ASM3P2854C
Custom Clock Generator for
Fax System
©2010 SCILLC. All rights reserved. Pub
lication Order Number:
OCTOBER 2010 – Rev. 1.1 ASM3P2854/D
Features
• Generates Custom Clocks for FAX system from an
in
expensive 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
Product Description
ASM3P2854C is a part of the two chip custom clock
gen
erator solution for NEC FAX system. Together with
ASM3P2855D, ASM3P2854C 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 selectable through two Select pins
S1 and S2. The accuracy of the synthesized
programmable clocks is within ±18ppm. The custom clock
generator works is with a Supply Voltage for 3.3V. The
device is available in a 16L TSSOP Green package, over
0°C to +70°C temperature range. The output Clocks h ave
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
