LM3485LEDEVAL

User's Guide SNVA120B – September 2005 – Revised April 2013 AN-1392 LM3485 LED Demo Board 1 Introduction The LM3485 LED driver board is a buck regulator derived controlled current source designed to drive high power, high brightness LEDs (HBLEDs) such as the Luxeon® Emitter at dissipations of 1W to 5W. The board can accept an input voltage ranging from 5 V to 30 V and can control the output current delivered to series and/or parallel arrays of HBLEDs as long as the forward voltage of all LEDs in series is less than (0.9 x VIN). The accuracy of the output current is ±10%. 2 Setting the LED Current The forward current IF delivered to the LED array is set by the program jumper, P2. If no jumper is installed, the LM3485 will default to the lowest current setting, 350 mA. Installing a jumper as shown in Figure 1 will change the current regulation point to 700 mA, 100 mA, or 1400 mA, respectively. 350 mA 700 mA 1000 mA 1400 mA Figure 1. Current Settings of P2 3 PWM Dimming Diode D2 provides an input for a pulse width modulation signal for dimming of the LED array. In order to fully enable and disable the LM3485 the PWM signal should have a maximum logic low level of 1.0 V, a minimum logic high level of 2.0 V, and minimum low and high periods of 40 µs. For example, at 100Hz, the minimum and maximum duty cycles to which the LM3485 can respond are 0.4% and 99.6%, respectively. At 1 kHz, the minimum and maximum duty cycles are 4% and 96%, respectively. The logic of the PWM is inverted, hence the LM3485 will deliver regulated output current when the voltage at the PWM IN terminal is low, and the current output is disabled when the voltage at the PWM IN terminal is high. Connecting a constant logic high to the PWM IN will disable the output. Luxeon is a registered trademark of Philips Lumileds Lighting Company in the United States and other countries. All other trademarks are the property of their respective owners. SNVA120B – September 2005 – Revised April 2013 Submit Documentation Feedback Copyright © 2005–2013, Texas Instruments Incorporated AN-1392 LM3485 LED Demo Board 1 Output Open Circuit 4 www.ti.com Output Open Circuit With PWM IN floating or connected to logic low, the LM3485 will begin to operate as soon as is has an input of at least 5 V. In the case that the input is powered but no LED array is connected the output voltage will rise to equal the input voltage. The output of the circuit is rated to 30 V and will not suffer damage, however care should be taken not to connect an LED array if the output voltage is higher than the target forward voltage of the LED array in steady state. 5 Typical Application Circuit VIN = 5-30V U1 VIN ISENSE CIN GND PGATE Q1 RCL LM3485 L1 P1 CCL To LED Anode D1 NC CO PWR GND RESR FB C535676 Connector VIN ADJ CF CFF RFF D2 U2 + - To LED Cathode LM321 RSET R350 PWM IN R700 P2 Ri R1 R1.4 Figure 2. Circuit Schematic 2 AN-1392 LM3485 LED Demo Board SNVA120B – September 2005 – Revised April 2013 Submit Documentation Feedback Copyright © 2005–2013, Texas Instruments Incorporated Typical Application Circuit www.ti.com Table 1. Bill of Materials ID Part Number Type Size U1 LM3485 Hysteretic Controller VSSOP-8 U2 LM321 Op-amp SOT23-5 Parameters Qty Vendor 1 TI 1MHz 1 TI L1 SLF7045T-6R8M1R7 Inductor 7.0x7.0 x4.5mm 6.8 µH, 1.7A 1 TDK Q1 Si3483DV PFET SuperSOT-6 -30 V, 5A 1 Vishay D1 SS24 Schottky Diode DO-214A, (SMB) 40 V, 2A 1 Vishay D2 MBR0520 Schottky Diode SOD-123 20 V, 0.5A 1 Vishay Cff VJ0805Y102KXXAT Capacitor 0805 1 nF, 10% 1 Vishay Cf C2012X7R1H104M Capacitor 0805 100 nF, 50 V 1 TDK Vishay Ccl VJ0805A101KXXAT Capacitor 0805 100 pF, 10% 1 Cin, Co C3216X7R1H105M Capacitor 1206 1 µF 50 V 2 TDK Rff CRCW08051002F Resistor 0805 10 kΩ, 1% 1 Vishay Resr CRCW08051R00F Resistor 0805 1 Ω 1% 1 Vishay Rcl CRCW08052552F Resistor 0805 25.5 kΩ 1% 1 Vishay Rset CRCW1206R500J Resistor 1206 0.5 Ω 5% 1 Vishay Ri CRCW08051002F Resistor 0805 10 kΩ 1% 1 Vishay R350 CRCW08056192F Resistor 0805 61.9 kΩ 1% 1 Vishay R700 CRCW08054422F Resistor 0805 44.2 kΩ 1% 1 Vishay R1 CRCW08051962F Resistor 0805 19.6 kΩ 1% 1 Vishay R1.4 CRCW08059091F Resistor 0805 9.09 kΩ 1% 1 Vishay P1 535676-5 Connector Custom 6 Pins 1 Tyco/AMP Connector Custom 4 AMP P2 SNVA120B – September 2005 – Revised April 2013 Submit Documentation Feedback Copyright © 2005–2013, Texas Instruments Incorporated AN-1392 LM3485 LED Demo Board 3 PCB Layout Diagram(s) 6 PCB Layout Diagram(s) 4 AN-1392 LM3485 LED Demo Board www.ti.com SNVA120B – September 2005 – Revised April 2013 Submit Documentation Feedback Copyright © 2005–2013, Texas Instruments Incorporated IMPORTANT NOTICE Texas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, enhancements, improvements and other changes to its semiconductor products and services per JESD46, latest issue, and to discontinue any product or service per JESD48, latest issue. Buyers should obtain the latest relevant information before placing orders and should verify that such information is current and complete. All semiconductor products (also referred to herein as “components”) are sold subject to TI’s terms and conditions of sale supplied at the time of order acknowledgment. TI warrants performance of its components to the specifications applicable at the time of sale, in accordance with the warranty in TI’s terms and conditions of sale of semiconductor products. Testing and other quality control techniques are used to the extent TI deems necessary to support this warranty. Except where mandated by applicable law, testing of all parameters of each component is not necessarily performed. TI assumes no liability for applications assistance or the design of Buyers’ products. Buyers are responsible for their products and applications using TI components. To minimize the risks associated with Buyers’ products and applications, Buyers should provide adequate design and operating safeguards. TI does not warrant or represent that any license, either express or implied, is granted under any patent right, copyright, mask work right, or other intellectual property right relating to any combination, machine, or process in which TI components or services are used. Information published by TI regarding third-party products or services does not constitute a license to use such products or services or a warranty or endorsement thereof. Use of such information may require a license from a third party under the patents or other intellectual property of the third party, or a license from TI under the patents or other intellectual property of TI. Reproduction of significant portions of TI information in TI data books or data sheets is permissible only if reproduction is without alteration and is accompanied by all associated warranties, conditions, limitations, and notices. TI is not responsible or liable for such altered documentation. Information of third parties may be subject to additional restrictions. Resale of TI components or services with statements different from or beyond the parameters stated by TI for that component or service voids all express and any implied warranties for the associated TI component or service and is an unfair and deceptive business practice. TI is not responsible or liable for any such statements. Buyer acknowledges and agrees that it is solely responsible for compliance with all legal, regulatory and safety-related requirements concerning its products, and any use of TI components in its applications, notwithstanding any applications-related information or support that may be provided by TI. Buyer represents and agrees that it has all the necessary expertise to create and implement safeguards which anticipate dangerous consequences of failures, monitor failures and their consequences, lessen the likelihood of failures that might cause harm and take appropriate remedial actions. Buyer will fully indemnify TI and its representatives against any damages arising out of the use of any TI components in safety-critical applications. In some cases, TI components may be promoted specifically to facilitate safety-related applications. With such components, TI’s goal is to help enable customers to design and create their own end-product solutions that meet applicable functional safety standards and requirements. Nonetheless, such components are subject to these terms. No TI components are authorized for use in FDA Class III (or similar life-critical medical equipment) unless authorized officers of the parties have executed a special agreement specifically governing such use. Only those TI components which TI has specifically designated as military grade or “enhanced plastic” are designed and intended for use in military/aerospace applications or environments. Buyer acknowledges and agrees that any military or aerospace use of TI components which have not been so designated is solely at the Buyer's risk, and that Buyer is solely responsible for compliance with all legal and regulatory requirements in connection with such use. TI has specifically designated certain components as meeting ISO/TS16949 requirements, mainly for automotive use. In any case of use of non-designated products, TI will not be responsible for any failure to meet ISO/TS16949. Products Applications Audio www.ti.com/audio Automotive and Transportation www.ti.com/automotive Amplifiers amplifier.ti.com Communications and Telecom www.ti.com/communications Data Converters dataconverter.ti.com Computers and Peripherals www.ti.com/computers DLP® Products www.dlp.com Consumer Electronics www.ti.com/consumer-apps DSP dsp.ti.com Energy and Lighting www.ti.com/energy Clocks and Timers www.ti.com/clocks Industrial www.ti.com/industrial Interface interface.ti.com Medical www.ti.com/medical Logic logic.ti.com Security www.ti.com/security Power Mgmt power.ti.com Space, Avionics and Defense www.ti.com/space-avionics-defense Microcontrollers microcontroller.ti.com Video and Imaging www.ti.com/video RFID www.ti-rfid.com OMAP Applications Processors www.ti.com/omap TI E2E Community e2e.ti.com Wireless Connectivity www.ti.com/wirelessconnectivity Mailing Address: Texas Instruments, Post Office Box 655303, Dallas, Texas 75265 Copyright © 2013, Texas Instruments Incorporated