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January 2004 rev 1.0
2.5V LCD Panel Reduction IC
Features
FCC approved method of EMI attenuation. Provides up to 15dB of EMI suppression. Generates a low EMI spread spectrum clock of the input frequency. Input frequency range: 30MHz to 75 MHz. Optimized for 32.5MHz, 54MHz, and 65MHz. Internal loop filter minimizes external components and board space. Selectable spread deviation. SSON# control pin for spread spectrum enable and disable options. Low cycle-to-cycle jitter. 2.5V or 3.3V operating voltage range. TTL or CMOS compatible outputs. Ultra-low power CMOS design. Supports most mobile graphic accelerator and LCD timing controller specifications. Available in 8-pin TSSOP.
L2042A
cost savings by reducing the number of circuit board layers ferrite beads, regulations. The L2042A uses the most efficient and optimized modulation profile approved by the FCC and is implemented in a proprietary all digital method. The L2042A 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'. shielding and other passive components that are traditionally required to pass EMI
Applications
The L2042A is targeted towards digital flat panel applications for Notebook PCs, Palm-size PCs, office automation equipment, and LCD monitors.
Product Description
The L2042A is a versatile spread spectrum frequency modulator designed specifically for digital falt panel applications. The L2042A reduces electromagnetic interference (EMI) at the clock source, allowing system wide reduction of EMI of down stream clock and data dependent signals. The L2042A allows significant system
Block Diagram
SR0 CP1 CP0 SSON#
VDD
Modulation CLKIN Frequency Divider Feedback Divider
PLL
Phase Detector
Loop Filter
VCO
Output Divider
MODOUT
VSS
Alliance Semiconductor 2575, Augustine Drive * Santa Clara, CA * Tel: 408.855.4900 * Fax: 408.855.4999 * www.alsc.com
Notice: The information in this document is subject to change without notice.
January 2004 rev 1.0
Pin Configuration
XIN /CLK CP0 CP1 VSS
1 2 8 7
L2042A
VDD SR0 ModOUT SSON#
L2042A
3 4 6 5
Pin Description Pin# 1 2 3 4 6 7 5 8 Pin Name CLKIN CP0 CP1 VSS SSON# ModOUT SR0 VDD Type I I I P I O I P Description External reference frequency input. Connect to an externally generated reference signal. Digital logic input used to select charge pump current. Refer Modulation Selection Table. This pin has an internal pull-up resistor. Digital logic input used to select charge pump current. Refer Modulation Selection Table. This pin has an internal pull-up resistor. Ground to entire chip. Connect to system ground. Digital logic input used to enable Spread Spectrum function (Active LOW). Spread Spectrum function enabled when LOW, disabled when HIGH. This pin has an internal pull-low resistor. Spread spectrum clock output. Digital logic input used to select Spreading Range Refer Modulation Selection Table. This pin has an internal pull-up resistor. Power supply for the entire chip (+2.5V or 3.3V)
Modulation Selection Table Spreading Range ( %) 32.5MHz 0 0 0 0 1 1 1 1 0 0 1 1 0 0 1 1 0 1 0 1 0 1 0 1 0.49 1.71 1.2 1.69 1.09 1.68 0.8 1.29 54MHz 0.92 1.48 0.92 1.48 0.71 1.14 0.4 0.62 65MHz 0.88 1.37 0.88 1.37 0.58 0.9 0.3 0.48 70MHz 0.87 1.32 0.84 1.33 0.42 0.73 0.25 0.37 (FIN/40) * 62.49 KHz
CP0
CP1
SR0
Modulation Rate
2.5V LCD Panel EMI Reduction IC
Notice: The information in this document is subject to change without notice.
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January 2004 rev 1.0
Spread Spectrum
L2042A
The Modulation Selection Table illustrates the 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, Pin1). Example: The L2042A is designed for high-resolution flat panel applications and is able to support panel frequencies from 30 to 75 MHz. For a 65MHz pixel clock frequency, a spreading selection of CP0=0 and CP1=1 and SR0=1 gives a percentage deviation of TBD%. Refer Modulation Selection Table. This results in frequency on ModOUT being swept from TBD to TBD MHz. This particular example (See figure below) given here is a common EMI reduction method for notebook LCD panel and has already been implemented by most of the leading OEM and mobile graphic accelerator manufacturers.
65 MHz from Graphics Accelerator
1
CLKIN CP0 CP1 VSS
VDD SR0 ModOUT
8
2
7
Modulated 65MHz signal with 1.5% deviation and modulation rate of 50.77KHz. This signal is connected back to the spread spectrum input pin (SSIN) of the graphics accelerator
0.1F VDD
3
6
4
SSON# 5
L2042A
Digital control for SS Enable or Disable
2.5V LCD Panel EMI Reduction IC
Notice: The information in this document is subject to change without notice.
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January 2004 rev 1.0
EMC Software Simulation
L2042A
By using Alliance's proprietary EMC simulation software - EMI-Lator(R), radiated system level EMI analysis can be made easier, allowing quantitative measure on the benefits of Alliance's EMI reduction products. The simulation engine of this EMC software has already been characterized to correlate with the electrical characteristics of Alliance EMI reduction ICs. The figure below is an illustration of this simulation result. Please visit our website at www.alsc.com for information on how to obtain a free copy and demonstration of EMI-Lator (R).
Simulation results From EMI-Lator(R)
2.5V LCD Panel EMI Reduction IC
Notice: The information in this document is subject to change without notice.
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January 2004 rev 1.0
L2042A
Absolute Maximum Ratings Symbol VDD, VIN TSTG TA Parameter Voltage on any pin with respect to GND Storage temperature Operating temperature Rating -0.5 to + 7.0 -65 to +125 Unit V C
0 to 70 C Note: These are stress ratings only and functional operation is not implied. Exposure to absolute maximum ratings for extended periods may affect device reliability.
DC Electrical Characteristics Symbol VIL VIH IIL IIH VOL VOH ICC IDD VDD tON ZOUT Input low voltage Input high voltage Input low current (pull-up resistors on inputs SR0, SR1, CP0 and CP1) Input high current (pull-down resistor on input SSON#) Output low voltage (VDD = 3.3V, IOL = 20mA) Output high voltage (VDD = 3.3V, IOH = 20mA) Dynamic supply current normal mode (2.5V, and 15pF loading) Static supply current standby mode Operating voltage Power up time (first locked clock cycle after power up) Clock output impedance Parameter Min GND - 0.3 2.0 2.5 tbd @ 30MHz 2.25 Typ 0.6 2.85 0.18 50 Max 0.8 VDD + 0.3 -35 35 0.4 tbd @70MHz 3.7 Unit V V A A V V mA mA V mS
2.5V LCD Panel EMI Reduction IC
Notice: The information in this document is subject to change without notice.
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AC Electrical Characteristics Symbol fIN fOUT tLH* tHL* tJC Input frequency Output frequency Output rise time (measured at 0.8V to 2.0V) Output fall time (measured at 2.0V to 0.8V) Jitter (cycle to cycle) Parameter Min 30 30 0.7 0.6 40
L2042A
Typ 0.9 0.8 50
Max 75 75 1.1 1.0 360 55
Unit MHz MHz ns ns ps %
tD Output duty cycle *tLH and tHL are measured into a capacitive load of 15pF
2.5V LCD Panel EMI Reduction IC
Notice: The information in this document is subject to change without notice.
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Package Information 8-Pin TSSOP
L2042A
H
E D A2 A e B A1 L C
Dimensions in inches Symbol A A1 A2 B C D E e H L Min 0.047 0.002 0.031 0.007 0.004 0.114 0.169 0.006 0.041 0.012 0.008 0.122 0.177 Max
Dimensions in millimeters Min Max 1.10 0.05 0.80 0.19 0.09 2.90 4.30 0.65 BSC 6.20 0.45 0 6.60 0.75 8 0.15 1.05 0.30 0.20 3.10 4.50
0.026 BSC 0.244 0.018 0 0.260 0.030 8
2.5V LCD Panel EMI Reduction IC
Notice: The information in this document is subject to change without notice.
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Ordering Codes Part Number L2042AF-08TT L2042AF-08TR Part Number Guide L 1 1. 2 3 4 5 2042A 2 Alliance Semiconductor Mixed Signal Part Number Lead Free Part Pin Count Package Type: a . TT: TSSOP in TUBE b . TR: TSSOP in TAPE AND REEL F 3 08 4 Marking L2042A L2042A Package type 8-PIN TSSOP, TUBE 8-PIN TSSOP, TAPE AND REEL
L2042A
Temperature 0C To 70C 0C To 70C
XX 5
. . . .
Licensed under US patent #5,488,627, #6,646,463 and #5,631,920.
2.5V LCD Panel EMI Reduction IC
Notice: The information in this document is subject to change without notice.
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January 2004 rev 1.0
L2042A
Alliance Semiconductor Corporation 2595, Augustine Drive, Santa Clara, CA 95054 Tel# 408-855-4900 Fax: 408-855-4999 www.alsc.com
Copyright (c) Alliance Semiconductor All Rights Reserved Preliminary Information Part Number: L2042A Document Version: v1.0
Note: This product utilizes US Patent # 6,646,463 Impedance Emulator Patent issued to Alliance Semiconductor, dated 11-11-2003
(c) Copyright 2003 Alliance Semiconductor Corporation. All rights reserved. Our three-point logo, our name and Intelliwatt are trademarks or registered trademarks of Alliance. All other brand and product names may be the trademarks of their respective companies. Alliance reserves the right to make changes to this document and its products at any time without notice. Alliance assumes no responsibility for any errors that may appear in this document. The data contained herein represents Alliance's best data and/or estimates at the time of issuance. Alliance reserves the right to change or correct this data at any time, without notice. If the product described herein is under development, significant changes to these specifications are possible. The information in this product data sheet is intended to be general descriptive information for potential customers and users, and is not intended to operate as, or provide, any guarantee or warrantee to any user or customer. Alliance does not assume any responsibility or liability arising out of the application or use of any product described herein, and disclaims any express or implied warranties related to the sale and/or use of Alliance products including liability or warranties related to fitness for a particular purpose, merchantability, or infringement of any intellectual property rights, except as express agreed to in Alliance's Terms and Conditions of Sale (which are available from Alliance). All sales of Alliance products are made exclusively according to Alliance's Terms and Conditions of Sale. The purchase of products from Alliance does not convey a license under any patent rights, copyrights; mask works rights, trademarks, or any other intellectual property rights of Alliance or third parties. Alliance does not authorize its products for use as critical components in life-supporting systems where a malfunction or failure may reasonably be expected to result in significant injury to the user, and the inclusion of Alliance products in such life-supporting systems implies that the manufacturer assumes all risk of such use and agrees to indemnify Alliance against all claims arising from such use.
2.5V LCD Panel EMI Reduction IC
Notice: The information in this document is subject to change without notice.
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