ICS1572-101 Pinout

ICS1572-301 Pinout

CRYSTAL

OSCILLATOR

/ R

PHASE-

FREQUENCY

DETECTOR

CHARGE

PUMP

LOOP

FILTER

VCO

PRESCALER

/ A

/ M

MUX

MUX

/ 2

/ 4

/ N1

MUX

DRIVER

DIFF.

OUTPUT

DRIVER

/ N2

PROGRAMMING

INTERFACE

CLK+

CLK

−

LOAD

LD/N2

XTAL1

XTAL2

FEEDBACK DIVIDER

EXTFBK

BLANK

(-301 only)







N.C.

1

20

N.C.

AD0

2

19

AD1

XTAL1

3

18

AD2

XTAL2

4

17

VDD

STROBE

5

16

VDD

VSS

6

15

VDDO

VSS

7

14

IPRG

LOAD

8

13

CLK+

LD/N2

9

12

CLK-

N.C.

10

11

N.C.

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

User Programmable Differential Output Graphics Clock Generator

ICS1572

Figure 1

ICS1572RevC093094

RAMDAC is a trademark of Brooktree Corporation.

Integrated

Circuit

Systems, Inc.

N.C.

1

20

N.C.

AD0

2

19

AD1

XTAL1

3

18

AD2

XTAL2

4

17

VDD

STROBE

5

16

VDD

VSS

6

15

VDDO

VSS

7

14

IPRG

LOAD

8

13

CLK+

LD/N2

9

12

CLK-

N.C.

10

11

N.C.