AND8349-D ONSEMI | Alldatasheet

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battery voltage possible in automotive electrical systems. 24 V for several minutes in a double battery jump scenario.

  • CHMSL Arrays
  • Instrument Cluster Backlighting
  • Switch Cluster Backlighting and Tell−T ales (Icon Lighting)
  • Dome Lighting
  • Mirror Lights
  • Fog Lights
  • Convenience Lighting
  • RGB Ambient Lighting
  • Emergency Flashlight Each application requires specific attention to light output and optical design, LED circuit topology, driver current requirements, and thermal management . It is the intent of this article to concentrate on CHMSL LED circuit requirements, and to discuss thermal management as it applies to the driver circuitry. An innovative use of a new Patent Pending Discrete Technology (Constant Current Regulator – CCR) will be shown to have several distinct advantages for controlling the LED operating current compared to the common method of selecting a bias resistor to adjust the LED operating current. Figure 1 shows a typical I-V curve for the NSI45030T1G device. The CCR is a current regulator that offers outstanding regulation for LEDs and other applications requiring a low cost, stable current source. Unlike costly switching regulators, a CCR is relatively EMI free, does not require startup circuitry, and operates as a current source or sink. Current regulation can be achieved for Anode−Cathode voltages ranging from as little as 1.8 V . No external components are required to regulate the typical value of 30 mA. Since these are CCR sources, parallel arrangements allow for higher load current applications. (Figure 7) The CCR reduces the complexity of resistor biased designs for sensitive loads such as LED strings connected in series (Figure 4). Simply apply a voltage greater than V overhead to achieve an accurate regulated current.

Figure 1. CCR IV Characteristics

9 V to 16 V, the current changes in the LED which affects the

is calculated. Again, the intensity of the LED is affected. determine how many series LEDs it can drive. Figure 6. Typical Application Circuit (12 Vdc − 4.2 Vdc)/2.2 Vdc = 3 LEDs in series. Figure 7. Typical Application Circuit

Figure 11. Power Dissipation vs. Ambient fwd is the best benefit to CCR LED biasing. battery voltage in automotive electrical systems. SOD−123 and SOT−223 packages.

http://onsemi.com APPENDIX A SOD−123 devices are: NSI45020T1G, Steady State Ireg(SS) = 20 mA /C003615% NSI45025T1G, Steady State Ireg(SS) = 25 mA /C003615% NSI45030T1G, Steady State Ireg(SS) = 30 mA /C003615% NSI45020A T1G, Steady State Ireg(SS) = 20 mA /C003610% NSI45025A T1G, Steady State Ireg(SS) = 25 mA /C003610% NSI45030A T1G, Steady State Ireg(SS) = 30 mA /C003610% SOT−223 devices are: NSI45025ZT1G, Steady State Ireg(SS) = 25 mA /C003615% NSI45030ZT1G, Steady State Ireg(SS) = 30 mA /C003615% NSI45025AZT1G, Steady State Ireg(SS) = 25 mA /C003610% NSI45030AZT1G, Steady State Ireg(SS) = 30 mA /C003610% APPENDIX B Application Note Title AND8391/D Thermal Considerations for the ON Semiconductor Family of Discrete Constant Current Regulators (CCR) for Drivings LEDs in Automotive Applications AND8220/D How To Use Thermal Data Found in Data Sheets AND8222/D Predicting the Effect of Circuit Boards on Semiconductor Package Thermal Performance AND8223/D Predicting Thermal Runaway ON Semiconductor and are registered trademarks of Semiconductor Components Industries, LLC (SCILLC). SCILLC reserves the right to make changes without further notice to any products herein. SCILLC makes no warranty, representation or guarantee regarding the suitability of its products for any particular purpose, nor does SCILLC assume any liability arising out of the application or use of any product or circuit, and specifically disclaims any and all liability, including without limitation special, consequential or incidental damages. “Typical” parameters which may be provided in SCILLC data sheets and/or specifications can and do vary in different applications and actual performance may vary over time. All operating parameters, including “Typicals” must be validated for each customer application by customer’s technical experts. SCILLC does not convey any license under its patent rights nor the rights of others. SCILLC products are not designed, intended, or authorized for use as components in systems intended for surgical implant into the body, or other applications intended to support or sustain life, or for any other application in which the failure of the SCILLC product could create a situation where personal injury or death may occur. Should Buyer purchase or use SCILLC products for any such unintended or unauthorized application, Buyer shall indemnify and hold SCILLC and its officers, employees, subsidiaries, affiliates, and distributors harmless against all claims, costs, damages, and expenses, and reasonable attorney fees arising out of, direct ly or indirectly, any claim of personal injury or death associated with such unintended or unauthorized use, even if such claim alleges that SCILLC was negligent regarding the design or manufacture of the part. SCILLC is an Equal Opportunity/Affirmative Action Employer. This literature is subject to all applicable copyright laws and is not for resale in any manner. PUBLICATION ORDERING INFORMATION N. American Technical Support: 800−282−9855 Toll Free USA/Canada Europe, Middle East and Africa Technical Support: Phone: 421 33 790 2910 Japan Customer Focus Center Phone: 81−3−5773−3850 AND8349/D The products described herein (NSI45030T1G) has patents pending. LITERATURE FULFILLMENT: Literature Distribution Center for ON Semiconductor P.O. Box 5163, Denver, Colorado 80217 USA Phone: 303−675−2175 or 800−344−3860 Toll Free USA/Canada Fax: 303−675−2176 or 800−344−3867 Toll Free USA/Canada Email: orderlit@onsemi.com ON Semiconductor Website: www.onsemi.com Order Literature: http://www.onsemi.com/orderlit For additional information, please contact your local Sales Representative