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DESCRIPTION
48-Channel LED Driver with PWM Generator and Serial Interface This demonstration circuit showcases the L T8500, a 48-channel LED driver with a PWM generator and serial interface. It operates from a 30V to 45V input power sup- ply and drives 48 channels of LED strings at 30mA and up to 32V each, although it can be adjusted for 50mA per string. The L T8500 drives 48 PWM channels that are tied directly to the PWM inputs of the three separate L T3595As. The L T3595A is a 16-channel step-down LED driver that can operate up to 45V input and up to 50mA per channel. The input to the L T8500 is a serial interface that can run up to 50MHz. The DC1552A has both an input and output connector and can be cascaded in a chain of two or more while being driven from a single serial interface. DC1552A is assembled as a solo 48-channel LED driver , but with a few simple modifications, it can be turned into one of the elements in a cascaded chain of DC1552As. The L T8500 is a pulse width modulation (PWM) genera- tor with 48 independent channels. Each channel has an individually adjustable 12-bit (4096-step) PWM register and a 6-bit (64-step) ±50% correction register . All controls are programmable via a simple serial data interface. Three banks of 16-channels each can be configured such that they operate 120 degrees out-of-phase with each other . The L T8500 features two diagnostic information flags: synchronization error and open LED. The flags are sent, with additional state information, on the serial data interface L, L T , L TC, L TM, Linear Technology and the Linear logo are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. during status read back. The 50MHz cascadable serial data interface includes buffering and skew-balancing, making the chip suitable for PWM intensive applications such as large screen LCD dynamic backlighting and mono-, multi- and full-color LED displays. The L T8500 is also ideally suited to control three L T3595A LED drivers. The L T3990 is a small 350mA step-down regulator with integrated power switch and diodes that operates up to 62V IN. Its 3mm × 3mm 16 pin MSOP and integrated components are a good housekeeping power supply to be used for 3.3V power on the L T8500 and it’s surrounding logic buffers. The L T8500, L T3595A, and L T3990 data sheets give complete descriptions of the parts, operation and applications infor- mation. The data sheets must be read in conjunction with this demo manual for DC1552A. The L T8500 and L T3595A are both assembled in 56 pin (5mm × 9mm × 0.75mm) QFN packages. Proper board layout is essential for both maximum thermal performance and signal noise immunity. See the layout considerations sections in the data sheets for more details. Design files for this circuit board are available at http://www.linear .com/demo
Figure 1. Typical Hardware Setup for Testing a Single DC1552A as a 48 Pixel LED Driver
48 Pixel LED panel
damage to the IC with input voltage ringing.
- Connect a panel of LEDs to the output connector P1 of
- Connect the serial data interface to connector P3.
- With power off, connect the PVIN power supply to the
PVIN and GND connection on P2.
- Turn the PVIN power supply on.
- Begin sending and receiving serial data from the serial
- Observe the LED string running at the programmed
LED current and the patterns on the LED panel. Table 1. Repeat the Quick-Start Procedure, but connect the PCB to the P3 input of the next PCB before power-up.
Table 1. Recommended Component Changes for Chaining Multiple DC1552As Together Figure 2. Hardware Setup for Testing the DC1552A in a Chain for Driving 144 Pixels of LEDs
ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER Required Circuit Components 1 7 C1-C7 CAP., X7R, 0.33μF , 50V , 10%, 0805 MURATA, GRM219R71H334KA88D 2 78 C8-C25, C32-C39, C41-C58, C60-C85, C87-C94 CAP., X7R, 0.47μF , 50V , 10%, 0805 MURATA, GRM21BR71H474KA88L 3 4 C26, C59, C86, C96 CAP ., X7R, 10μF , 10V , 10%, 0805 MURATA, GRM21BR71A106KE51L 4 1 C27 CAP., X5R, 0.22μF , 16V , 10%, 0603 TAIYO YUDEN, EMK107BJ224KA-T 5 1 C28 CAP., C0G, 22pF , 25V , 10%, 0402 AVX, 04023A220KAT2A 6 1 C29 CAP., X7R, 22μF , 6.3V , 20%, 0805 TAIYO YUDEN, JDK212BJ226MD-T 7 1 C95 CAP., X7R, 1μF , 10V , 10%, 0805 MURATA, GRM21BR71A105KA01L 8 1 C97 CAP., X7R, 1μF , 6.3V , 20%, 0603 AVX, 06036C105MAT2A 9 0 C98, C99 (OPT) CAP ., 0603 10 1 L49 IND. PWR, 10μH, L-LPO3310 COILCRAFT , LPO3310-103MLC 11 48 L1-L48 IND., 100μH, 1212 MURATA, LQH3NPN101MG0L 12 1 L50 IND., 33μH COILCRAFT , LPS6225-333ML 13 1 P1 HEADER, 2X50, 0.100" SAMTEC, TSW-150-07-L-D 14 1 P2 HEADER, 2X4, 0.100" SAMTEC, TSW-104-07-L-D 15 2 P3, P4 HEADER, 2X10, 0.100" SAMTEC, TSW-110-07-L-D 16 1 R1 RES., 4.99Ω, 1/8W , 1%, 0805 VISHAY, CRCW08054R99FNEA 17 1 R2 RES., 1.00M, 1/16W , 0402, 1% VISHAY, CRCW04021M00FKED 18 1 R3 RES., 576k, 1/16W , 1%, 0402 VISHAY, CRCW0402576KFKED 19 1 R5 RES., 374k, 1/16W , 0402, 1% VISHAY, CRCW0402374KFKED 20 3 R18, R39, R57 RES., 49.9k, 1/10W , 1%, 0603 VISHAY, CRCW060349K9FKEA 21 0 R61, R64, R68, R72 (OPT) RES., 0603 22 1 R19 RES., 33k, 1/10W , 1%, 0603 VISHAY, CRCW060333K0FKEA 23 4 R62, R65, R69, R71 RES., 0Ω, 1/10W , 0402 VISHAY, CRCW04020000Z0EA 24 1 R66 RES., 24.9k, 1/16W , 1%, 0402 VISHAY, CRCW040224K9FKED 25 3 U1-U3 IC., L T3595AEUHH, QFN56UHH-5X9 LINEAR TECH., L T3595AEUHH 26 1 U4 IC., L T8500EUHH, QFN56UHH-5X9 LINEAR TECH., L T8500EUHH 27 1 U5 IC., TinyLogic UHS Dual Buffer , SC70-6 FAIRCHILD SEMI., NC7WZ17P6X 28 0 U6, U7 (OPT) IC., TinyLogic UHS Dual Buffer , SC70-6 29 1 U8 IC., L TC1799CS5, SOT23-5 LINEAR TECH., L TC1799CS5 30 1 U9 IC., L T3990EMSE, MSE16 (1rl.+2 tubes) LINEAR TECH., L T3990EMSE 31 1 FAB, PRINTED CIRCUIT BOARD DEMO CIRCUIT 1552A 32 1 STENCIL TOP SIDE ONL Y STENCIL 1552A
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Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However , no responsibility is assumed for its use. Linear Technology Corporation makes no representa- tion that the interconnection of its circuits as described herein will not infringe on existing patent rights. SCHEMATIC DIAGRAM D D C C B B A A 39,19 /',% 6'2 3:0&. /',1(;7 6'2571 6'27+58 6&., 6', 3:0&./$67 6&.2 /',7+58 6&.2571 /',571 /',/$67 6'2/$67 6&.2/$676&.27+58 3:0 3:0 3:0 3:0 3:0 3:0 3:0 3:0 3:0 3:0 3:0 3:0 3:0 3:0 3:0 3:0 3:0 3:0 3:0 3:0 3:0 3:0 3:0 3:0 3:0 3:0 3:0 3:0 3:0 3:0 3:0 3:0 3:0 3:0 3:0 3:0 3:0 3:0 3:0 3:0 3:0 3:0 3:0 3:0 3:0 3:0 3:0 3:0 23(1/(' 9&& 9&& 9,1 9&& 9,1 9&&9&& 39,1 39,1 6,=( '$7( ,&12 5(9 6+((7 2) 7,7/( $33529$/6 3&%'(6 $33(1* TECHNOLOGY )D[ 0LOSLWDV&$ 3KRQH 0F&DUWK\\%OYG /7&&RQILGHQWLDO)RU&XVWRPHU8VH2QO\\ &86720(5127,&( 65(63216,%,/,7<72 6&+(0$7,& ZZZOLQHDUFRP .(,7+6 1$ '(02&,5&8,7$ /7(8++/7 $(8++ :HGQHVGD\\$XJXVW 6,=( '$7( ,&12 5(9 6+((7 2) 7,7/( $33529$/6 3&%'(6 $33(1* TECHNOLOGY )D[ 0LOSLWDV&$ 3KRQH 0F&DUWK\\%OYG /7&&RQILGHQWLDO)RU&XVWRPHU8VH2QO\\ &86720(5127,&( 65(63216,%,/,7<72 6&+(0$7,& ZZZOLQHDUFRP .(,7+6 1$ '(02&,5&8,7$ /7(8++/7 $(8++ :HGQHVGD\\$XJXVW 6,=( '$7( ,&12 5(9 6+((7 2) 7,7/( $33529$/6 3&%'(6 $33(1* TECHNOLOGY )D[ 0LOSLWDV&$ 3KRQH 0F&DUWK\\%OYG /7&&RQILGHQWLDO)RU&XVWRPHU8VH2QO\\ &86720(5127,&( 65(63216,%,/,7<72 6&+(0$7,& ZZZOLQHDUFRP .(,7+6 1$ '(02&,5&8,7$ /7(8++/7 $(8++ :HGQHVGD\\$XJXVW /7& /7& *1' 287 ',9 6(7 1&:=3; 237 1&:=3; 237 9&& *1' N N 237 237 237 237 76:/' 287 76:/' 287 1&:=3; 2378 1&:=3; 237 9&& *1' 1&:=3; 1&:=3; 9&& *1' 237 237 237 237 76:/' 76:/' /7(8++ /7(8++ 3:0 3:0 3:0 3:0 3:0 3:0 3:0 3:0 3:0 3:0 3:0 3:0 3:0 3:0 3:0 3:0 *1' 9&& /',%/$1. 3:0 3:0 3:0 3:0 3:0 3:0 3:0 3:0 3:0 3:0 3:0 3:0 3:0 3:0 3:0 3:0 3:0 3:0 3:0 3:0 3:0 3:0 3:0 3:0 3:0 3:0 3:0 3:0 3:0 3:0 3:0 3:0 23(1/(' 6'2 6&., 6&.2 3:0&. 6', 237 237 237 237 76:/' 76:/'
Linear Technology Corporation 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 ● FAX: (408) 434-0507 ● www.linear .com © LINEAR TECHNOLOGY CORPORATION 2011 LT 1211 • PRINTED IN USA DEMONSTRATION BOARD IMPORTANT NOTICE Linear Technology Corporation (L TC) provides the enclosed product(s) under the following AS IS conditions: This demonstration board (DEMO BOARD) kit being sold or provided by Linear Technology is intended for use for ENGINEERING DEVELOPMENT OR EVALUATION PURPOSES ONL Y and is not provided by L TC for commercial use. As such, the DEMO BOARD herein may not be complete in terms of required design-, marketing-, and/or manufacturing-related protective considerations, including but not limited to product safety measures typically found in finished commercial goods. As a prototype, this product does not fall within the scope of the European Union directive on electromagnetic compatibility and therefore may or may not meet the technical requirements of the directive, or other regulations. If this evaluation kit does not meet the specifications recited in the DEMO BOARD manual the kit may be returned within 30 days from the date of delivery for a full refund. THE FOREGOING WARRANTY IS THE EXCLUSIVE WARRANTY MADE BY THE SELLER TO BUYER AND IS IN LIEU OF ALL OTHER WARRANTIES, EXPRESSED, IMPLIED, OR STATUTORY, INCLUDING ANY WARRANTY OF MERCHANTABILITY OR FITNESS FOR ANY PARTICULAR PURPOSE. EXCEPT TO THE EXTENT OF THIS INDEMNITY, NEITHER PARTY SHALL BE LIABLE TO THE OTHER FOR ANY INDIRECT , SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES. The user assumes all responsibility and liability for proper and safe handling of the goods. Further , the user releases L TC from all claims arising from the handling or use of the goods. Due to the open construction of the product, it is the user’s responsibility to take any and all appropriate precautions with regard to electrostatic discharge. Also be aware that the products herein may not be regulatory compliant or agency certified (FCC, UL, CE, etc.). No License is granted under any patent right or other intellectual property whatsoever. L TC assumes no liability for applications assistance, customer product design, software performance, or infringement of patents or any other intellectual property rights of any kind. L TC currently services a variety of customers for products around the world, and therefore this transaction is not exclusive. Please read the DEMO BOARD manual prior to handling the product . Persons handling this product must have electronics training and observe good laboratory practice standards. Common sense is encouraged. This notice contains important safety information about temperatures and voltages. For further safety concerns, please contact a L TC applica- tion engineer . Mailing Address: Linear Technology 1630 McCarthy Blvd. Milpitas, CA 95035 Copyright © 2004, Linear Technology Corporation