LM3503ITL-25EV

User's Guide SNVA127A – July 2006 – Revised April 2013 AN-1407 LM3502/03 Evaluation Board 1 General Description The LM3502/03 evaluation board is a working demonstration of a step up DC-DC converter. The LM3502/03 is a white LED driver for lighting applications. The LM3502/03 contains two LED strings designed for dual displays with independence EN pins. The LM3502 LED current can be adjusted with a PWM signal while the LM3503 LED current can be adjusted with a DC voltage or RC filtered pulse-widthmodulated (PWM) signal at the Cntrl pin. The LM3502/03 can drive up to 10 white LEDs. Both devices feature internal over-voltage protection (OVP) and under-voltage protection (UVP). For evaluation purpose, the evaluation board is assembled in DSBGA package for 25V version (LM3503ITL) and 44V version (LM3502ITL). The LM3502/03 are also available in 16-WQFN package. For further information on boost converter topology, device electrical characteristics, and component selection, see the LM3502 Step-Up Converter for White LED Applications Data Sheet (SNVS339) and the LM3503 Dual-Display Constant Current LED Driver with Analog Brightness Control Data Sheet (SNVS329). 2 Operating Conditions • • • • • VIN range: 2.5V ≤ VIN ≤ 5.5V OVP options: 16V, 25V, 35V & 44V 10 Bump DSBGA or 16 Pin WQFN package Ambient temperature (TA) range: -40C to +85C Junction temperature (TJ) range: -40C to +125C All trademarks are the property of their respective owners. SNVA127A – July 2006 – Revised April 2013 Submit Documentation Feedback AN-1407 LM3502/03 Evaluation Board Copyright © 2006–2013, Texas Instruments Incorporated 1 Typical Application 3 www.ti.com Typical Application L 22 μH D MAIN: 2 to 5 LEDs Sw CIN + VSUPPLY VOUT1 VIN 4.7 μF VOUT2 Cntrl COUT - LM3502-44 En1 1 μF Fb En2 AGND PGND SUB: 2 to 5 LEDs Logic Voltage Signal Inputs R1 Figure 1. Typical Application Circuit LM3502 2 AN-1407 LM3502/03 Evaluation Board Copyright © 2006–2013, Texas Instruments Incorporated SNVA127A – July 2006 – Revised April 2013 Submit Documentation Feedback PWM Dimming www.ti.com L 22 μH D MAIN: 2 to 3 LEDs Sw VOUT1 VIN + CIN - VSUPPLY 4.7 μF VOUT2 Cntrl LM3503-25 En1 COUT 1 μF Fb En2 AGND DC Voltage Signal Input PGND SUB: 2 to 3 LEDs Logic Signal Inputs R1 Figure 2. Typical Application Circuit for LM3503 4 PWM Dimming If PWM dimming is desired to control the brightness of the LED string, care must be taken to balance the tradeoffs between audible noise and brigthness control. For best PWM duty cycle vs current linearity, the recommended PWM frequency should be between 200Hz to 500Hz for the LM3502. Similarly if PWM dimming is desired to control the brightness, a RC filter is necessary at the control pin for the LM3503 (Figure 3). To select the PWM frequency, use Equation 1 and Equation 2. FPWM > 10 * FRC (1) 1 FRC = 2*S*R*C (2) FPWM: PWM Singal Frequency FRC: RC Filter Bandwidth Cutoff Frequency R: Chosen Filter Resistor C: Chosen Filter Capacitor SNVA127A – July 2006 – Revised April 2013 Submit Documentation Feedback AN-1407 LM3502/03 Evaluation Board Copyright © 2006–2013, Texas Instruments Incorporated 3 LED Current Setting www.ti.com PWM Signal Sw VOUT1 VIN X R Y C Cntrl VOUT2 LM3503 En1 Fb En2 AGND PGND R1 Figure 3. Typical Circuit for PWM Dimming (LM3503) 5 LED Current Setting LEDcurrent is set using Equation 3 for LM3502/LM3503: ILED = VFb (3) R1 If analog control is used for brightness control in the LM3503, the relationship between VFB and VCNTRL can be determined by using Equation 4: VFB = (0.156) * (VCntrl) (4) For LM3502, the typical VFB is 0.25V to solve for ILED, or by rearranging ILED equation to solve for R1 . 4 AN-1407 LM3502/03 Evaluation Board Copyright © 2006–2013, Texas Instruments Incorporated SNVA127A – July 2006 – Revised April 2013 Submit Documentation Feedback Connection Diagram and Package Mark Information www.ti.com 6 Connection Diagram and Package Mark Information A2 A1 4 3 2 1 A3 B1 B3 C1 C3 D1 D3 5 16 6 15 7 14 8 13 9 10 11 12 D2 Figure 4. 10 Bump DSBGA Package SNVA127A – July 2006 – Revised April 2013 Submit Documentation Feedback Figure 5. 16-Thin WQFN (RGH0016A) AN-1407 LM3502/03 Evaluation Board Copyright © 2006–2013, Texas Instruments Incorporated 5 Connection Diagram and Package Mark Information www.ti.com Table 1. Pin Descriptions 6 Bump No WQFN Pin No Name A1 9 Cntrl Description B1 7 Fb C1 6 VOUT2 Drain Connections of the NMOS and PMOS Field Transistor (FET) Switches. Connect 100nF at VOUT2 node if VOUT2 is not used D1 4 VOUT1 Over-Voltage Protection (OVP) and source connection of the PMOS FET switch LED Current Control Connection Feeback Voltage Connection ( 0.2V < VCNTRL < 3.5V ) D2 2 and 3 SW D3 15 and 16 Pgnd Drain Connection of Power NMOS Switch Power Ground Connection C3 14 Agnd Analog Ground Connection B3 13 VIN Input Voltage Connection A3 12 En1 NMOS FET Switch Control Connection A2 10 En2 PMOS FET Switch Control Connection 1 NC No connect 5 NC No connect 8 NC No connect 11 NC No connect DAP DAP Die Attache Pad (DAP), to be soldered to the printed circuit board's ground plane for enhanced thermal dissipation AN-1407 LM3502/03 Evaluation Board Copyright © 2006–2013, Texas Instruments Incorporated SNVA127A – July 2006 – Revised April 2013 Submit Documentation Feedback Printed Circuit Board (PCB) Layout www.ti.com 7 Printed Circuit Board (PCB) Layout Figure 6. Top Silk Screen Figure 7. Bottom Silk Screen Figure 8. Top Traces Figure 9. Bottom Traces SNVA127A – July 2006 – Revised April 2013 Submit Documentation Feedback AN-1407 LM3502/03 Evaluation Board Copyright © 2006–2013, Texas Instruments Incorporated 7 Printed Circuit Board (PCB) Layout www.ti.com Figure 10. Top Pads Figure 11. Bottom Pads Table 2. Bill of Materials (BOM) for LM3502ITL and LM3503ITL Device Description Manufacture No LM3502 44V version (Drive up to 10 LEDs) Texas Instruments LM3503 25V Version ( Drive up to 6 LEDs) Texas Instruments CIN 4.7µF, 16V (3216X7R1C475K) TDK COUT 1µF, 50V (3216X7R1H105K) TDK R1 CRCW060328R0F (28 ohms) Vishay DIODE SS16 Vishay WHITE LED LTW67C Osram INDUCTOR DO1608C-223C (22µH) Coilcraft Test pins: VOUT, SW, VIN, FB, CNTRL, EN1, EN2 and GND Turret 0.09 inches 8 AN-1407 LM3502/03 Evaluation Board Copyright © 2006–2013, Texas Instruments Incorporated SNVA127A – July 2006 – Revised April 2013 Submit Documentation Feedback 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. 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