions
Pin
Pin
Number Name
1
ICLK/X1
2
VDD
3
GND
4
CLK
5
GND
6
OE
7
27M
8
X2
Pin
Type
XI
Power
Power
Output
Power
Input
Output
XO
Pin Description
Crystal connection. Connect to a 27 MHz fundamental crystal or clock.
Connect to +3.3 V.
Connect to ground.
74.17582418 MHz.
Connect to ground.
Output enable. Tri-states CLK output when low. Internal pull-up to VDD.
27 MHz buffered clock or crystal oscillator output.
Crystal connection. Connect to a 27 MHz crystal, or leave unconnected
for clock input.
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.
MDS 667-01 C
2
Revision 031605
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