LM3410XBSTOVPEV/NOPB

User's Guide SNVA410A – April 2010 – Revised May 2013 AN-1996 LM3410X 190mA, LED Driver 6-Pin LLP Evaluation Board 1 Introduction This evaluation board showcases the LM3410X as a boost LED driver. It is designed to drive four, onboard LEDs (VOUT = 11.4 V) in series at an average LED current (ILED) of 190mA. The circuit can accept an input voltage of 3.3 V-5.5 V. The switching frequency of the LM3410X converter is 1.6MHz allowing the use of small surface mount inductors and chip capacitors. This evaluation board also features the PWM capability of the LM3410 by enabling the user to apply a periodic pulse signal to the DIM terminal of varying duty cycle. This is a 2-layer board using the bottom layer as a ground plane. A schematic and layout are shown below along with measured performance characteristics. A bill of materials is also provided that describes the parts used on this evaluation board. The above restrictions for the input voltage are valid only for the evaluation board as shipped with the evaluation board schematic shown in Figure 1. Operating Conditions: • VIN = 3.3 V to 5.5 V • VOUT ≊ VF x 4 + VFB ≊ 2.8 V x 4 + 0.190 V ≊ 11.4 V • ILED ≊ 190 mA L1 D1 J1 VIN LM3410 C1 R2 C3 D3 R5 DIMM 1 6 2 5 3 4 C2 D2 C4 LEDs R3 R1 R4 Figure 1. Schematic All trademarks are the property of their respective owners. SNVA410A – April 2010 – Revised May 2013 Submit Documentation Feedback AN-1996 LM3410X 190mA, LED Driver 6-Pin LLP Evaluation Board Copyright © 2010–2013, Texas Instruments Incorporated 1 Setting the LED Current www.ti.com Table 1. Pin Descriptions Pin Name Function 1 PGND Power ground pin. Place PGND and output capacitor GND close together. 2 VIN Supply voltage for power stage, and input supply voltage. 3 DIM Dimming & shutdown control input. Logic high enables operation. Duty Cycle from 0 to 100%. Do not allow this pin to float or be greater than VIN + 0.3 V. 4 FB Feedback pin. Connect FB to external resistor divider to set output voltage. 5 AGND 6 SW DAP GND Signal ground pin. Place the bottom resistor of the feedback network as close as possible to this pin & pin 4. Output switch. Connect to the inductor, output diode. Signal & Power ground. Connect to pin 1 and pin 5 on top layer. Place 4-6 vias from DAP to bottom layer GND plane. Table 2. Bill of Materials 2 Part ID Part Value Manufacturer Part Number U1 2.8A ISW LED Driver TI LM3410X C1, Input Cap 10µF, 6.3 V, X5R TDK C2012X5R0J106M C2, Output Cap 2.2µF, 25 V, X7R TDK C3225X7R1E225K C3, Input Cap Placeholder (not stuffed) - - C4, Output Cap 4.7µF, 25 V, X7R TDK C3225X7R1E475K D1, Catch Diode 0.4 Vf Schottky, 500mA ON Semiconductor MBR0530T1G D2 15 V Zener Diode Central Semiconductor CMHZ4702 D3 0.4 Vf Schottky, 500mA ON Semiconductor MBR0530T1G L1 3.3µH, 5.4A Coilcraft DO3316P-332 R1 1Ω, 1% Vishay CRCW12061R00FNEA R2 Placeholder (not stuffed) - - R3 100Ω, 1% Vishay CRCW0603100RFKEA R4 Placeholder (not stuffed) - - R5 6.8kΩ, 1% Vishay CRCW08056K80FKEA J1 Jumper Samtec TSW-102-07-T-S SH-J1 Jumper shunt Tyco Electronics 2-382811-1 LEDs 700mA, Vf ≊ 3.4 V Cree XPEWHT-L1-0000-008E5 Setting the LED Current The default forward current ILED delivered to the LED array is 190mA. To adjust this value, the current setting resistors R1 and R4 can be changed according to the following equation: ILED = (VFB)/(R1 || R4) The feedback voltage VFB is regulated at 0.190 V typically. The resistors R1 and R4 should be rated to handle the power dissipation of the LED current. 3 PWM Dimming The default set-up of the DIM terminal is to enable PWM dimming. If PWM dimming is not required, then the DIM pin can be tied to VIN through a resistor, R2, using the existing 0805 sized resistor footprint. This enables the LM3410 whenever VIN is applied and allows the set ILED current to flow through the LEDs continuously. A recommended value for R2 is 100kΩ. A periodic pulse signal at different frequencies and/or duty cycle can be applied to the evaluation board's DIM terminal for PWM dimming. The voltage measured at the DIM package lead must not be higher than 0.3 V above VIN for proper operation. Diode D3 and resistor R5 have been placed in the circuit to clamp the signal at the DIM lead to no greater than 0.3 V above VIN. Although not recommended, a PWM signal can therefore be applied to the evaluation board DIM terminal with a peak voltage greater than VIN. 2 AN-1996 LM3410X 190mA, LED Driver 6-Pin LLP Evaluation Board Copyright © 2010–2013, Texas Instruments Incorporated SNVA410A – April 2010 – Revised May 2013 Submit Documentation Feedback Over-Voltage Protection www.ti.com 4 Over-Voltage Protection The evaluation board includes over-voltage protection (OVP) circuitry, in the combination of zener diode D4 and resistor R3, to protect the LM3410 device in a situation where the output load is suddenly removed from the rest of the converter (i.e. an LED goes open). A header (J1) on the board allows the user to activate the OVP function by removing the associated jumper. The switching voltage at the SW pin will then be clamped to approximately the zener diode voltage of 18 V. Current will then flow through D4, R3 and sense resistor R1. This generates a voltage greater than 0.190 V at the FB pin that forces the LM3410’s internal switching power FET to turn off, thereby, preventing an over-voltage condition at the SW pin and damaging the LM3410. 5 Typical Performance Characteristics TA = +25°C, VOUT = 11.4 V, unless otherwise specified. 200 200 180 160 180 500 Hz 120 100 100 Hz 120 100 80 100 Hz 60 60 40 40 20 20 0 0 1 kHz 140 1 kHz ILED (mA) ILED (mA) 140 80 500 Hz 160 10 20 30 40 50 60 70 80 90 100 0 0 10 20 30 40 50 60 70 80 90 100 DUTY CYCLE (%) Figure 2. PWM Dimming, VIN = 3.3 V SNVA410A – April 2010 – Revised May 2013 Submit Documentation Feedback DUTY CYCLE (%) Figure 3. PWM Dimming, VIN = 5.5 V AN-1996 LM3410X 190mA, LED Driver 6-Pin LLP Evaluation Board Copyright © 2010–2013, Texas Instruments Incorporated 3 Typical Performance Characteristics www.ti.com 100 500 3 6.0 5.0 VDIM 4.0 2 400 2.0 1 90 300 1.0 0.00 -1.0 85 200 ILED -2.0 ILED (mA) 3.0 VDIM (V) EFFICIENCY (%) 95 -3.0 100 -4.0 3.5 4.0 4.5 5.0 -5.0 5.5 -6.0 0 INPUT VOLTAGE (V) Figure 4. Efficiency vs. Input Voltage, ILED = 190 mA 3 6.0 500 400 3.0 300 -1.0 200 ILED 2.0 1 VDIM (V) 1.0 0 0.0 ILED (mA) VDIM (V) 4.0 2 VDIM 300 1.0 0.00 -1.0 200 -2.0 -3.0 100 -4.0 -3.0 -4.0 -5.0 0 100.000µ 300.000µ 100 Ps/DIV 500.000µ Figure 6. 500Hz PWM Dimming (Rising Edge), 50% Duty Cycle, VIN = 3.3 V 4 500 6.0 3 400 VDIM 1 2.0 -6.0 -100.000µ 0 5.0 2 4.0 -2.0 0 0 1 ms/DIV Figure 5. 500Hz PWM Dimming, 50% Duty Cycle, VIN = 3.3 V 5.0 3.0 0 0 ILED (mA) 80 3.0 100 ILED -5.0 0 -6.0 -100.000µ 60.000µ 220.000µ 380.000µ 540.000µ 100 Ps/DIV Figure 7. 500Hz PWM Dimming (Falling Edge) 50% Duty Cycle, VIN = 3.3 V AN-1996 LM3410X 190mA, LED Driver 6-Pin LLP Evaluation Board Copyright © 2010–2013, Texas Instruments Incorporated SNVA410A – April 2010 – Revised May 2013 Submit Documentation Feedback Two Power Supply Design with 12 V > VPWR > 5.5 V www.ti.com 6 Two Power Supply Design with 12 V > VPWR > 5.5 V The evaluation board can be modified to allow the user to derive the power from an input supply that is larger than 5.5 V. In Figure 8, two separate supplies are needed. VIN must be between 3.3 V minimum to 5.5 V maximum, but VVPWR can be as great as 12 V. The recommended power-up sequence is VIN then VPWR. Power-down should be in the reverse order. L1 D1 J1 VPWR VIN C5 C1 R2 C3 D3 R5 DIMM LM3410 1 6 2 5 3 4 C2 D2 C4 LEDs R3 R1 R4 Figure 8. Two Power Supply Schematic Table 3. Bill of Materials (BOM) - Two Power Supply Design Part ID Part Value Manufacturer Part Number U1 2.8A ISW LED Driver TI LM3410X C1, VIN, Input Cap 10µF, 6.3 V, X5R TDK C2012X5R0J106M C2, Output Cap 2.2µF, 25 V, X7R TDK C3225X7R1E225K C3, Input Cap Placeholder (not stuffed) - - C4, Output Cap 4.7µF, 25 V, X7R TDK C3225X7R1E475K C5, VPWR, Input Cap 10µF, 25 V, X5R TDK C3225X5R1E106M D1, Catch Diode 0.4 Vf Schottky, 500mA ON Semiconductor MBR0530T1G D2 15 V Zener Diode Central Semiconductor CMHZ4702 D3 0.4 Vf Schottky, 500mA ON Semiconductor MBR0530T1G L1 3.3µH, 5.4A Coilcraft DO3316P-332 R1 1Ω, 1% Vishay CRCW12061R00FNEA R2 Placeholder (not stuffed) - - R3 100Ω, 1% Vishay CRCW0603100RFKEA R4 Placeholder (not stuffed) - - R5 6.8kΩ, 1% Vishay CRCW08056K80FKEA J1 Jumper Samtec TSW-102-07-T-S SH-J1 Jumper shunt Tyco Electronics 2-382811-1 LEDs 700mA, Vf ≊ 3 .4 V Cree XPEWHT-L1-0000-008E5 SNVA410A – April 2010 – Revised May 2013 Submit Documentation Feedback AN-1996 LM3410X 190mA, LED Driver 6-Pin LLP Evaluation Board Copyright © 2010–2013, Texas Instruments Incorporated 5 PCB Layout 7 www.ti.com PCB Layout Figure 9. Top Layer Figure 10. Bottom Layer 6 AN-1996 LM3410X 190mA, LED Driver 6-Pin LLP Evaluation Board Copyright © 2010–2013, Texas Instruments Incorporated SNVA410A – April 2010 – Revised May 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. 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. 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