P1708C Datasheet, PDF (1/10 Pages) Alliance Semiconductor Corporation – Low Power Notebook LCD Panel EMI Reduction IC

June 2004
P1708C
rev 1.1
Low Power Notebook LCD Panel EMI Reduction IC
Features
ƒ FCC approved method of EMI attenuation.
ƒ Generates a low EMI spread spectrum clock of the
input frequency.
ƒ Optimized for frequency range from 50 to 110MHz.
ƒ Internal loop filter minimizes external components
and board space.
ƒ Four selectable spread ranges.
ƒ Low inherent cycle-to-cycle jitter.
ƒ 3.3V operating voltage range.
ƒ TTL or CMOS compatible inputs and outputs.
ƒ Ultra-low power CMOS design.
ƒ 8.46 mA @3.3V, 54MHz
ƒ 9.79 mA @3.3V, 65MHz
ƒ 12.06 mA @3.3V, 81MHz
ƒ 16.51 mA @3.3V, 108MHz
ƒ Supports notebook VGA and other LCD timing
controller applications.
ƒ Pinout compatible to ICS MK1708 and Cypress
CY25560.
ƒ SSON/SBM pin for Spread Spectrum On/Off and
Standby Mode controls.
ƒ Available in 8-pin SOIC and TSSOP.
Product Description
The P1708C is a versatile spread spectrum frequency
modulator designed specifically for input clock frequencies.
The P1708C reduces electromagnetic interference (EMI) at
the clock source, allowing system wide reduction of EMI of
down stream clock and data dependent signals. The
P1708C allows significant system cost savings by reducing
the number of circuit board layers ferrite beads, shielding
and other passive components that are traditionally
required to pass EMI regulations.
The P1708C modulates the output of a single PLL in order
to “spread” the bandwidth of a synthesized clock, and more
importantly, decreases the peak amplitudes of its
harmonics. This results in significantly lower system EMI
compared to the typical narrow band signal produced by
oscillators and most frequency generators. Lowering EMI
by increasing a signal’s bandwidth is called ‘spread
spectrum clock generation’.
The P1708C uses the most efficient and optimized
modulation profile approved by the FCC and is
implemented in a proprietary all digital method.
Applications
The P1708C is targeted towards notebook LCD displays,
and other displays using an LVDS interface, PC peripheral
devices, and embedded systems.
Block Diagram
SR0 SR1 ^SSON
VDD
CLKIN
Frequency
Divider
Feedback
Divider
Modulation
Phase
Detector
Loop
Filter
PLL
VCO
Output
Divider
ModOUT
VSS
Alliance Semiconductor
2575, Augustine Drive • Santa Clara, CA • Tel: [phone] • Fax: [phone] • www.alsc.com
Notice: The information in this document is subject to change without notice.