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Details, datasheet, quote on part number:P2040A
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Datasheet text preview:
December 2002
PulseC r e
P2040A
LCD Panel EMI Reduction IC Features
· · · · · · · · · FCC approved method of EMI attenuation Provides up to 20 dB of EMI suppression Generates a low EMI spread spectrum clock of the input frequency 30- to 110-MHz input frequency range Optimized for VGA, SVGA, and higher resolution XGA LCD panels Internal loop filter minimizes external components and board space Six selectable high spread ranges up to ± 2% Two selectable modulation rates Low cycle-to-cycle jitter SR0 SR1 MRA SSON# · · · · · · · · SSON# control pin for spread spectrum enable and disable options Wide operating range (3V) 16 mA output drives TTL or CMOS compatible outputs Low power CMOS design Supports most mobile graphic accelerator specifications Products available for automotive temperature range. (See the Spread Spectrum Range Selection tables.) Available in 8-pin SOIC and TSSOP
Block Diagram
VDD
CLKIN
Modulation Frequency divider Feedback divider Phase detector Loop filter
PLL
VCO
Output divider
ModOUT VSS
Product Description
The P2040A is a selectable spread spectrum frequency modulator designed specifically for digital flat panel applications. The P2040A reduces electromagnetic interference (EMI) at the clock source which provides system wide reduction of EMI of all clock dependent signals. The P2040A allows significant system cost savings by reducing the number of circuit board layers and shielding that are traditionally required to pass EMI regulations. The P2040A uses the most efficient and optimized modulation profile approved by the FCC and is implemented in a proprietary all-digital method. The P2040A 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 P2040A is targeted toward digital flat-panel applications for notebook PCs, palm-size PCs, office automation equipment, and LCD monitors.
Pin Diagram
CLKIN MRA SR1 VSS 1 2 3 4 8 7 6 5 VDD SR0 ModOUT SSON#
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Modulation Selection (Commercial)
MRA 0 0 0 0 1 1 1 1 SR1 0 0 1 1 0 0 1 1 SR0 0 1 0 1 0 1 0 1 Spreading range ± 1.125 ± 1.75 ± 0.75 ± 1.25 ± 1.25 ± 2.00 Reserved Reserved Modulation rate (Fin/40) * 34.72 KHz (Fin/40) * 34.72 KHz (Fin/40) * 34.72 KHz (Fin/40) * 34.72 KHz (Fin/40) * 20.83 KHz (Fin/40) * 20.83 KHz Reserved Reserved
Spread Range Selection at 50 MHz (Automotive)
MRA 0 0 0 0 1 1 1 1 SR1 0 0 1 1 0 0 1 1 SR0 0 1 0 1 0 1 0 1 Spreading range ± 1.25 ± 2.00 ± 1.00 ± 1.50 ± 1.25 ± 2.00 ± 1.25 ± 2.00 Modulation rate (Fin/40) * 34.72 KHz (Fin/40) * 34.72 KHz (Fin/40) * 34.72 KHz (Fin/40) * 34.72 KHz (Fin/40) * 20.83 KHz (Fin/40) * 20.83 KHz (Fin/40) * 20.83 KHz (Fin/40) * 20.83 KHz
Spread Range Selection at 70 MHz (Automotive)
MRA 0 0 0 0 1 1 1 1 SR1 0 0 1 1 0 0 1 1 SR0 0 1 0 1 0 1 0 1 Spreading range ± 1.00 ± 1.50 ± 0.70 ± 1.00 ± 1.15 ± 2.00 ± 1.15 ± 1.75 Modulation rate (Fin/40) * 34.72 KHz (Fin/40) * 34.72 KHz (Fin/40) * 34.72 KHz (Fin/40) * 34.72 KHz (Fin/40) * 20.83 KHz (Fin/40) * 20.83 KHz (Fin/40) * 20.83 KHz (Fin/40) * 20.83 KHz
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Pin Description
PIN # 1 2 3 4 5 6 7 8 Name CLKIN M RA S R1 VSS SSON# ModOUT S R0 V DD Type I I I P I O I P Description External reference frequency input. Connect to externally generated reference signal. Digital logic input used to select modulation rate. This pin has an internal pullup resistor. Digital logic input used to select spreading range. This pin has an internal pullup resistor. Ground connection. Connect to system ground. Digital logic input used to enable spread spectrum function (active low). Spread spectrum function enabled when low. This pin has an internal pull-low resistor. Spread spectrum clock output. Digital logic input used to select spreading range. This pin has an internal pullup resistor. Connect to +3.3 V.
Spread Spectrum Selection
The "Modulation Selection" table defines possible spread spectrum options. The optimal setting should minimize system EMI to the fullest without affecting system performance. The spreading is described as a percentage deviation of the center frequency. (Note: The center frequency is the frequency of the external reference input on CLKIN, pin 1.) For example, P2040A is designed for high resolution flat panel applications and is able to support an XGA (1024 X 768) flat panel operating at a 65 MHz (Fin) clock speed. A spreading selection of MRA = 0, SR1 = 1, and SR0 = 0 provides a percentage deviation of ±0.75% from Fin (see the "Modulation selection" table). This results in the frequency on ModOUT being swept from 64.51 to 65.49 MHz at a modulation rate of 56.24 KHz (see the "Modulation selection" table). The example in the following illustration is a common EMI reduction method for a notebook LCD panel and has already been implemented by most of the leading OEM and mobile graphic accelerator manufacturers.
Application Schematic for Mobile LCD Graphics Controllers
Modulated 65 MHz signal with ±0.75% deviation and modulation rate of 56.24 KHz. This signal is connected back to the spread spectrum input pin (SSIN) of the graphics accelerator. VDD
65 MHz from graphics accelerator
1 CLKIN 2 MRA 3 SR1
VDD 8 SR0 7 ModOUT 6
0.1uF
SSON# 5 4 VS S X2040A
Digital control for SS enable or disable
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