ICS1572 Datasheet, PDF (1/19 Pages) Integrated Circuit Systems – User Programmable Differential Output Graphics Clock Generator

Integrated
Circuit
Systems, Inc.
ICS1572
User Programmable Differential Output Graphics Clock Generator
Description
The ICS1572 is a high performance monolithic phase-locked
loop (PLL) frequency synthesizer. Utilizing ICS’s advanced
CMOS mixed-mode technology, the ICS1572 provides a low
cost solution for high-end video clock generation in worksta-
tions and high-end PC applications.
The ICS1572 has differential video clock outputs (CLK+ and
CLK-) that are compatible with industry standard video DACs.
Another clock output, LOAD, is provided whose frequency is
derived from the main clock by a programmable divider. An
additional clock output is available, LD/N2, which is derived
from the LOAD frequency and whose modulus may also be
programmed.
Operating frequencies are fully programmable with direct con-
trol provided for reference divider, pre-scaler, feedback divider
and post-scaler.
Reset of the pipeline delay on Brooktree RAMDACs may
be performed under register control. Outputs may also be set
to desired states to facilitate circuit board testing.
Features
• Supports high-resolution graphics - CLK output to
180 MHz
• ^{Eliminates need for multiple ECL output crystal oscillators}
• Fully programmable synthesizer capability - not just a
clock multiplier
• Available in 20-pin 300-mil wide body SOIC package
• Available in both parallel (101) and serial (301)
programming versions
• Circuit included for reset of Brooktree RAMDAC pipeline
delay
Applications
• Workstations
• AutoCad Accelerators
• High-end PC graphics systems
ICS1572-101 Pinout
XTAL1
XTAL2
CRYSTAL
OSCILLATOR
 EXTFBK _{(-301 only)}
 _BLANK

PROGRAMMING
INTERFACE
/R
PHASE-
FREQUENCY
DETECTOR
MUX
CHARGE
PUMP
LOOP
FILTER
VCO
PRESCALER
/M
/A
FEEDBACK DIVIDER
MUX
/2
/4
DIFF.
OUTPUT
/ N1
MUX
DRIVER
/ N2
DRIVER
N.C. 1
AD0 2
XTAL1 3
XTAL2 4
STROBE 5
VSS 6
VSS 7
LOAD 8
LD/N2 9
N.C. 10
20 N.C.
19 AD1
18 AD2
17 VDD
16 VDD
15 VDDO
14 IPRG
13 CLK+
12 CLK-
11 N.C.
CLK+
CLK−
LOAD
LD/N2
ICS1572-301 Pinout
N.C. 1
AD0 2
XTAL1 3
XTAL2 4
STROBE 5
VSS 6
VSS 7
LOAD 8
LD/N2 9
N.C. 10
20 N.C.
19 AD1
18 AD2
17 VDD
16 VDD
15 VDDO
14 IPRG
13 CLK+
12 CLK-
11 N.C.
Figure 1
ICS1572RevC093094
RAMDAC is a trademark of Brooktree Corporation.