Related Manuals for Samsung S3F84A5
Summary of Contents for Samsung S3F84A5
- Page 1 APPLICATION NOTE S3F84A5 An LED Lighting System January 2010 Revision 0.00 Confidential Proprietary of Samsung Electronics Co., Ltd Copyright © 2010 Samsung Electronics, Inc. All Rights Reserved...
- Page 2 Samsung reserves the right to make changes in its products or product specifications with the intent to improve function or design at any time and without notice and is not required to update this documentation to reflect such changes.
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Page 3: Revision History
Revision History Revision No. Date Description Author(s) Jan. 20, 2010 - Initial draft Wei Ningning... -
Page 4: Table Of Contents
Overview of HPLED Lighting Control System ...7 1.1 Pin Assignment in S3F84P4 ...7 1.2 Key Features of S3F84P4...8 1.3 System Principle ...8 1.3.1 Buck Circuit...9 1.3.2 Summary ...9 1.3.3 Constant Current Control...10 Hardware Implementation ...11 2.1 System Diagram and Circuit ...11 2.2 Components Selection...12 2.2.1 Select the Inductance (L1) for the Requirement of Current Ripple ...12 2.2.2 Select the Capacitance (C2) for the Requirement of Voltage Ripple ...12... - Page 5 Figure Number Figure 1-1 S3F84P4 Pin Assignment...7 Figure 1-2 Simplified Buck Circuit ...9 Figure 1-3 Current on load ...9 Figure 1-4 HKP-D1W1 Forward Voltage, Forward Current, and Relative Luminous Flux...10 Figure 2-1 Control Circuit ...11 Figure 3-1 Software Implementation Diagram ...13 Figure 3-2 Way to change PWM duty cycle ...14 Figure 4-1...
- Page 6 Table Number Table 4-1 System validation of efficiency...16 Table 5-1 BOM list of Key Circuit ...17 List of Tables Title Page Number...
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Page 7: Overview Of Hpled Lighting Control System
(normal rated power) is greater than 1W. It can be driven at currents that vary from hundreds of mA to more than an ampere. LEDs can produce hundreds of lumens, and find extensive usage in lighting systems. This document presents a simple HPLED lighting control system implemented with Samsung’s 8-bit MCU S3F84P4. -
Page 8: Key Features Of S3F84P4
. It is only used when the power supply is higher than the forward . It is only used when the forward voltage is higher than the power . It can be used without considering the relationship of power Samsung Confidential... -
Page 9: Buck Circuit
SMPS can lead to current ripple. But it could be alleviated by increasing the PWM frequency or coil inductance value, or by adding extra filtering circuits. 1 OVERVIEW OF HPLED LIGHTING CONTROL SYSTEM Figure 1-2 Simplified Buck Circuit Figure 1-3 Current on load Samsung Confidential... -
Page 10: Constant Current Control
1-4, describing the luminous flux as a function of current is better than describing it as a function of voltage. Even a slight change of voltage might lead to significant current shift. Therefore, constant current control is used in HPLED applications. Samsung Confidential... -
Page 11: Hardware Implementation
Brightness can be obtained by changing the PWM duty cycle after comparing the actual sensing value and target forward current. This application uses two external interrupts (“ENINT” and “GPIO” as shown in Figure 2-1) as keys to control the turn-on/off and brightness. A normal LED indicates the current brightness as full or half brightness. Samsung Confidential... -
Page 12: Components Selection
0.56 ripple Therefore, 1% voltage ripple means The freewheeling diode should be a Schottky diode, as the system requires low turn-on voltage and fast switching. 7.084 Samsung Confidential 2 HARDWARE IMPLEMENTATION... -
Page 13: Software Implementation
PWMEX, refer to the S3F84P4 User’s Manual. change the PWM duty cycle. Initialization ADC sampling Decrease PWM Value > max? Increase PWM Vale < min? Figure 3-1 Software Implementation Diagram Samsung Confidential 3 SOFTWARE IMPLEMENTATION duty cycle duty cycle Figure 3-2 shows the right way to... -
Page 14: Figure 3-2 Way To Change Pwm Duty Cycle
. The overall cycle is still 12-bit to make the 12-bit 4096 0.512 . So Therefore, every change of the duty cycle will Samsung Confidential 3 SOFTWARE IMPLEMENTATION Start PWMEX>= 11111100B? PWMEX = 0 PWMDATA + =1... -
Page 15: System Validation
Figure 4-1 efficiency Based on the above formulas, Table 1 shows the values of Ips, Imcu, Vfd, Vs, and efficiency (%). Waveform for HPLED forward voltage and current Samsung Confidential 4 SYSTEM VALIDATION... - Page 16 3.82 3.85 3.60 87.68 81.6 87.03 82.5 2) 1.1 . Due to the same reason, the efficiency of BD2 is always better than that Samsung Confidential 4 SYSTEM VALIDATION 3.86 3.90 3.59 87.35 81.6 87.37 80.95 3.90 3.65 87.45...
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Page 17: Appendix
100 uH inductance HPLED 1W1 HPLED 5.2 APPENDIX 2: SOURCE CODE For more information, refer to Source_Code_LED_S3F84P4_V10. Table 5-1 BOM list of Key Circuit Description VISHAY IR TDK HangKe Samsung Confidential Manufacturer Part number WSR21R000FEA IRF9540 IN5819 VLF12060-101M1R0 5 APPENDIX...