
MDS 376 C
3
Revision 051001
Integrated Circuit Systems, Inc. 525 Race Street,San Jose,CA,95126 (408) 295-9800 tel www.icst.com
ICS376
Quad PLL with VCXO Quick Turn Clock Synthesizer
External Components / Crystal Selection
The ICS376 requires two 0.01F decoupling capacitors to be connected between VDD and GND pairs. It is recommended that
these be placed between VDD and GND pairs on pins 5 and 6, and another between pins 16 and 15. These must be connected
close to the ICS376 to minimize lead inductance. No external power supply filtering is required for this device. A 33
series
terminating resistor can be used next to each CLK pin. The input crystal must be connected as close to the chip as possible.
The input crystal should be a parallel mode, pullable, AT cut with 14 pF load capacitance. See previous page for crystal
specifications. Consult ICS for recommended suppliers. IMPORTANT - read application note MAN05 before laying out the PCB.
Frequency Select Table
The ICS376 can be configured so that one PLL provides up to 8 frequency selections. For example, CPU frequencies of 66.7
MHz, 100.0 MHz, 133.3 MHz, and 166.7 MHz could be included. This information should be indicated on the Order Form when
the ICS376 is initially defined.
Device Configuration
The ICS376 QTClock provides the facility for up to 8 clock outputs. The outputs are derived from either the reference input or
from one of the 4 PLLs. All chip functions are controlled from an OTP ROM which has 3 input control lines (S2, S1, S0), giving a
total of 8 address locations. Each address location gives control of the following:
1) Each output can be turned off individually.
2) The internal dividers for each PLL are controlled to generate any required frequency.
3) Each PLL can be turned off (powered down) individually.
4) The output divide and control logic can be configured to bring the appropriate clock to the correct pin.
5) Up to four low skew copies of the same clock can be enabled.
This chip architecture provides the user with unrivaled flexibility. For example, one of the input pins could be used to control the
power of the chip by shutting down PLLs and outputs when not used. A second could be used to change the output clock
frequencies.
The specification is complete when the ICS376 QTClock Order Form accompanies this data sheet. The order form lists the input
and CLK actual frequencies, as well as any other available options. This unique configuration is given a two character
alphanumeric programming code (ICS376-xx), which must be specified when referring to samples.
Crystal Specifications
Correlation (load) capacitance
14 pF
Initial accuracy
± 20 ppm maximum
Drift over temperature and aging
± 50 ppm maximum
C0/C1 ratio
250 maximum
ESR
35
maximum