LM3405A www.ti.com SNVS508C – OCTOBER 2007 – REVISED MAY 2013 LM3405A 1.6MHz, 1A Constant Current Buck LED Driver with Internal Compensation in Tiny SOT and VSSOP PowerPAD Packages Check for Samples: LM3405A FEATURES DESCRIPTION • • The LM3405A is a 1A constant current buck LED driver designed to provide a simple, high efficiency solution for driving high power LEDs. With a 0.205V reference voltage feedback control to minimize power dissipation, an external resistor sets the current as needed for driving various types of LEDs. Switching frequency is internally set to 1.6MHz, allowing small surface mount inductors and capacitors to be used. The LM3405A utilizes current-mode control and internal compensation offering ease of use and predictable, high performance regulation over a wide range of operating conditions. With a maximum input voltage of 22V, it can drive up to 5 High-Brightness LEDs in series at 1A forward current, with the single LED forward voltage of approximately 3.7V. Additional features include user accessible EN/DIM pin for enabling and PWM dimming of LEDs, thermal shutdown, cycle-by-cycle current limit and overcurrent protection. 1 2 • • • • • • • • • • VIN Operating Range of 3V to 22V Drives up to 5 High-Brightness LEDs in Series at 1A Thin SOT-6 package and VSSOP-8 PowerPAD Packages 1.6MHz Switching Frequency EN/DIM Input for Enabling and PWM Dimming of LEDs 300mΩ NMOS Switch 40nA Shutdown Current at VIN = 5V Internally Compensated Current-mode Control Cycle-by-cycle Current Limit Input Voltage UVLO Over-current Protection Thermal Shutdown APPLICATIONS • • • • • LED Driver Constant Current Source Industrial Lighting LED Flashlights LED Lightbulbs TYPICAL APPLICATION CIRCUIT Efficiency vs LED Current (VIN = 12V) D3 VIN D2 BOOST VIN C3 C1 L1 VOUT SW ON LM3405A D1 C2 OFF IF C4 EN/DIM FB GND R1 1 2 Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet. All trademarks are the property of their respective owners. PRODUCTION DATA information is current as of publication date. Products conform to specifications per the terms of the Texas Instruments standard warranty. Production processing does not necessarily include testing of all parameters. Copyright © 2007–2013, Texas Instruments Incorporated LM3405A SNVS508C – OCTOBER 2007 – REVISED MAY 2013 www.ti.com These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam during storage or handling to prevent electrostatic damage to the MOS gates. CONNECTION DIAGRAMS FB 1 BOOST 1 6 SW GND 2 5 VIN FB 3 4 EN/DIM GND 2 Figure 1. 6-Lead SOT Package See Package Number DDC0006A 8 EN/DIM 7 GND NC 3 6 VIN BOOST 4 5 SW Figure 2. 8-Lead VSSOP PowerPAD Package See Package Number DGN0008A SOT-6 Pin Descriptions Pin No. Name Application Information 1 BOOST Boost voltage that drives the NMOS output switch. A bootstrap capacitor is connected between the BOOST and SW pins. 2 GND Signal and power ground pin. Place the bottom resistor of the feedback network as close as possible to this pin. 3 FB 4 EN/DIM 5 VIN Input supply voltage. Connect a bypass capacitor locally from this pin to GND. 6 SW Switch pin. Connect this pin to the inductor, catch diode, and bootstrap capacitor. Feedback pin. Connect FB to external resistor divider to set output voltage. Enable control input. Logic high enables operation. Toggling this pin with a periodic logic square wave of varying duty cycle at different frequencies controls the brightness of LEDs. Do not allow this pin to float or be greater than VIN + 0.3V. VSSOP-8 PowerPAD Pin Descriptions Pin No. Name 1 FB 2, 7 GND 3 NC 4 BOOST Feedback pin. Connect FB to external resistor divider to set output voltage. Signal and power ground pin. Place the bottom resistor of the feedback network as close as possible to this pin. Tie pins 2, 7 and DAP to one GND plane. No Connection Boost voltage that drives the NMOS output switch. A bootstrap capacitor is connected between the BOOST and SW pins. 5 SW Switch pin. Connect this pin to the inductor, catch diode, and bootstrap capacitor. 6 VIN Input supply voltage. Connect a bypass capacitor locally from this pin to GND. 8 EN/DIM DAP 2 Function Enable control input. Logic high enables operation. Toggling this pin with a periodic logic square wave of varying duty cycle at different frequencies controls the brightness of LEDs. Do not allow this pin to float or be greater than VIN + 0.3V. Attach to power ground pin Submit Documentation Feedback Copyright © 2007–2013, Texas Instruments Incorporated Product Folder Links: LM3405A LM3405A www.ti.com SNVS508C – OCTOBER 2007 – REVISED MAY 2013 ABSOLUTE MAXIMUM RATINGS (1) If Military/Aerospace specified devices are required, contact the Texas Instruments Sales Office/Distributors for availability and specifications. VALUE / UNIT VIN -0.5V to 24V SW Voltage -0.5V to 24V Boost Voltage -0.5V to 30V Boost to SW Voltage -0.5V to 6.0V FB Voltage -0.5V to 3.0V EN/DIM Voltage -0.5V to (VIN + 0.3V) Junction Temperature ESD Susceptibility 150°C (2) 2kV Storage Temperature -65°C to +150°C Soldering Information Infrared/Convection Reflow (15sec) (1) (2) 220°C Absolute Maximum Ratings are limits beyond which damage to the device may occur. Operating Ratings define the conditions under which the device is intended to be functional. For specifications and test conditions, see the Electrical Characteristics. Human body model, 1.5kΩ in series with 100pF. RECOMMENDED OPERATING CONDITIONS (1) VALUE / UNIT VIN 3V to 22V EN/DIM voltage -0.5V to (VIN + 0.3V) Boost to SW Voltage 2.5V to 5.5V Junction Temperature Range -40°C to +125°C Thermal Resistance θJA (2) SOT 118°C/W Thermal Resistance θJA (3) eMSOP8 73°C/W ILED SOT package 400mA ILED VSSOP PowerPAD package (1) (2) (3) 1A Absolute Maximum Ratings are limits beyond which damage to the device may occur. Operating Ratings define the conditions under which the device is intended to be functional. For specifications and test conditions, see the Electrical Characteristics. Thermal shutdown will occur if the junction temperature (TJ) exceeds 165°C. The maximum allowable power dissipation (PD) at any ambient temperature (TA) is PD = (TJ(MAX) – TA)/θJA . This number applies to packages soldered directly onto a 3" x 3" PC board with 2oz. copper on 4 layers in still air. For a 2 layer board using 1 oz. copper in still air, θJA = 204°C/W. Thermal shutdown will occur if the junction temperature (TJ) exceeds 165°C. The maximum allowable power dissipation (PD) at any ambient temperature (TA) is PD = (TJ(MAX) – TA)/θJA . This number applies to packages soldered directly onto a 1" x 0.75" PC board with 1oz. copper on 4 layers in still air. Submit Documentation Feedback Copyright © 2007–2013, Texas Instruments Incorporated Product Folder Links: LM3405A 3 LM3405A SNVS508C – OCTOBER 2007 – REVISED MAY 2013 www.ti.com ELECTRICAL CHARACTERISTICS Unless otherwise specified, VIN = 12V. Limits in standard type are for TJ = 25°C only; limits in boldface type apply over the junction temperature (TJ) range of -40°C to +125°C. Minimum and Maximum limits are specified through test, design, or statistical correlation. Typical values represent the most likely parametric norm, and are provided for reference purposes only. Parameter VFB ΔVFB/(ΔVINxVFB) IFB UVLO Test Conditions Feedback Voltage Feedback Voltage Line Regulation VIN = 3V to 22V Feedback Input Bias Current Sink/Source Under-voltage Lockout VIN Rising Under-voltage Lockout VIN Falling Min Typ Max 0.188 0.205 0.220 0.01 1.9 UVLO Hysteresis fSW Switching Frequency DMAX Maximum Duty Cycle RDS(ON) ICL IQ VEN/DIM_TH IEN/DIM ISW 4 Switch ON Resistance VFB = 0V 85 V %/V 10 250 nA 2.74 2.95 V 2.3 V 0.44 1.2 Units 1.6 V 1.9 94 MHz % SOT (VBOOST - VSW = 3V) 300 600 MSOP (VBOOST - VSW = 3V) 360 700 2.0 2.8 A 1.8 2.8 mA Switch Current Limit VBOOST - VSW = 3V, VIN = 3V Quiescent Current Switching, VFB = 0.195V Quiescent Current (Shutdown) VEN/DIM = 0V Enable Threshold Voltage VEN/DIM Rising Shutdown Threshold Voltage VEN/DIM Falling EN/DIM Pin Current Sink/Source 0.01 µA Switch Leakage VIN = 22V 0.1 µA Submit Documentation Feedback 1.2 mΩ 0.3 µA 1.8 V 0.4 V Copyright © 2007–2013, Texas Instruments Incorporated Product Folder Links: LM3405A LM3405A www.ti.com SNVS508C – OCTOBER 2007 – REVISED MAY 2013 TYPICAL PERFORMANCE CHARACTERISTICS Unless otherwise specified, VIN = 12V, VBOOST - VSW = 5V and TA = 25°C. Efficiency vs LED Current (VIN=5V) Efficiency vs Input Voltage (IF = 1A) Figure 3. Figure 4. Efficiency vs Input Voltage (IF = 0.7A) Efficiency vs Input Voltage (IF = 0.35A) Figure 5. Figure 6. Submit Documentation Feedback Copyright © 2007–2013, Texas Instruments Incorporated Product Folder Links: LM3405A 5 LM3405A SNVS508C – OCTOBER 2007 – REVISED MAY 2013 www.ti.com TYPICAL PERFORMANCE CHARACTERISTICS (continued) Unless otherwise specified, VIN = 12V, VBOOST - VSW = 5V and TA = 25°C. 6 VFB vs Temperature Oscillator Frequency vs Temperature Figure 7. Figure 8. Current Limit vs Temperature SOT RDS(ON) vs Temperature (VBOOST - VSW = 3V) Figure 9. Figure 10. Quiescent Current vs Temperature Startup Response to EN/DIM Signal (VIN = 15V, IF = 0.2A) Figure 11. Figure 12. Submit Documentation Feedback Copyright © 2007–2013, Texas Instruments Incorporated Product Folder Links: LM3405A LM3405A www.ti.com SNVS508C – OCTOBER 2007 – REVISED MAY 2013 BLOCK DIAGRAM Figure 13. Simplified Block Diagram Submit Documentation Feedback Copyright © 2007–2013, Texas Instruments Incorporated Product Folder Links: LM3405A 7 LM3405A SNVS508C – OCTOBER 2007 – REVISED MAY 2013 www.ti.com APPLICATION INFORMATION THEORY OF OPERATION The LM3405A is a PWM, current-mode controled buck switching regulator designed to provide a simple, high efficiency solution for driving LEDs with a preset switching frequency of 1.6MHz. This high frequency allows the LM3405A to operate with small surface mount capacitors and inductors, resulting in LED drivers that need only a minimum amount of board space. The LM3405A is internally compensated, simple to use, and requires few external components. The following description of operation of the LM3405A will refer to the Simplified Block Diagram (Figure 13) and to the waveforms in Figure 14. The LM3405A supplies a regulated output current by switching the internal NMOS power switch at constant frequency and variable duty cycle. A switching cycle begins at the falling edge of the reset pulse generated by the internal oscillator. When this pulse goes low, the output control logic turns on the internal NMOS power switch. During this on-time, the SW pin voltage (VSW) swings up to approximately VIN, and the inductor current (IL) increases with a linear slope. IL is measured by the current sense amplifier, which generates an output proportional to the switch current. The sense signal is summed with the regulator’s corrective ramp and compared to the error amplifier’s output, which is proportional to the difference between the feedback voltage and VREF. When the PWM comparator output goes high, the internal power switch turns off until the next switching cycle begins. During the switch off-time, inductor current discharges through the catch diode D1, which forces the SW pin to swing below ground by the forward voltage (VD1) of the catch diode. The regulator loop adjusts the duty cycle (D) to maintain a constant output current (IF) through the LED, by forcing FB pin voltage to be equal to VREF (0.205V). VSW D = TON/TSW VIN SW Voltage TOFF TON 0 -VD1 IL t TSW ILPK IF 'iL Inductor Current t 0 Figure 14. SW Pin Voltage and Inductor Current Waveforms of LM3405A 8 Submit Documentation Feedback Copyright © 2007–2013, Texas Instruments Incorporated Product Folder Links: LM3405A LM3405A www.ti.com SNVS508C – OCTOBER 2007 – REVISED MAY 2013 BOOST FUNCTION Capacitor C3 and diode D2 in Figure 13 are used to generate a voltage VBOOST. The voltage across C3, VBOOST VSW, is the gate drive voltage to the internal NMOS power switch. To properly drive the internal NMOS switch during its on-time, VBOOST needs to be at least 2.5V greater than VSW. A large value of VBOOST - VSW is recommended to achieve better efficiency by minimizing both the internal switch ON resistance (RDS(ON)), and the switch rise and fall times. However, VBOOST - VSW should not exceed the maximum operating limit of 5.5V. When the LM3405A starts up, internal circuitry from VIN supplies a 20mA current to the BOOST pin, flowing out of the BOOST pin into C3. This current charges C3 to a voltage sufficient to turn the switch on. The BOOST pin will continue to source current to C3 until the voltage at the feedback pin is greater than 123mV. There are various methods to derive VBOOST: 1. From the input voltage (VIN) 2. From the output voltage (VOUT) 3. From a shunt or series zener diode 4. From an external distributed voltage rail (VEXT) The first method is shown in the Simplified Block Diagram of Figure 13. Capacitor C3 is charged via diode D2 by VIN. During a normal switching cycle, when the internal NMOS power switch is off (TOFF) (refer to Figure 14), VBOOST equals VIN minus the forward voltage of D2 (VD2), during which the current in the inductor (L1) forward biases the catch diode D1 (VD1). Therefore the gate drive voltage stored across C3 is: VBOOST - VSW = VIN - VD2 + VD1 (1) When the NMOS switch turns on (TON), the switch pin rises to: VSW = VIN – (RDS(ON) x IL) (2) Since the voltage across C3 remains unchanged, VBOOST is forced to rise thus reverse biasing D2. The voltage at VBOOST is then: VBOOST = 2VIN – (RDS(ON) x IL) – VD2 + VD1 (3) Depending on the quality of the diodes D1 and D2, the gate drive voltage in this method can be slightly less or larger than the input voltage VIN. For best performance, ensure that the variation of the input supply does not cause the gate drive voltage to fall outside the recommended range: 2.5V < VIN - VD2 + VD1 < 5.5V (4) The second method for deriving the boost voltage is to connect D2 to the output as shown in Figure 15. The gate drive voltage in this configuration is: VBOOST - VSW = VOUT – VD2 + VD1 (5) Since the gate drive voltage needs to be in the range of 2.5V to 5.5V, the output voltage VOUT should be limited to a certain range. For the calculation of VOUT, see OUTPUT VOLTAGE section. Figure 15. VBOOST Derived from VOUT Submit Documentation Feedback Copyright © 2007–2013, Texas Instruments Incorporated Product Folder Links: LM3405A 9 LM3405A SNVS508C – OCTOBER 2007 – REVISED MAY 2013 www.ti.com The third method can be used in the applications where both VIN and VOUT are greater than 5.5V. In these cases, C3 cannot be charged directly from these voltages; instead C3 can be charged from VIN or VOUT minus a zener voltage (VD3) by placing a zener diode D3 in series with D2 as shown in Figure 16. When using a series zener diode from the input, the gate drive voltage is VIN - VD3 - VD2 + VD1. Figure 16. VBOOST Derived from VIN through a Series Zener An alternate method is to place the zener diode D3 in a shunt configuration as shown in Figure 17. A small 350mW to 500mW, 5.1V zener in a SOT or SOD package can be used for this purpose. A small ceramic capacitor such as a 6.3V, 0.1µF capacitor (C5) should be placed in parallel with the zener diode. When the internal NMOS switch turns on, a pulse of current is drawn to charge the internal NMOS gate capacitance. The 0.1µF parallel shunt capacitor ensures that the VBOOST voltage is maintained during this time. Resistor R2 should be chosen to provide enough RMS current to the zener diode and to the BOOST pin. A recommended choice for the zener current (IZENER) is 1mA. The current IBOOST into the BOOST pin supplies the gate current of the NMOS power switch. It reaches a maximum of around 3.6mA at the highest gate drive voltage of 5.5V over the LM3405A operating range. For the worst case IBOOST, increase the current by 50%. In that case, the maximum boost current will be: IBOOST-MAX = 1.5 x 3.6mA = 5.4mA (6) R2 will then be given by: R2 = (VIN - VZENER) / (IBOOST_MAX + IZENER) (7) For example, let VIN = 12V, VZENER = 5V, IZENER = 1mA, then: R2 = (12V - 5V) / (5.4mA + 1mA) = 1.09kΩ (8) Figure 17. VBOOST derived from VIN through a Shunt Zener The fourth method can be used in an application which has an external low voltage rail, VEXT. C3 can be charged through D2 from VEXT, independent of VIN and VOUT voltage levels. Again for best performance, ensure that the gate drive voltage, VEXT - VD2 + VD1, falls in the range of 2.5V to 5.5V. 10 Submit Documentation Feedback Copyright © 2007–2013, Texas Instruments Incorporated Product Folder Links: LM3405A LM3405A www.ti.com SNVS508C – OCTOBER 2007 – REVISED MAY 2013 SETTING THE LED CURRENT LM3405A is a constant current buck regulator. The LEDs are connected between VOUT and the FB pin as shown in the Typical Application Circuit. The FB pin is at 0.205V in regulation and therefore the LED current IF is set by VFB and resistor R1 from FB to ground by the following equation: IF = VFB / R1 (9) IF should not exceed the 1A current capability of LM3405A and therefore R1 minimum must be approximately 0.2Ω. IF should also be kept above 200mA for stable operation, and therefore R1 maximum must be approximately 1Ω. If average LED currents less than 200mA are desired, the EN/DIM pin can be used for PWM dimming. See LED PWM DIMMING section. OUTPUT VOLTAGE The output voltage is primarily determined by the number of LEDs (n) connected from VOUT to FB pin and therefore VOUT can be written as : VOUT = ((n x VF) + VFB) (10) where VF is the forward voltage of one LED at the set LED current level (see LED manufacturer datasheet for forward characteristics curve). ENABLE MODE / SHUTDOWN MODE The LM3405A has both enable and shutdown modes that are controlled by the EN/DIM pin. Connecting a voltage source greater than 1.8V to the EN/DIM pin enables the operation of LM3405A, while reducing this voltage below 0.4V places the part in a low quiescent current (0.3µA typical) shutdown mode. There is no internal pull-up on EN/DIM pin, therefore an external signal is required to initiate switching. Do not allow this pin to float or rise to 0.3V above VIN. It should be noted that when the EN/DIM pin voltage rises above 1.8V while the input voltage is greater than UVLO, there is a finite delay before switching starts. During this delay the LM3405A will go through a power on reset state after which the internal soft-start process commences. The soft-start process limits the inrush current and brings up the LED current (IF) in a smooth and controlled fashion. The total combined duration of the power on reset delay, soft-start delay and the delay to fully establish the LED current is in the order of 100µs (refer to Figure 22). The simplest way to enable the operation of LM3405A is to connect the EN/DIM pin to VIN which allows self startup of LM3405A whenever the input voltage is applied. However, when an input voltage of slow rise time is used to power the application and if both the input voltage and the output voltage are not fully established before the soft-start time elapses, the control circuit will command maximum duty cycle operation of the internal power switch to bring up the output voltage rapidly. When the feedback pin voltage exceeds 0.205V, the duty cycle will have to reduce from the maximum value accordingly, to maintain regulation. It takes a finite amount of time for this reduction of duty cycle and this will result in a spike in LED current for a short duration as shown in Figure 18. In applications where this LED current overshoot is undesirable, EN/DIM pin voltage can be separately applied and delayed such that VIN is fully established before the EN/DIM pin voltage reaches the enable threshold. The effect of delaying EN/DIM with respect to VIN on the LED current is shown in Figure 19. For a fast rising input voltage (200µs for example), there is no need to delay the EN/DIM signal since soft-start can smoothly bring up the LED current as shown in Figure 20. Submit Documentation Feedback Copyright © 2007–2013, Texas Instruments Incorporated Product Folder Links: LM3405A 11 LM3405A SNVS508C – OCTOBER 2007 – REVISED MAY 2013 www.ti.com Figure 18. Startup Response to VIN with 5ms Rise Time Figure 19. Startup Response to VIN with EN/DIM Delayed Figure 20. Startup Response to VIN with 200µs Rise Time LED PWM DIMMING The LED brightness can be controlled by applying a periodic pulse signal to the EN/DIM pin and varying its frequency and/or duty cycle. This so-called PWM dimming method controls the average light output by pulsing the LED current between the set value and zero. A logic high level at the EN/DIM pin turns on the LED current whereas a logic low level turns off the LED current. Figure 21 shows a typical LED current waveform in PWM dimming mode. As explained in the previous section, there is approximately a 100µs delay from the EN/DIM signal going high to fully establishing the LED current as shown in Figure 22. This 100µs delay sets a maximum frequency limit for the driving signal that can be applied to the EN/DIM pin for PWM dimming. Figure 23 shows the average LED current versus duty cycle of PWM dimming signal for various frequencies. The applicable frequency range to drive LM3405A for PWM dimming is from 100Hz to 5kHz. The dimming ratio reduces drastically when the applied PWM dimming frequency is greater than 5kHz. 12 Submit Documentation Feedback Copyright © 2007–2013, Texas Instruments Incorporated Product Folder Links: LM3405A LM3405A www.ti.com SNVS508C – OCTOBER 2007 – REVISED MAY 2013 Figure 21. PWM Dimming of LEDs Using the EN/DIM Pin Figure 22. Startup Response to EN/DIM with IF = 1A Figure 23. Average LED Current vs Duty Cycle of PWM Dimming Signal at EN/DIM Pin UNDER-VOLTAGE LOCKOUT Under-voltage lockout (UVLO) prevents the LM3405A from operating until the input voltage exceeds 2.74V (typical). The UVLO threshold has approximately 440mV of hysteresis, so the part will operate until VIN drops below 2.3V (typical). Hysteresis prevents the part from turning off during power up if VIN is non-monotonic. CURRENT LIMIT The LM3405A uses cycle-by-cycle current limit to protect the internal power switch. During each switching cycle, a current limit comparator detects if the power switch current exceeds 2.0A (typical), and turns off the switch until the next switching cycle begins. OVER-CURRENT PROTECTION The LM3405A has a built in over-current comparator that compares the FB pin voltage to a threshold voltage that is 60% higher than the internal reference VREF. Once the FB pin voltage exceeds this threshold level (typically 328mV), the internal NMOS power switch is turned off, which allows the feedback voltage to decrease towards regulation. This threshold provides an upper limit for the LED current. LED current overshoot is limited to 328mV/R1 by this comparator during transients. Submit Documentation Feedback Copyright © 2007–2013, Texas Instruments Incorporated Product Folder Links: LM3405A 13 LM3405A SNVS508C – OCTOBER 2007 – REVISED MAY 2013 www.ti.com THERMAL SHUTDOWN Thermal shutdown limits total power dissipation by turning off the internal power switch when the IC junction temperature exceeds 165°C. After thermal shutdown occurs, the power switch does not turn on until the junction temperature drops below approximately 150°C. DESIGN GUIDE INDUCTOR (L1) The Duty Cycle (D) can be approximated quickly using the ratio of output voltage (VOUT) to input voltage (VIN): D= VOUT VIN (11) The catch diode (D1) forward voltage drop and the voltage drop across the internal NMOS must be included to calculate a more accurate duty cycle. Calculate D by using the following formula: VOUT + VD1 D= VIN + VD1 - VSW (12) VSW can be approximated by: VSW = IF x RDS(ON) (13) The diode forward drop (VD1) can range from 0.3V to 0.7V depending on the quality of the diode. The lower VD1 is, the higher the operating efficiency of the converter. The inductor value determines the output ripple current (ΔiL, as defined in Figure 14). Lower inductor values decrease the size of the inductor, but increases the output ripple current. An increase in the inductor value will decrease the output ripple current. The ratio of ripple current to LED current is optimized when it is set between 0.3 and 0.4 at 1A LED current. This ratio r is defined as: r= 'iL lF (14) One must also ensure that the minimum current limit (1.2A) is not exceeded, so the peak current in the inductor must be calculated. The peak current (ILPK) in the inductor is calculated as: ILPK = IF + ΔiL/2 (15) When the designed maximum output current is reduced, the ratio r can be increased. At a current of 0.2A, r can be made as high as 0.7. The ripple ratio can be increased at lighter loads because the net ripple is actually quite low, and if r remains constant the inductor value can be made quite large. An equation empirically developed for the maximum ripple ratio at any current below 2A is: r = 0.387 x IOUT-0.3667 (16) Note that this is just a guideline. The LM3405A operates at a high frequency allowing the use of ceramic output capacitors without compromising transient response. Ceramic capacitors allow higher inductor ripple without significantly increasing LED current ripple. See the output capacitor and feed-forward capacitor sections for more details on LED current ripple. Now that the ripple current or ripple ratio is determined, the inductance is calculated by: L= VOUT + VD1 IF x r x fSW x (1-D) (17) where fSW is the switching frequency and IF is the LED current. When selecting an inductor, make sure that it is capable of supporting the peak output current without saturating. Inductor saturation will result in a sudden reduction in inductance and prevent the regulator from operating correctly. Because of the operating frequency of the LM3405A, ferrite based inductors are preferred to minimize core losses. This presents little restriction since the variety of ferrite based inductors is huge. Lastly, inductors with lower series resistance (DCR) will provide better operating efficiency. For recommended inductor selection, refer to Circuit Examples and Recommended Inductance Range in Table 1. 14 Submit Documentation Feedback Copyright © 2007–2013, Texas Instruments Incorporated Product Folder Links: LM3405A LM3405A www.ti.com SNVS508C – OCTOBER 2007 – REVISED MAY 2013 Table 1. Recommended Inductance Range IF Inductance Range and Inductor Current Ripple 6.8µH-15µH 1.0A Inductance 6.8µH 10µH 15µH ΔiL / IF (1) 51% 36% 24% 10µH 15µH 22µH 58% 39% 26% 15µH 22µH 27µH 116% 79% 65% 10µH-22µH 0.6A Inductance ΔiL / IF (1) 15µH-27µH 0.2A Inductance ΔiL / IF (1) (1) Maximum over full range of VIN and VOUT. INPUT CAPACITOR (C1) An input capacitor is necessary to ensure that VIN does not drop excessively during switching transients. The primary specifications of the input capacitor are capacitance, voltage rating, RMS current rating, and ESL (Equivalent Series Inductance). The input voltage rating is specifically stated by the capacitor manufacturer. Make sure to check any recommended deratings and also verify if there is any significant change in capacitance at the operating input voltage and the operating temperature. The input capacitor maximum RMS input current rating (IRMS-IN) must be greater than: IRMS-IN = IF x r2 Dx 1-D+ 12 (18) It can be shown from the above equation that maximum RMS capacitor current occurs when D = 0.5. Always calculate the RMS at the point where the duty cycle D, is closest to 0.5. The ESL of an input capacitor is usually determined by the effective cross sectional area of the current path. A large leaded capacitor will have high ESL and an 0805 ceramic chip capacitor will have very low ESL. At the operating frequency of the LM3405A, certain capacitors may have an ESL so large that the resulting inductive impedance (2πfL) will be higher than that required to provide stable operation. It is strongly recommended to use ceramic capacitors due to their low ESR and low ESL. A 10µF multilayer ceramic capacitor (MLCC) is a good choice for most applications. In cases where large capacitance is required, use surface mount capacitors such as Tantalum capacitors and place at least a 1µF ceramic capacitor close to the VIN pin. For MLCCs it is recommended to use X7R or X5R dielectrics. Consult capacitor manufacturer datasheet to see how rated capacitance varies over operating conditions. OUTPUT CAPACITOR (C2) The output capacitor is selected based upon the desired reduction in LED current ripple. A 1µF ceramic capacitor results in very low LED current ripple for most applications. Due to the high switching frequency, the 1µF capacitor alone (without feed-forward capacitor C4) can filter more than 90% of the inductor current ripple for most applications where the sum of LED dynamic resistance and R1 is larger than 1Ω. Since the internal compensation is tailored for small output capacitance with very low ESR, it is strongly recommended to use a ceramic capacitor with capacitance less than 3.3µF. Given the availability and quality of MLCCs and the expected output voltage of designs using the LM3405A, there is really no need to review other capacitor technologies. A benefit of ceramic capacitors is their ability to bypass high frequency noise. A certain amount of switching edge noise will couple through the parasitic capacitances in the inductor to the output. A ceramic capacitor will bypass this noise. In cases where large capacitance is required, use Electrolytic or Tantalum capacitors with large ESR, and verify the loop performance on the bench. Like the input capacitor, multilayer ceramic capacitors are recommended X7R or X5R. Again, verify actual capacitance at the desired operating voltage and temperature. Check the RMS current rating of the capacitor. The maximum RMS current rating of the capacitor is: IRMS-OUT = IF x r 12 (19) One may select a 1206 size ceramic capacitor for C2 since its current rating is typically higher than 1A, more than enough for the requirement. Submit Documentation Feedback Copyright © 2007–2013, Texas Instruments Incorporated Product Folder Links: LM3405A 15 LM3405A SNVS508C – OCTOBER 2007 – REVISED MAY 2013 www.ti.com FEED-FORWARD CAPACITOR (C4) The feed-forward capacitor (designated as C4) connected in parallel with the LED string is required to provide multiple benefits to the LED driver design. It greatly improves the large signal transient response and suppresses LED current overshoot that may otherwise occur during PWM dimming; it also helps to shape the rise and fall times of the LED current pulse during PWM dimming thus reducing EMI emission; it reduces LED current ripple by bypassing some of inductor ripple from flowing through the LED. For most applications, a 1µF ceramic capacitor is sufficient. In fact, the combination of a 1µF feed-forward ceramic capacitor and a 1µF output ceramic capacitor leads to less than 1% current ripple flowing through the LED. Lower and higher C4 values can be used, but bench validation is required to ensure the performance meets the application requirement. Figure 24 shows a typical LED current waveform during PWM dimming without feed-forward capacitor. At the beginning of each PWM cycle, overshoot can be seen in the LED current. Adding a 1µF feed-forward capacitor can totally remove the overshoot as shown in Figure 25. Figure 24. PWM Dimming without Feed-Forward Capacitor Figure 25. PWM Dimming with a 1µF Feed-Forward Capacitor CATCH DIODE (D1) The catch diode (D1) conducts during the switch off-time. A Schottky diode is required for its fast switching time and low forward voltage drop. The catch diode should be chosen such that its current rating is greater than: ID1 = IF x (1-D) (20) The reverse breakdown rating of the diode must be at least the maximum input voltage plus appropriate margin. To improve efficiency, choose a Schottky diode with a low forward voltage drop. BOOST DIODE (D2) A standard diode such as the 1N4148 type is recommended. For VBOOST circuits derived from voltages less than 3.3V, a small-signal Schottky diode is recommended for better efficiency. A good choice is the BAT54 small signal diode. BOOST CAPACITOR (C3) A 0.01µF ceramic capacitor with a voltage rating of at least 6.3V is sufficient. The X7R and X5R MLCCs provide the best performance. POWER LOSS ESTIMATION The main power loss in LM3405A includes three basic types of loss in the internal power switch: conduction loss, switching loss, and gate charge loss. In addition, there is loss associated with the power required for the internal circuitry of IC. The conduction loss is calculated as: (21) 16 Submit Documentation Feedback Copyright © 2007–2013, Texas Instruments Incorporated Product Folder Links: LM3405A LM3405A www.ti.com SNVS508C – OCTOBER 2007 – REVISED MAY 2013 If the inductor ripple current is fairly small (for example, less than 40%) , the conduction loss can be simplified to: PCOND = IF2 x RDS(ON) x D (22) The switching loss occurs during the switch on and off transition periods, where voltage and current overlap resulting in power loss. The simplest means to determine this loss is to empirically measure the rise and fall times (10% to 90%) of the voltage at the switch pin. Switching power loss is calculated as follows: PSW = 0.5 x VIN x IF x fSW x ( TRISE + TFALL ) (23) The gate charge loss is associated with the gate charge QG required to drive the switch: PG = fSW x VIN x QG (24) The power loss required for operation of the internal circuitry: PQ = IQ x VIN (25) IQ is the quiescent operating current, and is typically around 1.8mA for the LM3405A. The total power loss in the IC is: PINTERNAL = PCOND + PSW + PG + PQ (26) An example of power losses for a typical application is shown in Table 2: Table 2. Power Loss Tabulation Conditions Power loss VIN 12V VOUT 3.9V IOUT 1.0A VD1 0.45V RDS(ON) 300mΩ fSW 1.6MHz PCOND 108mW TRISE 18ns TFALL 12ns PSW 288mW IQ QG 1.8mA PQ 22mW 1.4nC PG 27mW D is calculated to be 0.36 Σ ( PCOND + PSW + PQ + PG ) = PINTERNAL PINTERNAL = 445mW (27) (28) PCB Layout Considerations When planning the layout there are a few things to consider when trying to achieve a clean, regulated output. The most important consideration when completing the layout is the close coupling of the GND connections of the input capacitor C1 and the catch diode D1. These ground ends should be close to one another and be connected to the GND plane with at least two through-holes. Place these components as close to the IC as possible. The next consideration is the location of the GND connection of the output capacitor C2, which should be near the GND connections of C1 and D1. There should be a continuous ground plane on the bottom layer of a two-layer board except under the switching node island. The FB pin is a high impedance node and care should be taken to make the FB trace short to avoid noise pickup that causes inaccurate regulation. The LED current setting resistor R1 should be placed as close as possible to the IC, with the GND of R1 placed as close as possible to the GND of the IC. The VOUT trace to LED anode should be routed away from the inductor and any other traces that are switching. High AC currents flow through the VIN, SW and VOUT traces, so they should be as short and wide as possible. Radiated noise can be decreased by choosing a shielded inductor. The remaining components should also be placed as close as possible to the IC. See Application Report AN1229 (SNVA054) for further considerations and the LM3405A demo board as an example of a four-layer layout. Submit Documentation Feedback Copyright © 2007–2013, Texas Instruments Incorporated Product Folder Links: LM3405A 17 LM3405A SNVS508C – OCTOBER 2007 – REVISED MAY 2013 www.ti.com LM3405A Circuit Examples D2 VIN BOOST VIN C3 C1 L1 VOUT SW LM3405A C2 D1 DC or PWM C4 EN/DIM IF LED1 FB GND R1 Figure 26. VBOOST derived from VIN (VIN = 5V, IF = 1A) Table 3. Bill of Materials for Figure 26 Part ID Part Value Part Number Manufacturer U1 1A LED Driver LM3405A Texas Instruments Semiconductor C1, Input Cap 10µF, 6.3V, X5R C3216X5R0J106M TDK C2, Output Cap 1µF, 10V, X7R GRM319R71A105KC01D Murata C3, Boost Cap 0.01µF, 16V, X7R 0805YC103KAT2A AVX C4, Feedforward Cap 1µF, 10V, X7R GRM319R71A105KC01D Murata D1, Catch Diode Schottky, 0.37V at 1A, VR = 10V MBRM110LT1G ON Semiconductor D2, Boost Diode Schottky, 0.36V at 15mA CMDSH-3 Central Semiconductor L1 4.7µH, 1.6A SLF6028T-4R7M1R6 TDK R1 0.2Ω, 0.5W, 1% WSL2010R2000FEA Vishay LED1 1.5A, White LED LXK2-PW14 Lumileds 18 Submit Documentation Feedback Copyright © 2007–2013, Texas Instruments Incorporated Product Folder Links: LM3405A LM3405A www.ti.com SNVS508C – OCTOBER 2007 – REVISED MAY 2013 D2 VIN BOOST VIN C3 C1 L1 VOUT SW LM3405A C2 D1 DC or PWM C4 EN/DIM IF LED1 FB GND R1 Figure 27. VBOOST derived from VOUT (VIN = 12V, IF = 1A) Table 4. Bill of Materials for Figure 27 Part ID Part Value Part Number Manufacturer U1 1A LED Driver LM3405A Texas Instruments C1, Input Cap 10µF, 25V, X5R ECJ-3YB1E106K Panasonic C2, Output Cap 1µF, 10V, X7R GRM319R71A105KC01D Murata C3, Boost Cap 0.01µF, 16V, X7R 0805YC103KAT2A AVX C4, Feedforward Cap 1µF, 10V, X7R GRM319R71A105KC01D Murata D1, Catch Diode Schottky, 0.5V at 1A, VR = 30V SS13 Vishay D2, Boost Diode Schottky, 0.36V at 15mA CMDSH-3 Central Semiconductor L1 4.7µH, 1.6A SLF6028T-4R7M1R6 TDK R1 0.2Ω, 0.5W, 1% WSL2010R2000FEA Vishay LED1 1.5A, White LED LXK2-PW14 Lumileds Submit Documentation Feedback Copyright © 2007–2013, Texas Instruments Incorporated Product Folder Links: LM3405A 19 LM3405A SNVS508C – OCTOBER 2007 – REVISED MAY 2013 www.ti.com C5 D3 R2 D2 VIN BOOST VIN C3 C1 L1 VOUT SW LM3405A D1 C2 C4 DC or PWM IF LED1 EN/DIM FB GND R1 Figure 28. VBOOST derived from VIN through a Shunt Zener Diode (D3) (VIN = 18V, IF = 1A) Table 5. Bill of Materials for Figure 28 Part ID Part Value Part Number Manufacturer U1 1A LED Driver LM3405A Texas Instruments Semiconductor C1, Input Cap 10µF, 25V, X5R ECJ-3YB1E106K Panasonic C2, Output Cap 1µF, 10V, X7R GRM319R71A105KC01D Murata C3, Boost Cap 0.01µF, 16V, X7R 0805YC103KAT2A AVX C4, Feedforward Cap 1µF, 10V, X7R GRM319R71A105KC01D Murata C5, Shunt Cap 0.1µF, 16V, X7R GRM219R71C104KA01D Murata D1, Catch Diode Schottky, 0.5V at 1A, VR = 30V SS13 Vishay D2, Boost Diode Schottky, 0.36V at 15mA CMDSH-3 Central Semiconductor D3, Zener Diode 4.7V, 350mW, SOT-23 BZX84C4V7 Fairchild L1 6.8µH, 1.5A SLF6028T-6R8M1R5 TDK R1 0.2Ω, 0.5W, 1% WSL2010R2000FEA Vishay R2 1.91kΩ, 1% CRCW08051K91FKEA Vishay LED1 1.5A, White LED LXK2-PW14 Lumileds 20 Submit Documentation Feedback Copyright © 2007–2013, Texas Instruments Incorporated Product Folder Links: LM3405A LM3405A www.ti.com SNVS508C – OCTOBER 2007 – REVISED MAY 2013 D3 D2 BOOST VIN VIN C3 C1 L1 VOUT SW LM3405A DC or PWM D1 C2 C4 EN/DIM IF LED1 FB GND R1 Figure 29. VBOOST derived from VIN through a Series Zener Diode (D3) (VIN = 15V, IF = 1A) Table 6. Bill of Materials for Figure 29 Part ID Part Value Part Number Manufacturer U1 1A LED Driver LM3405A Texas Instruments C1, Input Cap 10µF, 25V, X5R ECJ-3YB1E106K Panasonic C2, Output Cap 1µF, 10V, X7R GRM319R71A105KC01D Murata C3, Boost Cap 0.01µF, 16V, X7R 0805YC103KAT2A AVX C4, Feedforward Cap 1µF, 10V, X7R GRM319R71A105KC01D Murata D1, Catch Diode Schottky, 0.5V at 1A, VR = 30V SS13 Vishay D2, Boost Diode Schottky, 0.36V at 15mA CMDSH-3 Central Semiconductor D3, Zener Diode 11V, 350mW, SOT-23 BZX84C11 Fairchild L1 6.8µH, 1.5A SLF6028T-6R8M1R5 TDK R1 0.2Ω, 0.5W, 1% WSL2010R2000FEA Vishay LED1 1.5A, White LED LXK2-PW14 Lumileds Submit Documentation Feedback Copyright © 2007–2013, Texas Instruments Incorporated Product Folder Links: LM3405A 21 LM3405A SNVS508C – OCTOBER 2007 – REVISED MAY 2013 www.ti.com D3 D2 VIN BOOST VIN C3 C1 L1 VOUT SW LM3405A C2 D1 LED1 IF C4 DC or PWM EN/DIM LED2 FB GND R1 Figure 30. VBOOST derived from VOUT through a Series Zener Diode (D3) ( VIN = 18V, IF = 1A ) Table 7. Bill of Materials for Figure 30 Part ID Part Value Part Number Manufacturer U1 1A LED Driver LM3405A Texas Instruments C1, Input Cap 10µF, 25V, X5R ECJ-3YB1E106K Panasonic C2, Output Cap 1µF, 16V, X7R GRM319R71A105KC01D Murata C3, Boost Cap 0.01µF, 16V, X7R 0805YC103KAT2A AVX C4, Feedforward Cap 1µF, 16V, X7R GRM319R71A105KC01D Murata D1, Catch Diode Schottky, 0.5V at 1A, VR = 30V SS13 Vishay D2, Boost Diode Schottky, 0.36V at 15mA CMDSH-3 Central Semiconductor D3, Zener Diode 3.6V, 350mW, SOT-23 BZX84C3V6 Fairchild L1 6.8µH, 1.5A SLF6028T-6R8M1R5 TDK R1 0.2Ω, 0.5W, 1% WSL2010R2000FEA Vishay LED1 1.5A, White LED LXK2-PW14 Lumileds LED2 1.5A, White LED LXK2-PW14 Lumileds 22 Submit Documentation Feedback Copyright © 2007–2013, Texas Instruments Incorporated Product Folder Links: LM3405A LM3405A www.ti.com SNVS508C – OCTOBER 2007 – REVISED MAY 2013 Figure 31. LED MR16 Lamp Application ( VIN = 12V AC, IF = 0.75A ) Table 8. Bill of Materials for Figure 31 Part ID Part Value Part Number Manufacturer U1 1A LED Driver LM3405A Texas Instruments C1, Input Cap 10µF, 25V, X5R ECJ-3YB1E106K Panasonic C2, Output Cap 1µF, 10V, X7R GRM319R71A105KC01D Murata C3, Boost Cap 0.01µF, 16V, X7R 0805YC103KAT2A AVX C5, Input Cap 220µF, 25V, electrolytic ECE-A1EN221U Panasonic D1, Catch Diode Schottky, 0.5V at 1A, VR = 30V SS13 Vishay D2, Boost Diode Schottky, 0.36V at 15mA CMDSH-3 Central Semiconductor D3, Rectifier Diode Schottky, 0.385V at 500mA CMHSH5-2L Central Semiconductor D4, Rectifier Diode Schottky, 0.385V at 500mA CMHSH5-2L Central Semiconductor D5, Rectifier Diode Schottky, 0.385V at 500mA CMHSH5-2L Central Semiconductor D6, Rectifier Diode Schottky, 0.385V at 500mA CMHSH5-2L Central Semiconductor L1 6.8µH, 1.5A SLF6028T-6R8M1R5 TDK R1 0.27Ω, 0.33W, 1% ERJ8BQFR27 Panasonic LED1 1A, White LED LXHL-PW09 Lumileds Submit Documentation Feedback Copyright © 2007–2013, Texas Instruments Incorporated Product Folder Links: LM3405A 23 LM3405A SNVS508C – OCTOBER 2007 – REVISED MAY 2013 www.ti.com REVISION HISTORY Changes from Revision B (May 2013) to Revision C • 24 Page Changed layout of National Data Sheet to TI format .......................................................................................................... 23 Submit Documentation Feedback Copyright © 2007–2013, Texas Instruments Incorporated Product Folder Links: LM3405A PACKAGE OPTION ADDENDUM www.ti.com 2-May-2013 PACKAGING INFORMATION Orderable Device Status (1) Package Type Package Pins Package Drawing Qty Eco Plan Lead/Ball Finish (2) MSL Peak Temp Op Temp (°C) Top-Side Markings (3) (4) LM3405AXMK/NOPB ACTIVE SOT DDC 6 1000 Green (RoHS & no Sb/Br) CU SN Level-1-260C-UNLIM -40 to 125 SSEB LM3405AXMKE/NOPB ACTIVE SOT DDC 6 250 Green (RoHS & no Sb/Br) CU SN Level-1-260C-UNLIM -40 to 125 SSEB LM3405AXMKX/NOPB ACTIVE SOT DDC 6 3000 Green (RoHS & no Sb/Br) CU SN Level-1-260C-UNLIM -40 to 125 SSEB LM3405AXMY/NOPB ACTIVE MSOPPowerPAD DGN 8 1000 Green (RoHS & no Sb/Br) CU SN Level-1-260C-UNLIM SVSA LM3405AXMYX/NOPB ACTIVE MSOPPowerPAD DGN 8 3500 Green (RoHS & no Sb/Br) CU SN Level-1-260C-UNLIM SVSA (1) The marketing status values are defined as follows: ACTIVE: Product device recommended for new designs. LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect. NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design. PREVIEW: Device has been announced but is not in production. Samples may or may not be available. OBSOLETE: TI has discontinued the production of the device. (2) Eco Plan - The planned eco-friendly classification: Pb-Free (RoHS), Pb-Free (RoHS Exempt), or Green (RoHS & no Sb/Br) - please check http://www.ti.com/productcontent for the latest availability information and additional product content details. TBD: The Pb-Free/Green conversion plan has not been defined. Pb-Free (RoHS): TI's terms "Lead-Free" or "Pb-Free" mean semiconductor products that are compatible with the current RoHS requirements for all 6 substances, including the requirement that lead not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, TI Pb-Free products are suitable for use in specified lead-free processes. Pb-Free (RoHS Exempt): This component has a RoHS exemption for either 1) lead-based flip-chip solder bumps used between the die and package, or 2) lead-based die adhesive used between the die and leadframe. The component is otherwise considered Pb-Free (RoHS compatible) as defined above. Green (RoHS & no Sb/Br): TI defines "Green" to mean Pb-Free (RoHS compatible), and free of Bromine (Br) and Antimony (Sb) based flame retardants (Br or Sb do not exceed 0.1% by weight in homogeneous material) (3) MSL, Peak Temp. -- The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature. (4) Multiple Top-Side Markings will be inside parentheses. Only one Top-Side Marking contained in parentheses and separated by a "~" will appear on a device. If a line is indented then it is a continuation of the previous line and the two combined represent the entire Top-Side Marking for that device. Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided. TI bases its knowledge and belief on information provided by third parties, and makes no representation or warranty as to the accuracy of such information. Efforts are underway to better integrate information from third parties. TI has taken and continues to take reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on incoming materials and chemicals. TI and TI suppliers consider certain information to be proprietary, and thus CAS numbers and other limited information may not be available for release. Addendum-Page 1 Samples PACKAGE OPTION ADDENDUM www.ti.com 2-May-2013 In no event shall TI's liability arising out of such information exceed the total purchase price of the TI part(s) at issue in this document sold by TI to Customer on an annual basis. Addendum-Page 2 PACKAGE MATERIALS INFORMATION www.ti.com 11-Oct-2013 TAPE AND REEL INFORMATION *All dimensions are nominal Device Package Package Pins Type Drawing LM3405AXMK/NOPB SOT DDC 6 LM3405AXMKE/NOPB SOT DDC LM3405AXMKX/NOPB SOT DDC LM3405AXMY/NOPB MSOPPower PAD LM3405AXMYX/NOPB MSOPPower PAD SPQ Reel Reel A0 Diameter Width (mm) (mm) W1 (mm) B0 (mm) K0 (mm) P1 (mm) W Pin1 (mm) Quadrant 1000 178.0 8.4 3.2 3.2 1.4 4.0 8.0 Q3 6 250 178.0 8.4 3.2 3.2 1.4 4.0 8.0 Q3 6 3000 178.0 8.4 3.2 3.2 1.4 4.0 8.0 Q3 DGN 8 1000 178.0 12.4 5.3 3.4 1.4 8.0 12.0 Q1 DGN 8 3500 330.0 12.4 5.3 3.4 1.4 8.0 12.0 Q1 Pack Materials-Page 1 PACKAGE MATERIALS INFORMATION www.ti.com 11-Oct-2013 *All dimensions are nominal Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm) LM3405AXMK/NOPB SOT DDC 6 1000 210.0 185.0 35.0 LM3405AXMKE/NOPB SOT DDC 6 250 210.0 185.0 35.0 LM3405AXMKX/NOPB SOT DDC 6 3000 210.0 185.0 35.0 LM3405AXMY/NOPB MSOP-PowerPAD DGN 8 1000 210.0 185.0 35.0 LM3405AXMYX/NOPB MSOP-PowerPAD DGN 8 3500 367.0 367.0 35.0 Pack Materials-Page 2 MECHANICAL DATA DGN0008A MUY08A (Rev A) BOTTOM VIEW www.ti.com 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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