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LM3464MHX

LM3464MHX

  • 厂商:

    NSC

  • 封装:

  • 描述:

    LM3464MHX - LED Driver with Dynamic Headroom Control and Thermal Control Interfaces - National Semic...

  • 数据手册
  • 价格&库存
LM3464MHX 数据手册
LM3464/LM3464A LED Driver with Dynamic Headroom Control and Thermal Control Interfaces November 18, 2010 LM3464/LM3464A LED Driver with Dynamic Headroom Control and Thermal Control Interfaces General Description The LM3464/64A is a 4-channel high voltage current regulator that provides a simple solution for LED lighting applications. The LM3464/64A provides four individual current regulator channels and works in conjunction with external Nchannel MOSFETs and sense resistors to give accurate driving current for every LED string. Additionally, the Dynamic Headroom Control (DHC) output can be interfaced to the external power supply to adjust the LED supply voltage to the lowest level that is adequate to maintain all the string currents in regulation, yielding the optimal overall efficiency. Digital PWM or analog voltage signals can be used to control the duty cycle of the all the channels. When analog control is used, the dimming frequency can be programmed via an external capacitor. A minimum duty cycle control is provided in the conditions that the analog dimming is configured as thermal feedback. Protection features include VIN under-voltage lock-out, LED open/short circuit and over-temperature fault signaling to the system controller. Features ■ Wide input voltage range ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ 12V-80V (LM3464) 12V–95V (LM3464A) Dynamic Headroom Control ensures maximum efficiency 4 output channels with individual current regulation High channel to channel accuracy Digital PWM/Analog dimming control interface Resistor programmable dimming frequency & minimum duty cycle (analog dimming mode) Direct interface to thermal sensor Fault detection Over temperature protection Thermal shutdown Under voltage lockout Thermal enhanced eTSSOP-28 package Applications ■ Streetlights ■ Solid State Lighting Solutions Typical Application 30115001 © 2010 National Semiconductor Corporation 301150 www.national.com LM3464/64A Connection Diagram 30115002 Ordering Information Order Number LM3464MH LM3464MHX LM3464AMH LM3464AMHX Exposed Pad TSSOP-28 MXA28A Package Type Exposed Pad TSSOP-28 NSC Package Drawing MXA28A Supplied As 73 Units per Anti-Static Tube 2500 Units on Tape and Reel 73 Units per Anti-Static Tube 2500 Units on Tape and Reel www.national.com 2 LM3464/64A Pin Descriptions Pin 1 Name SYNC Description Synchronization signal output for cascade operation (Master-Slave configuration) PWM dimming control Thermal sensor input Application Information Connect this pin to the DIM pin of other LM3464/64A to enable cascade operation (multiple device). This pin should leave open for single device operation. Apply logic level PWM signal to this pin controls the average brightness of the LED string. ( 80V/95V (LM3464/64A) APPLICATIONS WITH HIGH RAIL VOLTAGE The normal operation voltage of the LM3464 and LM3464A are rated to 80V and 95V respectively, applying voltage over the operation voltage limit to the LM3464/64A can damage the device permanently. In applications that the rail voltage is higher than the operation voltage limited of the device (80V for LM3464, 95V for LM3464A), voltage clamping circuits must be added externally to ensure the voltage limits of all the pins of the LM3464/64A are not violated. Figure 13 shows a typical application circuit with 150V peak rail voltage. In figure 13, Z1, Z2, Z3, Z4 and ZIN are zener diodes for clamping the DRx pin voltage and input voltage (VIN pin) of the LM3464/64A. The reverse voltage of the zener diodes must be below 80V for LM3464 and 95V for LM3464A. The resistors RDR1, RDR2, RDR3, RDR4 and RIN are resistors for absorbing the voltage difference between the clamping voltage of the zener diodes and the rail voltage. Calculating the Values of Zx and RDRx: The resistance of the RDRx must be properly selected according to the reverse current of the zener diode and input current of the DRx pins of the LM3464/64A to secure the allowable Where VZ and IZ are the reverse voltage and current of the zener diode Zx respectively. pin voltages are not violated. For instant, the DRx pins are required to clamp at 75V and a 500mW/75V zener diode CMHZ5267B from Central Semiconductor is used. The reverse current of the CMHZ5267B is specified 1.7mA at 75V zener voltage. The maximum allowable reverse current is 6.67mA as the power rating of the CMHZ5276B is 500mW. Given that the input current of the DRx pins of the LM3464/64A at 100V is 63uA maximum, if the DRx pin voltage is below 100V the current flows into the DRx pin (IDRx) is below 63uA. In order to reserve operation margin for component variations, IDRx is assumed equal to 63uA in the following calculations. Because VRAIL(peak) is the possible highest voltage at the DRx pins, the maximum resistance of RDRx can be obtained following this equation: 17 www.national.com LM3464/64A For VRAIL(peak) = 150V, the maximum value of RDRx is: are 3mA and 700uA respectively, in order to ensure the voltage of the VIN pin is clamped close to 75V even when the LM3464/64A is disabled, a 1.5W/75V zener diode CMZ5946B from Central Semiconductor is used to ensure adequate conduction current for ZIN. The reverse current of the CMZ5946B is specified 5mA at 75V, so the allowable current flows through ZIN is in between 5mA to 20mA. The value of RIN is governed by the following equations: And the minimum value of RDRx is: Maximum value of RIN: Thus, the value of RDRx must be selected in the range: Minimum value of RIN: To minimize power dissipation on the zener diodes, a standard 42.2kΩ resistor can be used for the RDRx. Because the resistors, RDRx are used to absorb the power being introduced by the voltage difference between VRAIL and VZx, the maximum power dissipation on every RDRx equals to: So the value of RIN must be in the range: To minimize power dissipations on both the ZIN and RIN, a standard 9.31kΩ resistor can be selected for the RIN. Then the maximum power dissipation on RIN is: Thus, a standard 42.2kΩ resistor with 0.25W power rating (1206 package) and 1% tolerance can be used. Calculating the Values of ZIN and RIN: Similar to the requirements of selecting the Zx and RDRx, the voltage at the VIN pin of the LM3464/64A is clamped to 75V by a voltage clamping circuit consists of ZIN and RIN. Because the maximum operating and shut-down current (VEN < 2.1V) Thus, a standard 9.38kΩ resistor with 2512 package (1W) and 1% tolerance can be used. www.national.com 18 Additional Application Circuit LM3464/64A 19 30115022 FIGURE 14. Cascade Operation with Thermal Foldback Control www.national.com LM3464/64A Physical Dimensions inches (millimeters) unless otherwise noted 28-Lead eTSSOP Package NS Package Number MXA28A www.national.com 20 LM3464/64A Notes 21 www.national.com LM3464/LM3464A LED Driver with Dynamic Headroom Control and Thermal Control Interfaces Notes For more National Semiconductor product information and proven design tools, visit the following Web sites at: www.national.com Products Amplifiers Audio Clock and Timing Data Converters Interface LVDS Power Management Switching Regulators LDOs LED Lighting Voltage References PowerWise® Solutions Temperature Sensors PLL/VCO www.national.com/amplifiers www.national.com/audio www.national.com/timing www.national.com/adc www.national.com/interface www.national.com/lvds www.national.com/power www.national.com/switchers www.national.com/ldo www.national.com/led www.national.com/vref www.national.com/powerwise WEBENCH® Tools App Notes Reference Designs Samples Eval Boards Packaging Green Compliance Distributors Quality and Reliability Feedback/Support Design Made Easy Design Support www.national.com/webench www.national.com/appnotes www.national.com/refdesigns www.national.com/samples www.national.com/evalboards www.national.com/packaging www.national.com/quality/green www.national.com/contacts www.national.com/quality www.national.com/feedback www.national.com/easy www.national.com/solutions www.national.com/milaero www.national.com/solarmagic www.national.com/training Applications & Markets Mil/Aero PowerWise® Design University Serial Digital Interface (SDI) www.national.com/sdi www.national.com/wireless www.national.com/tempsensors SolarMagic™ THE CONTENTS OF THIS DOCUMENT ARE PROVIDED IN CONNECTION WITH NATIONAL SEMICONDUCTOR CORPORATION (“NATIONAL”) PRODUCTS. NATIONAL MAKES NO REPRESENTATIONS OR WARRANTIES WITH RESPECT TO THE ACCURACY OR COMPLETENESS OF THE CONTENTS OF THIS PUBLICATION AND RESERVES THE RIGHT TO MAKE CHANGES TO SPECIFICATIONS AND PRODUCT DESCRIPTIONS AT ANY TIME WITHOUT NOTICE. NO LICENSE, WHETHER EXPRESS, IMPLIED, ARISING BY ESTOPPEL OR OTHERWISE, TO ANY INTELLECTUAL PROPERTY RIGHTS IS GRANTED BY THIS DOCUMENT. TESTING AND OTHER QUALITY CONTROLS ARE USED TO THE EXTENT NATIONAL DEEMS NECESSARY TO SUPPORT NATIONAL’S PRODUCT WARRANTY. EXCEPT WHERE MANDATED BY GOVERNMENT REQUIREMENTS, TESTING OF ALL PARAMETERS OF EACH PRODUCT IS NOT NECESSARILY PERFORMED. NATIONAL ASSUMES NO LIABILITY FOR APPLICATIONS ASSISTANCE OR BUYER PRODUCT DESIGN. BUYERS ARE RESPONSIBLE FOR THEIR PRODUCTS AND APPLICATIONS USING NATIONAL COMPONENTS. PRIOR TO USING OR DISTRIBUTING ANY PRODUCTS THAT INCLUDE NATIONAL COMPONENTS, BUYERS SHOULD PROVIDE ADEQUATE DESIGN, TESTING AND OPERATING SAFEGUARDS. EXCEPT AS PROVIDED IN NATIONAL’S TERMS AND CONDITIONS OF SALE FOR SUCH PRODUCTS, NATIONAL ASSUMES NO LIABILITY WHATSOEVER, AND NATIONAL DISCLAIMS ANY EXPRESS OR IMPLIED WARRANTY RELATING TO THE SALE AND/OR USE OF NATIONAL PRODUCTS INCLUDING LIABILITY OR WARRANTIES RELATING TO FITNESS FOR A PARTICULAR PURPOSE, MERCHANTABILITY, OR INFRINGEMENT OF ANY PATENT, COPYRIGHT OR OTHER INTELLECTUAL PROPERTY RIGHT. LIFE SUPPORT POLICY NATIONAL’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS WITHOUT THE EXPRESS PRIOR WRITTEN APPROVAL OF THE CHIEF EXECUTIVE OFFICER AND GENERAL COUNSEL OF NATIONAL SEMICONDUCTOR CORPORATION. As used herein: Life support devices or systems are devices which (a) are intended for surgical implant into the body, or (b) support or sustain life and whose failure to perform when properly used in accordance with instructions for use provided in the labeling can be reasonably expected to result in a significant injury to the user. A critical component is any component in a life support device or system whose failure to perform can be reasonably expected to cause the failure of the life support device or system or to affect its safety or effectiveness. National Semiconductor and the National Semiconductor logo are registered trademarks of National Semiconductor Corporation. All other brand or product names may be trademarks or registered trademarks of their respective holders. Copyright© 2010 National Semiconductor Corporation For the most current product information visit us at www.national.com National Semiconductor Americas Technical Support Center Email: support@nsc.com Tel: 1-800-272-9959 www.national.com National Semiconductor Europe Technical Support Center Email: europe.support@nsc.com National Semiconductor Asia Pacific Technical Support Center Email: ap.support@nsc.com National Semiconductor Japan Technical Support Center Email: jpn.feedback@nsc.com
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