August 2007

ASM3P2854B

rev 0.3

Notice: The information in this document is subject to change without notice.

PulseCore Semiconductor Corporation

1715 S. Bascom Ave Suite 200 Campbell, CA 95008

• Tel: 408-879-9077 • Fax: 408-879-9018

www.pulsecoresemi.com

Custom Clock Generator for Fax System

Features

•

Generates Custom Clocks for FAX system from

an inexpensive 24MHz Crystal

•

2x 66.66MHz low EMI (Spread Spectrum) clocks

for ASIC1 (System / DDR SDRAM)

•

1 x 48MHz for USB1.1 HOST

•

2 x 33.33MHz low EMI (Spread Spectrum)

clocks for System / DDR SDRAM of ASIC2 and

ASIC3

•

1x 25MHz low EMI (Spread Spectrum) clock for

LCD, Serial port, and buzzer of ASIC1

•

1x 12MHz for USB PHY (USB2.0)

•

1x Programmable clock for printer engine control

•

One of the four programmable clock outputs

selection through two Select Pins

•

Supply Voltage 3.3V +/- 0.3V

•

Available in 16L TSSOP, Green package

•

Commercial Temperature operation

Product Description

ASM3P2854B is a part of the two chip custom clock

generator solution for NEC FAX system. Together with

ASM3P2855A, ASM3P2854B realizes all the seventeen

clocks required by the various components and

subsystems of the FAX system. It uses an inexpensive

24MHz crystal as the input to generate two 66.66MHz low

EMI (spread spectrum) clocks used by ASIC1 for system

/ DDR SDRAM, two 33.33MHz low EMI (spread

spectrum) clocks used by ASIC2 and ASIC3 for system /

DDR SDRAM, a 25MHz low EMI (Spread Spectrum)

clock used by ASIC1 for LCD, Serial port, and buzzer, a

48MHz clock used by USB1.1 HOST, and a 12MHz clock

used by USB PHY (USB2.0). One of the four

Programmable

clock

(PCLK)

frequencies

of

24.00448MHz,

21.33732MHz,

21.19962MHz

and

20.40464MHz used for Printer Engine control is

selectable through

two Select pins S1 and S2. The

accuracy of the synthesized programmable clocks is

within +/- 18ppm. The custom clock generator works with

a Supply Voltage for 3.3V. The device is available in a

16L TSSOP Green package, in commercial temperature

range. The output Clocks have an accuracy of ±50ppm.

Block Diagram

2

2

PCLK

48MHz

PLL

Crystal

(24 MHz)

XIN / CLKIN

XOUT

66.6MHz SSCLK

PLL

PLL

33.3MHz SSCLK

25MHz SSCLK

12MHz

S1

S2

VDD

VDD_FOUT

GND

GND_FOUT