National Semiconductor LM3410 Technical data

April 8, 2008

LM3410 PowerWise® 525kHz/1.6MHz, Constant Current Boost and SEPIC LED Driver with Internal Compensation

LM3410 PowerWise

Internal Compensation

General Description

The LM3410 constant current LED driver is a monolithic, high frequency, PWM DC/DC converter in 5-pin SOT23, 6-pin LLP, & 8-pin eMSOP packages. With a minimum of external components the LM3410 is easy to use. It can drive 2.8A typical peak currents with an internal 170 mΩ NMOS switch. Switching frequency is internally set to either 525 kHz or 1.60 MHz, allowing the use of extremely small surface mount inductors and chip capacitors. Even though the operating frequency is high, efficiencies up to 88% are easy to achieve. External shutdown is included, featuring an ultra-low standby current of 80 nA. The LM3410 utilizes current-mode control and internal compensation to provide high-performance over a wide range of operating conditions. Additional features include dimming, cycle-by-cycle current limit, and thermal shutdown.

Typical Boost Application Circuit

Features

Space Saving SOT23-5 & 6-LLP Package

■

Input voltage range of 2.7V to 5.5V

■

Output voltage range of 3V to 24V

■

2.8A Typical Switch Current

■

High Switching Frequency

■

525 KHz (LM3410-Y)

—

1.6 MHz (LM3410-X)

— 170 mΩ NMOS Switch

■

190 mV Internal Voltage Reference

■

Internal Soft-Start

■

Current-Mode, PWM Operation

■

Thermal Shutdown

■

Applications

LED Backlight Current Source

■

LiIon Backlight OLED & HB LED Driver

■

Handheld Devices

■

LED Flash Driver

■

525kHz/1.6MHz, Constant Current Boost and SEPIC LED Driver with

30038501

30038502

Connection Diagrams

LM3410

Top View

5–Pin SOT23

30038503

Top View

6-Pin LLP

Top View

30038504

8-Pin eMSOP

Ordering Information

Order Number Frequency Package Type Package Drawing Supplied As

LM3410YMF

LM3410YMFX 3000 units Tape & Reel

LM3410YMFE 250 units Tape & Reel

LM3410YSD

LM3410YSDX 4500 units Tape & Reel

LM3410YSDE 250 units Tape & Reel

LM3410YMY

LM3410YMYX 3500 units Tape & Reel

LM3410YMYE 250 units Tape & Reel

LM3410XMF

LM3410XMFX 3000 units Tape & Reel

LM3410XMFE 250 units Tape & Reel

LM3410XSD

LM3410XSDX 4500 units Tape & Reel

LM3410XSDE 250 units Tape & Reel

LM3410XMY

LM3410XMYX 3500 units Tape & Reel

LM3410XMYE 250 units Tape & Reel

525 kHz

1.6 MHz

SOT23-5 MF05A

LLP-6 SDE06A

eMSOP-8 MUY08A

SOT23-5 MF05A

LLP-6 SDE06A

eMSOP-8 MUY08A

1000 units Tape & Reel

1000 units tape & reel

1000 units Tape & Reel

30038505

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Pin Descriptions - 5-Pin SOT23

Pin Name Function

1 SW Output switch. Connect to the inductor, output diode.

2 GND

3 FB Feedback pin. Connect FB to external resistor divider to set output voltage.

4 DIM

5 VIN Supply voltage pin for power stage, and input supply voltage.

Signal and power ground pin. Place the bottom resistor of the feedback network as close as possible to this pin.

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 + 0.3V.

Pin Descriptions - 6-Pin LLP

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

4 FB Feedback pin. Connect FB to external resistor divider to set output voltage.

5 AGND

6 SW Output switch. Connect to the inductor, output diode.

DAP GND

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 + 0.3V.

Signal ground pin. Place the bottom resistor of the feedback network as close as possible to this pin & pin

Signal & Power ground. Connect to pin 1 & pin 5 on top layer. Place 4-6 vias from DAP to bottom layer GND plane.

LM3410

Pin Descriptions - 8-Pin eMSOP

Pin Name Function

1 - No Connect

2 PGND Power ground pin. Place PGND and output capacitor GND close together.

3 VIN Supply voltage for power stage, and input supply voltage.

4 DIM

5 FB Feedback pin. Connect FB to external resistor divider to set output voltage.

6 AGND Signal ground pin. Place the bottom resistor of the feedback network as close as possible to this pin & pin 5

7 SW Output switch. Connect to the inductor, output diode.

8 - No Connect

DAP GND

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 + 0.3V.

Signal & Power ground. Connect to pin 2 & pin 6 on top layer. Place 4-6 vias from DAP to bottom layer GND plane.

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Absolute Maximum Ratings (Note 1)

If Military/Aerospace specified devices are required,

LM3410

please contact the National Semiconductor Sales Office/ Distributors for availability and specifications.

SW Voltage -0.5V to 26.5V FB Voltage -0.5V to 3.0V DIM Voltage -0.5V to 7.0V ESD Susceptibility (Note 4) Human Body Model 2kV Junction Temperature (Note 2) 150°C

-0.5V to 7V

Storage Temp. Range -65°C to 150°C Soldering Information Infrared/Convection Reflow (15sec) 220°C

Operating Ratings (Note 1)

(Note 5) 0V to V

DIM

Junction Temperature Range -40°C to 125°C Power Dissipation

(Internal) SOT23-5 400 mW

2.7V to 5.5V

3V to 24V

Electrical Characteristics Limits in standard type are for T

= 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 guaranteed through test, design, or statistical correlation. Typical values represent the most likely parametric norm at TJ = 25°C, and are provided for reference purposes only. VIN = 5V, unless otherwise indicated under the Conditions column.

Symbol Parameter Conditions Min Typ Max Units

ΔVFB/V

MAX

MIN

DS(ON)

Feedback Voltage 178 190 202 mV

Feedback Voltage Line Regulation

VIN = 2.7V to 5.5V

- 0.06 - %/V

Feedback Input Bias Current - 0.1 1 µA

Switching Frequency

Maximum Duty Cycle

Minimum Duty Cycle

Switch On Resistance

LM3410-X 1200 1600 2000

LM3410-Y 360 525 680

LM3410-X 88 92 -

LM3410-Y 90 95 -

LM3410-X - 5 -

LM3410-Y - 2 -

SOT23-5 and eMSOP-8 - 170 330

LLP-6 190 350

Switch Current Limit 2.1 2.80 - A

kHz

mΩ

SU Start Up Time - 20 - µs

Quiescent Current (switching)

Quiescent Current (shutdown)

UVLO Undervoltage Lockout

DIM_H

DIM

Shutdown Threshold Voltage - - 0.4

Enable Threshold Voltage 1.8 - -

Switch Leakage

Dimming Pin Current Sink/Source - 100 - nA

LM3410-X VFB = 0.25

LM3410-Y VFB = 0.25

All Options V

DIM

= 0V

VIN Rising

VIN Falling

VSW = 24V

- 7.0 11

- 3.4 7

- 80 - nA

- 2.3 2.65

1.7 1.9 -

- 1.0 - µA

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Symbol Parameter Conditions Min Typ Max Units

Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is intended to be functional, but does not guarantee specific performance limits. For guaranteed specifications and conditions, see the Electrical Characteristics.

Note 2: Thermal shutdown will occur if the junction temperature exceeds the maximum junction temperature of the device.

Note 3: Applies for packages soldered directly onto a 3” x 3” PC board with 2oz. copper on 4 layers in still air.

Note 4: The human body model is a 100 pF capacitor discharged through a 1.5 kΩ resistor into each pin. Test method is per JESD22-A114.

Note 5: Do not allow this pin to float or be greater than VIN +0.3V.

Junction to Ambient 0 LFPM Air Flow (Note 3)

Junction to Case (Note 3)

Thermal Shutdown Temperature (Note 2) - 165 - °C

LLP-6 and eMSOP-8 Package - 80 -

SOT23-5 Package - 118 -

LLP-6 and eMSOP-8 Package - 18 -

SOT23-5 Package - 60 -

°C/W

LM3410

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Typical Performance Characteristics All curves taken at V

= 5.0V with configuration in typical

application circuit shown in Application Information section of this datasheet. TJ = 25C, unless otherwise specified.

LM3410

LM3410-X Efficiency vs VIN (R

SET

= 4Ω)

LM3410-X Start-Up Signature

30038502

4 x 3.3V LEDs 500 Hz DIM FREQ D = 50%

30038508

Current Limit vs Temperature

DIM Freq & Duty Cycle vs Avg I-LED

vs Temperature

DSON

30038507

30038509

30038510

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30038511

LM3410

Oscillator Frequency vs Temperature - "X"

30038512

VFB vs Temperature

Oscillator Frequency vs Temperature - "Y"

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30038580

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Simplified Internal Block Diagram

LM3410

FIGURE 1. Simplified Block Diagram

Application Information

THEORY OF OPERATION

The LM3410 is a constant frequency PWM, boost regulator IC. It delivers a minimum of 2.1A peak switch current. The device operates very similar to a voltage regulated boost converter except that it regulates the output current through LEDs. The current magnitude is set with a series resistor. This series resistor multiplied by the LED current creates the feedback voltage (190 mV) which the converter regulates to. The regulator has a preset switching frequency of either 525 kHz or 1.60 MHz. This high frequency allows the LM3410 to operate with small surface mount capacitors and inductors, resulting in a DC/DC converter that requires a minimum amount of board space. The LM3410 is internally compensated, so it is simple to use, and requires few external components. The LM3410 uses current-mode control to regulate the LED current. The following operating description of the LM3410 will refer to the Simplified Block Diagram (Figure 1) the simplified schematic (Figure 2), and its associated waveforms (Figure 3). The LM3410 supplies a regulated LED current by switching the internal NMOS control switch at constant frequency and variable duty cycle. A switching cycle

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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 control switch. During this on-time, the SW pin voltage (VSW) decreases to approximately GND, 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 sensed 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 V output switch turns off until the next switching cycle begins. During the switch off-time, inductor current discharges through diode D1, which forces the SW pin to swing to the output voltage plus the forward voltage (VD) of the diode. The regulator loop adjusts the duty cycle (D) to maintain a regulated LED current.

. When the PWM comparator output goes high, the

REF

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30038515

FIGURE 2. Simplified Boost Topology Schematic

LM3410

Design Guide

SETTING THE LED CURRENT

30038517

FIGURE 4. Setting I

LED

The LED current is set using the following equation:

where R

is connected between the FB pin and GND.

SET

DIM PIN / SHUTDOWN MODE

The average LED current can be controlled using a PWM signal on the DIM pin. The duty cycle can be varied between 0 & 100% to either increase or decrease LED brightness. PWM frequencies in the range of 1 Hz to 25 kHz can be used. For controlling LED currents down to the µA levels, it is best to use a PWM signal frequency between 200-1 kHz. The maximum LED current would be achieved using a 100% duty cycle, i.e. the DIM pin always high.

LED-DRIVE CAPABILITY

When using the LM3410 in the typical application configuration, with LEDs stacked in series between the VOUT and FB pin, the maximum number of LEDs that can be placed in series is dependent on the maximum LED forward voltage (VF

MAX

(VF

x N

MAX

When inserting a value for maximum VF voltage variation over the operating temperature range

) + 190 mV < 24V

LEDs

the LED forward

MAX

should be considered.

30038516

FIGURE 3. Typical Waveforms

CURRENT LIMIT

The LM3410 uses cycle-by-cycle current limiting to protect the internal NMOS switch. It is important to note that this current limit will not protect the output from excessive current during an output short circuit. The input supply is connected to the output by the series connection of an inductor and a diode. If a short circuit is placed on the output, excessive current can damage both the inductor and diode.

THERMAL SHUTDOWN

Thermal shutdown limits total power dissipation by turning off the output switch when the IC junction temperature exceeds 165°C. After thermal shutdown occurs, the output switch doesn’t turn on until the junction temperature drops to approximately 150°C.

INDUCTOR SELECTION

The inductor value determines the input ripple current. Lower inductor values decrease the physical size of the inductor, but increase the input ripple current. An increase in the inductor value will decrease the input ripple current.

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LM3410

From the previous equations, the inductor value is then obtained.

30038519

FIGURE 5. Inductor Current

The Duty Cycle (D) for a Boost converter can be approximated by using the ratio of output voltage (V (VIN).

) to input voltage

OUT

Therefore:

Power losses due to the diode (D1) forward voltage drop, the voltage drop across the internal NMOS switch, the voltage drop across the inductor resistance (R losses must be included to calculate a more accurate duty

) and switching

DCR

cycle (See Calculating Efficiency and Junction Tempera- ture for a detailed explanation). A more accurate formula for calculating the conversion ratio is:

Where η equals the efficiency of the LM3410 application. Or:

Therefore:

Where

1/TS = f

One must also ensure that the minimum current limit (2.1A) is not exceeded, so the peak current in the inductor must be calculated. The peak current (Lpk I) in the inductor is calculated by:

= IIN + ΔIL or I

Lpk

= I

OUT

/D' + Δi

When selecting an inductor, make sure that it is capable of supporting the peak input current without saturating. Inductor saturation will result in a sudden reduction in inductance and prevent the regulator from operating correctly. Because of the speed of the internal current limit, the peak current of the inductor need only be specified for the required maximum input current. For example, if the designed maximum input current is 1.5A and the peak current is 1.75A, then the inductor should be specified with a saturation current limit of >1.75A. There is no need to specify the saturation or peak current of the inductor at the 2.8A typical switch current limit.

Because of the operating frequency of the LM3410, 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 inductors see Example Circuits.

INPUT CAPACITOR

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, RMS current rating, and ESL (Equivalent Series Inductance). The recommended input capacitance is 2.2 µF to 22 µF depending on the application. The capacitor manufacturer specifically states the input voltage rating. 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 ESL of an input capacitor is usually determined by the effective cross sectional area of the current path. At the operating frequencies of the LM3410, certain capacitors may have an ESL so large that the resulting impedance (2πfL) will be higher than that required to provide stable operation. As a result, surface mount capacitors are strongly recommended. Multilayer ceramic capacitors (MLCC) are good choices for both input and output capacitors and have very low ESL. For MLCCs it is recommended to use X7R or X5R dielectrics. Consult capacitor manufacturer datasheet to see how rated capacitance varies over operating conditions.

Inductor ripple in a LED driver circuit can be greater than what would normally be allowed in a voltage regulator Boost & Sepic design. A good design practice is to allow the inductor to produce 20% to 50% ripple of maximum load. The increased ripple shouldn’t be a problem when illuminating LEDs.

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OUTPUT CAPACITOR

The LM3410 operates at frequencies allowing the use of ceramic output capacitors without compromising transient response. Ceramic capacitors allow higher inductor ripple without significantly increasing output ripple. The output capacitor is selected based upon the desired output ripple and transient response. The initial current of a load transient is provided mainly by the output capacitor. The output impedance will therefore determine the maximum voltage perturbation. The output ripple of the converter is a function

of the capacitor’s reactance and its equivalent series resistance (ESR):

When using MLCCs, the ESR is typically so low that the capacitive ripple may dominate. When this occurs, the output ripple will be approximately sinusoidal and 90° phase shifted from the switching action.

Given the availability and quality of MLCCs and the expected output voltage of designs using the LM3410, there is really no need to review any other capacitor technologies. Another benefit of ceramic capacitors is their ability to bypass high frequency noise. A certain amount of switching edge noise will couple through parasitic capacitances in the inductor to the output. A ceramic capacitor will bypass this noise while a tantalum will not. Since the output capacitor is one of the two external components that control the stability of the regulator control loop, most applications will require a minimum at 0.47 µF of output capacitance. Like the input capacitor, recommended multilayer ceramic capacitors are X7R or X5R. Again, verify actual capacitance at the desired operating voltage and temperature.

DIODE

The diode (D1) conducts during the switch off time. A Schottky diode is recommended for its fast switching times and low forward voltage drop. The diode should be chosen so that its current rating is greater than:

ID1 ≥ I

OUT

The reverse breakdown rating of the diode must be at least the maximum output voltage plus appropriate margin.

OUTPUT OVER-VOLTAGE PROTECTION

A simple circuit consisting of an external zener diode can be implemented to protect the output and the LM3410 device from an over-voltage fault condition. If an LED fails open, or is connected backwards, an output open circuit condition will occur. No current is conducted through the LED’s, and the feedback node will equal zero volts. The LM3410 will react to this fault by increasing the duty-cycle, thinking the LED current has dropped. A simple circuit that protects the LM3410 is shown in figure 6.

Zener diode D2 and resistor R3 is placed from V with the string of LEDs. If the output voltage exceeds the

in parallel

OUT

breakdown voltage of the zener diode, current is drawn through the zener diode, R3 and sense resistor R1. Once the voltage across R1 and R3 equals the feedback voltage of 190mV, the LM3410 will limit its duty-cycle. No damage will occur to the LM3410, the LED’s, or the zener diode. Once the fault is corrected, the application will work as intended.

30038530

FIGURE 6. Overvoltage Protection Circuit

PCB Layout Considerations

When planning layout there are a few things to consider when trying to achieve a clean, regulated output. The most important consideration when completing a Boost Converter layout is the close coupling of the GND connections of the C pacitor and the LM3410 PGND pin. The GND ends should be close to one another and be connected to the GND plane with at least two through-holes. 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 and inaccurate regulation. The R possible to the IC, with the AGND of R as possible to the AGND (pin 5 for the LLP) of the IC. Radiated

feedback resistor should be placed as close as

SET

(R1) placed as close

SET

noise can be decreased by choosing a shielded inductor. The remaining components should also be placed as close as possible to the IC. Please see Application Note AN-1229 for further considerations and the LM3410 demo board as an example of a four-layer layout.

Below is an example of a good thermal & electrical PCB design.

30038532

OUT

ca-

LM3410

FIGURE 7. Boost PCB Layout Guidelines

This is very similar to our LM3410 demonstration boards that are obtainable via the National Semiconductor website. The demonstration board consists of a two layer PCB with a common input and output voltage application. Most of the routing is on the top layer, with the bottom layer consisting of a large ground plane. The placement of the external components satisfies the electrical considerations, and the thermal perfor-

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mance has been improved by adding thermal vias and a top layer “Dog-Bone”.

LM3410

For certain high power applications, the PCB land may be modified to a "dog bone" shape (see Figure 8). Increasing the size of ground plane and adding thermal vias can reduce the R

for the application.

θJA

30038533

FIGURE 8. PCB Dog Bone Layout

Thermal Design

When designing for thermal performance, one must consider many variables:

Ambient Temperature: The surrounding maximum air temperature is fairly explanatory. As the temperature increases, the junction temperature will increase. This may not be linear though. As the surrounding air temperature increases, resistances of semiconductors, wires and traces increase. This will decrease the efficiency of the application, and more power will be converted into heat, and will increase the silicon junction temperatures further.

Forced Airflow: Forced air can drastically reduce the device junction temperature. Air flow reduces the hot spots within a design. Warm airflow is often much better than a lower ambient temperature with no airflow.

External Components: Choose components that are efficient, and you can reduce the mutual heating between devices.

PCB design with thermal performance in mind:

The PCB design is a very important step in the thermal design procedure. The LM3410 is available in three package options (5 pin SOT23, 8 pin eMSOP & 6 pin LLP). The options are electrically the same, but difference between the packages is size and thermal performance. The LLP and eMSOP have thermal Die Attach Pads (DAP) attached to the bottom of the packages, and are therefore capable of dissipating more heat than the SOT23 package. It is important that the customer choose the correct package for the application. A detailed thermal design procedure has been included in this data sheet. This procedure will help determine which package is correct, and common applications will be analyzed.

There is one significant thermal PCB layout design consideration that contradicts a proper electrical PCB layout design

consideration. This contradiction is the placement of external components that dissipate heat. The greatest external heat contributor is the external Schottky diode. It would be nice if you were able to separate by distance the LM3410 from the Schottky diode, and thereby reducing the mutual heating effect. This will however create electrical performance issues. It is important to keep the LM3410, the output capacitor, and Schottky diode physically close to each other (see PCB layout guidelines). The electrical design considerations outweigh the thermal considerations. Other factors that influence thermal performance are thermal vias, copper weight, and number of board layers.

Thermal Definitions

Heat energy is transferred from regions of high temperature to regions of low temperature via three basic mechanisms: radiation, conduction and convection.

Radiation: Electromagnetic transfer of heat between masses at different temperatures.

Conduction: Transfer of heat through a solid medium. Convection: Transfer of heat through the medium of a fluid;

typically air.

Conduction & Convection will be the dominant heat transfer mechanism in most applications.

: Thermal impedance from silicon junction to ambient air

θJA

temperature. R

: Thermal impedance from silicon junction to device case

θJC

temperature. C

: Thermal Delay from silicon junction to device case tem-

θJC

perature. C

: Thermal Delay from device case to ambient air tem-

θCA

perature. R

& R

θJA

impedances, and most data sheets contain associated values

: These two symbols represent thermal

θJC

for these two symbols. The units of measurement are °C/ Watt.

is the sum of smaller thermal impedances (see simplified

θJA

thermal model Figures 9 and 10). Capacitors within the model represent delays that are present from the time that power and its associated heat is increased or decreased from steady state in one medium until the time that the heat increase or decrease reaches steady state in the another medium.

The datasheet values for these symbols are given so that one might compare the thermal performance of one package against another. To achieve a comparison between packages, all other variables must be held constant in the comparison (PCB size, copper weight, thermal vias, power dissipation, VIN, V on the package performance, but it would be a mistake to use

, load current etc). This does shed light

OUT

these values to calculate the actual junction temperature in your application.

LM3410 Thermal Models

Heat is dissipated from the LM3410 and other devices. The external loss elements include the Schottky diode, inductor, and loads. All loss elements will mutually increase the heat on the PCB, and therefore increase each other’s temperatures.

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FIGURE 9. Thermal Schematic

LM3410

30038534

FIGURE 10. Associated Thermal Model

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30038535

Calculating Efficiency, and Junction Temperature

LM3410

We will talk more about calculating proper junction temperature with relative certainty in a moment. For now we need to describe how to calculate the junction temperature and clarify some common misconceptions.

A common error when calculating R package is the only variable to consider.

[variables]:

θJA

•

Input Voltage, Output Voltage, Output Current, R

•

Ambient temperature & air flow

•

Internal & External components power dissipation

•

Package thermal limitations

•

PCB variables (copper weight, thermal via’s, layers component placement)

Another common error when calculating junction temperature is to assume that the top case temperature is the proper temperature when calculating R impedance of all six sides of a package, not just the top side.

θJC

This document will refer to a thermal impedance called

represents a thermal impedance associated with just the top case temperature. This will allow one to calculate the junction temperature with a thermal sensor connected to the top case.

The complete LM3410 Boost converter efficiency can be calculated in the following manner.

is to assume that the

θJA

. R

represents the thermal

θJC

DS(ON)

One can see that if the loss elements are reduced to zero, the conversion ratio simplifies to:

And we know:

Therefore:

Calculations for determining the most significant power losses are discussed below. Other losses totaling less than 2% are not discussed.

A simple efficiency calculation that takes into account the conduction losses is shown below:

Power loss (P converter, switching and conduction. Conduction losses usu-

) is the sum of two types of losses in the

LOSS

ally dominate at higher output loads, where as switching losses remain relatively fixed and dominate at lower output loads.

Losses in the LM3410 Device: P

LOSS

= P

COND

+ PSW + P

Where PQ = quiescent operating power loss Conversion ratio of the Boost Converter with conduction loss

elements inserted:

Where R

= Inductor series resistance

DCR

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The diode, NMOS switch, and inductor DCR losses are included in this calculation. Setting any loss element to zero will simplify the equation.

VD is the forward voltage drop across the Schottky diode. It can be obtained from the manufacturer’s Electrical Characteristics section of the data sheet.

The conduction losses in the diode are calculated as follows:

= VD x I

DIODE

LED

Depending on the duty cycle, this can be the single most significant power loss in the circuit. Care should be taken to choose a diode that has a low forward voltage drop. Another concern with diode selection is reverse leakage current. Depending on the ambient temperature and the reverse voltage across the diode, the current being drawn from the output to the NMOS switch during time D could be significant, this may increase losses internal to the LM3410 and reduce the overall efficiency of the application. Refer to Schottky diode manufacturer’s data sheets for reverse leakage specifications, and typical applications within this data sheet for diode selections.

Another significant external power loss is the conduction loss in the input inductor. The power loss within the inductor can be simplified to:

= I

DCR

IND

The LM3410 conduction loss is mainly associated with the internal power switch:

COND-NFET

= I

SW-rms

x R

DSON

x D

30038542

FIGURE 11. LM3410 Switch Current

(small ripple approximation)

COND-NFET

= I

x R

DSON

x D

The value for R junction temperature you wish to analyze. As an example, at 125°C and R

should be equal to the resistance at the

DSON

= 250 mΩ (See typical graphs for value).

DSON

Switching losses are also associated with the internal power switch. They occur during the switch on and off transition periods, where voltages and currents overlap resulting in power loss.

The simplest means to determine this loss is to empirically measuring the rise and fall times (10% to 90%) of the switch at the switch node:

SWR

SWF

= 1/2(V

PSW = P

x IIN x fSW x t

OUT

x IIN x fSW x t

OUT

+ P

SWR

SWF

RISE

FALL

)

Typical Switch-Node Rise and Fall Times

OUT

RISE

FALL

3V 5V 6nS 4nS

5V 12V 6nS 5nS

3V 12V 8nS 7nS

5V 18V 10nS 8nS

Quiescent Power Losses

IQ is the quiescent operating current, and is typically around

1.5 mA.

Power Loss

SET

PQ = IQ x V

Example Efficiency Calculation:

Operating Conditions: 5 x 3.3V LEDs + 190mV

TABLE 1. Operating Conditions

OUT

LED

RISE

FALL

DSON

DCR

D 0.82

ΣP

+ PSW + P

COND

Quiescent Power Loss:

PQ = IQ x VIN = 10 mW

Switching Power Loss:

= 1/2(V

SWR

= 1/2(V

SWF

PSW = P

Internal NFET Power Loss:

CONDUCTION

Diode Loss:

VD = 0.45V

DIODE

Inductor Power Loss:

= 75 mΩ

DCR

IND

≊ 16.7V

REF

DIODE

x IIN x fSW x t

OUT

x IIN x fSW x t

OUT

+ P

SWR

= 225 mΩ

DSON

x D x R

= I

IIN = 310 mA

= VD x I

x R

= I

+ P

= 80 mW

SWF

= 23 mW

LED

= 7 mW

DCR

+ PQ = P

IND

RISE

FALL

DSON

3.3V

16.7V

50mA

0.45V

1.60MHz

3mA

10nS

225mΩ

75mΩ

0.31A

LOSS

) ≊ 40 mW

= 17 mW

LM3410

15 www.national.com

Total Power Losses are:

LM3410

TABLE 2. Power Loss Tabulation

OUT

LED

RISE

DSON

DCR

3.3V

16.7V

50mA P

0.45V P

1.6MHz

10nS P

3mA P

225mΩ

75mΩ

DIODE

COND

OUT

SWR

SWF

IND

D 0.82

85% P

LOSS

INTERNAL

= P

+ PSW = 107 mW

COND

Calculating and

We now know the internal power dissipation, and we are trying to keep the junction temperature at or below 125°C. The next step is to calculate the value for and/or . This is actually very simple to accomplish, and necessary if you think you may be marginal with regards to thermals or determining what package option is correct.

The LM3410 has a thermal shutdown comparator. When the silicon reaches a temperature of 165°C, the device shuts down until the temperature drops to 150°C. Knowing this, one can calculate the or the of a specific application. Because the junction to top case thermal impedance is much lower than the thermal impedance of junction to ambient air, the error in calculating is lower than for . However, you will need to attach a small thermocouple onto the top case of the LM3410 to obtain the value.

Knowing the temperature of the silicon when the device shuts down allows us to know three of the four variables. Once we calculate the thermal impedance, we then can work backwards with the junction temperature set to 125°C to see what maximum ambient air temperature keeps the silicon below the 125°C temperature.

Procedure:

Place your application into a thermal chamber. You will need to dissipate enough power in the device so you can obtain a good thermal impedance value.

Raise the ambient air temperature until the device goes into thermal shutdown. Record the temperatures of the ambient air and/or the top case temperature of the LM3410. Calculate the thermal impedances.

Example from previous calculations (SOT23-5 Package): P TA @ Shutdown = 155°C TC @ Shutdown = 159°C

INTERNAL

= 107 mW

825W

23mW

40mW

10mW

17mW

7mW

137mW

SOT23-5 = 93°C/W

SOT23-5 = 56°C/W

Typical LLP & eMSOP typical applications will produce numbers in the range of 50°C/W to 65°C/W, and will vary between 18°C/W and 28°C/W. These values are for PCB’s with two and four layer boards with 0.5 oz copper, and four to six thermal vias to bottom side ground plane under the DAP. The thermal impedances calculated above are higher due to the small amount of power being dissipated within the device.

Note: To use these procedures it is important to dissipate an amount of power within the device that will indicate a true thermal impedance value. If one uses a very small internal dissipated value, one can see that the thermal impedance calculated is abnormally high, and subject to error. Figure 12 shows the nonlinear relationship of internal power dissipation vs .

30038551

FIGURE 12. R

For 5-pin SOT23 package typical applications, R will range from 80°C/W to 110°C/W, and will vary between

vs Internal Dissipation

θJA

numbers

θJA

50°C/W and 65°C/W. These values are for PCB’s with two & four layer boards with 0.5 oz copper, with two to four thermal vias from GND pin to bottom layer.

Here is a good rule of thumb for typical thermal impedances, and an ambient temperature maximum of 75°C: If your design requires that you dissipate more than 400mW internal to the LM3410, or there is 750mW of total power loss in the application, it is recommended that you use the 6 pin LLP or the 8 pin eMSOP package with the exposed DAP.

SEPIC Converter

The LM3410 can easily be converted into a SEPIC converter. A SEPIC converter has the ability to regulate an output voltage that is either larger or smaller in magnitude than the input voltage. Other converters have this ability as well (CUK and Buck-Boost), but usually create an output voltage that is opposite in polarity to the input voltage. This topology is a perfect fit for Lithium Ion battery applications where the input voltage for a single cell Li-Ion battery will vary between 2.7V & 4.5V and the output voltage is somewhere in between. Most of the

www.national.com 16

LM3410

analysis of the LM3410 Boost Converter is applicable to the LM3410 SEPIC Converter.

SEPIC Design Guide:

SEPIC Conversion ratio without loss elements:

Therefore:

Small ripple approximation:

In a well-designed SEPIC converter, the output voltage, and input voltage ripple, the inductor ripple IL1 and IL2 is small in comparison to the DC magnitude. Therefore it is a safe approximation to assume a DC value for these components. The main objective of the Steady State Analysis is to determine the steady state duty-cycle, voltage and current stresses on all components, and proper values for all components.

In a steady-state converter, the net volt-seconds across an inductor after one cycle will equal zero. Also, the charge into a capacitor will equal the charge out of a capacitor in one cycle.

Therefore:

The average inductor current of L2 is the average output load.

30038556

FIGURE 13. Inductor Volt-Sec Balance Waveform

Applying Charge balance on C1:

Since there are no DC voltages across either inductor, and capacitor C3 is connected to Vin through L1 at one end, or to ground through L2 on the other end, we can say that

VC3 = V

Therefore:

Substituting IL1 into I

This verifies the original conversion ratio equation. It is important to remember that the internal switch current is

equal to IL1 and IL2 during the D interval. Design the converter

IL2 = I

LED

so that the minimum guaranteed peak switch current limit (2.1A) is not exceeded.

30038552

FIGURE 14. HB/OLED SEPIC CONVERTER Schematic

17 www.national.com

Steady State Analysis with Loss Elements

LM3410

30038559

FIGURE 15. SEPIC Simplified Schematic

Using inductor volt-second balance & capacitor charge balance, the following equations are derived:

IL2 = (I

LED

)

and

IL1 = (I

) x (D/D')

LED

Therefore:

One can see that all variables are known except for the duty cycle (D). A quadratic equation is needed to solve for D. A less accurate method of determining the duty cycle is to assume efficiency, and calculate the duty cycle.

TABLE 3. Efficiencies for Typical SEPIC Applications

OUT

LED

2.7V V

3.1V V

770mA I

500mA I

75%

OUT

LED

3.3V V

3.1V V

600mA I

500mA I

80%

OUT

LED

3.1V

375mA

500mA

83%

SEPIC Converter PCB Layout

The layout guidelines described for the LM3410 Boost-Converter are applicable to the SEPIC OLED Converter. Figure 16 is a proper PCB layout for a SEPIC Converter.

www.national.com 18

30038565

FIGURE 16. HB/OLED SEPIC PCB Layout

LM3410X SOT23-5 Design Example 1: 5 x 1206 Series LED String Application

LM3410

LM3410X (1.6MHz): VIN = 2.7V to 5.5V, 5 x 3.3V LEDs, (V

Part ID Part Value Manufacturer Part Number

U1 2.8A ISW LED Driver NSC LM3410XMF

C1, Input Cap 10µF, 6.3V, X5R TDK C2012X5R0J106M

C2 Output Cap 2.2µF, 25V, X5R TDK C2012X5R1E225M

D1, Catch Diode 0.4Vf Schottky 500mA, 30V

L1 10µH 1.2A Coilcraft DO1608C-103

LED's

SMD-1206, 50mA, Vf ≊ 3 .6V

4.02Ω, 1%

100kΩ, 1%

Diodes Inc MBR0530

≊ 16.5V) I

OUT

Vishay CRCW08054R02F

Vishay CRCW08051003F

Lite-On LTW-150k

≊ 50mA

LED

30038581

19 www.national.com

LM3410Y SOT23-5 Design Example 2: 5 x 1206 Series LED String Application

LM3410

LM3410Y (550kHz): VIN = 2.7V to 5.5V, 5 x 3.3V LEDs, (V

Part ID Part Value Manufacturer Part Number

U1 2.8A ISW LED Driver NSC LM3410YMF

C1, Input Cap 10µF, 6.3V, X5R TDK C2012X5R0J106M

C2 Output Cap 2.2µF, 25V, X5R TDK C2012X5R1E225M

D1, Catch Diode 0.4Vf Schottky 500mA, 30V

L1 15µH 1.2A Coilcraft DO1608C-153

LED's

SMD-1206, 50mA, Vf ≊ 3 .6V

4.02Ω, 1%

100kΩ, 1%

Diodes Inc MBR0530

≊ 16.5V) I

OUT

Vishay CRCW08054R02F

Vishay CRCW08051003F

Lite-On LTW-150k

≊ 50mA

LED

30038581

www.national.com 20

LM3410X LLP-6 Design Example 3: 7 LEDs x 5 LED String Backlighting Application

LM3410

LM3410X (1.6MHz): VIN = 2.7V to 5.5V, 7 x 5 x 3.3V LEDs, (V

Part ID Part Value Manufacturer Part Number

U1 2.8A ISW LED Driver NSC LM3410XSD

C1, Input Cap 10µF, 6.3V, X5R TDK C2012X5R0J106M

C2 Output Cap 4.7µF, 25V, X5R TDK C2012X5R1E475M

D1, Catch Diode 0.4Vf Schottky 500mA, 30V

L1 8.2µH, 2A Coilcraft MSS6132-822ML

LED's

SMD-1206, 50mA, Vf ≊ 3 .6V

1.15Ω, 1%

100kΩ, 1%

Diodes Inc MBR0530

Vishay CRCW08051R15F

Vishay CRCW08051003F

Lite-On LTW-150k

≊ 16.7V), I

OUT

≊ 25mA

LED

300385a2

21 www.national.com

LM3410X LLP-6 Design Example 4: 3 x HB LED String Application

LM3410

LM3410X (1.6MHz): VIN = 2.7V to 5.5V, 3 x 3.4V LEDs, (V

Part ID Part Value Manufacturer Part Number

U1 2.8A ISW LED Driver NSC LM3410XSD

C1, Input Cap 10µF, 6.3V, X5R TDK C2012X5R0J106M

C2 Output Cap 2.2µF, 25V, X5R TDK C2012X5R1E225M

D1, Catch Diode 0.4Vf Schottky 500mA, 30V

L1 10µH 1.2A Coilcraft DO1608C-103

HB - LED's

1.00Ω, 1%

100kΩ, 1%

1.50Ω, 1%

340mA, Vf ≊ 3 .6V

Diodes Inc MBR0530

≊ 11V) I

OUT

Vishay CRCW08051R00F

Vishay CRCW08051003F

Vishay CRCW08051R50F

CREE XREWHT-L1-0000-0901

≊ 340mA

LED

30038567

www.national.com 22

LM3410Y SOT23-5 Design Example 5: 5 x 1206 Series LED String Application with OVP

LM3410

LM3410Y (525kHz): VIN = 2.7V to 5.5V, 5 x 3.3V LEDs, (V

Part ID Part Value Manufacturer Part Number

U1 2.8A ISW LED Driver NSC LM3410YMF

C1 Input Cap 10µF, 6.3V, X5R TDK C2012X5R0J106M

C2 Output Cap 2.2µF, 25V, X5R TDK C2012X5R1E225M

D1, Catch Diode 0.4Vf Schottky 500mA, Diodes Inc MBR0530

D2 18V Zener diode Diodes Inc 1N4746A

L1 15µH, 0.70A TDK VLS4012T-150MR65

LED’s

SMD-1206, 50mA, Vf ≊ 3 .6V

4.02Ω, 1%

100kΩ, 1%

≊ 16.5V) I

OUT

Vishay CRCW08054R02F

Vishay CRCW08051003F

Vishay CRCW06031000F

Lite-On LTW-150k

≊ 50mA

LED

30038568

23 www.national.com

LM3410X SEPIC LLP-6 Design Example 6: HB/OLED Illumination Application

LM3410

LM3410X (1.6MHz): VIN = 2.7V to 5.5V, (V

Part ID Part Value Manufacturer Part Number

U1 2.8A ISW LED Driver NSC LM3410XSD

C1 Input Cap 10µF, 6.3V, X5R TDK C2012X5R0J106K

C2 Output Cap 10µF, 6.3V, X5R TDK C2012X5R0J106K

C3 Cap 2.2µF, 25V, X5R TDK C2012X5R1E225M

D1, Catch Diode 0.4Vf, Schottky 1A, 20V

L1 & L2 4.7µH 3A Coilcraft MSS6132-472

HB - LED’s

665 mΩ, 1%

100kΩ, 1%

350mA, Vf ≊ 3 .6V

≊ 3.8V) I

OUT

Diodes Inc DFLS120L

Vishay CRCW0805R665F

Vishay CRCW08051003F

CREE XREWHT-L1-0000-0901

≊ 300mA

LED

30038552

www.national.com 24

LM3410X LLP-6 Design Example 7: Boost Flash Application

LM3410

LM3410X (1.6MHz): VIN = 2.7V to 5.5V, (V

OUT

≊ 8V) I

≊ 1.0A Pulsed

LED

30038570

Part ID Part Value Manufacturer Part Number

U1 2.8A ISW LED Driver NSC LM3410XSD

C1 Input Cap 10µF, 6.3V, X5R TDK C2012X5R0J106M

C2 Output Cap 10µF,16V, X5R TDK C2012X5R1A106M

D1, Catch Diode 0.4Vf Schottky 500mA, 30V

Diodes Inc MBR0530

L1 4.7µH, 3A Coilcraft MSS6132-472

LED’s

200mΩ, 1%

500mA, Vf ≊ 3 .6V, I

PULSE

= 1.0A

Vishay CRCW0805R200F

CREE XREWHT-L1-0000-0901

25 www.national.com

LM3410X SOT23-5 Design Example 8: 5 x 1206 Series LED String Application with VIN > 5.5V

LM3410

LM3410X (1.6MHz): V

= 9V to 14V, (V

PWR

≊ 16.5V) I

OUT

≊ 50mA

LED

30038571

Part ID Part Value Mfg Part Number

U1 2.8A ISW LED Driver NSC LM3410XMF

C1 Input V

Cap 10µF, 6.3V, X5R TDK C2012X5R0J106M

PWR

C2 Output Cap 2.2µF, 25V, X5R TDK C2012X5R1E225M

C2 Input VIN Cap 0.1µF, 6.3V, X5R TDK C1005X5R1C104K

D1, Catch Diode 0.43Vf, Schotky, 0.5A, 30V

Diodes Inc MBR0530

L1 10µH 1.2A Coilcraft DO1608C-103

4.02Ω, 1%

100kΩ, 1%

576Ω, 1%

Vishay CRCW08054R02F

Vishay CRCW08051003F

Vishay CRCW08055760F

D2 3.3V Zener, SOT23 Diodes Inc BZX84C3V3

LED’s

SMD-1206, 50mA, Vf ≊ 3 .6V

Lite-On LTW-150k

www.national.com 26

LM3410X LLP-6 Design Example 9: Camera Flash or Strobe Circuit Application

LM3410

LM3410X (1.6MHz): VIN = 2.7V to 5.5, (V

≊ 7.5V), I

OUT

≊ 1.5A Flash

LED

30038572

Part ID Part Value Mfg Part Number

U1 2.8A ISW LED Driver NSC LM3410XSD

C1 Input V

Cap 10µF, 6.3V, X5R TDK C1608X5R0J106K

PWR

C2 Output Cap 220µF, 10V, Tanatalum KEMET T491V2271010A2

C3 Cap 10µF, 16V, X5R TDK C3216X5R0J106K

D1, Catch Diode 0.43Vf, Schotky, 1.0A, 20V

Diodes Inc DFLS120L

L1 3.3µH 2.7A Coilcraft MOS6020-332

1.0kΩ, 1%

37.4kΩ, 1%

100kΩ, 1%

0.15Ω, 1%

Vishay CRCW08051001F

Vishay CRCW08053742F

Vishay CRCW08051003F

Vishay CRCW0805R150F

Q1, Q2 30V, ID = 3.9A ZETEX ZXMN3A14F

LED’s

500mA, Vf ≊ 3 .6V, I

PULSE

= 1.5A

CREE XREWHT-L1-0000-00901

27 www.national.com

LM3410X SOT23-5 Design Example 10: 5 x 1206 Series LED String Application with VIN & V

LM3410

Rail > 5.5V

PWR

LM3410X (1.6MHz): V

= 9V to 14V, VIN = 2.7V to 5.5V, (V

PWR

OUT

≊ 14V) I

≊ 50mA

LED

30038573

Part ID Part Value Mfg Part Number

U1 2.8A ISW LED Driver NSC LM3410XMF

C1 Input V

C2 V

Cap 10µF, 6.3V, X5R TDK C2012X5R0J106M

PWR

Cap 2.2µF, 25V, X5R TDK C2012X5R1E225M

OUT

C3 Input VIN Cap 0.1µF, 6.3V, X5R TDK C1005X5R1C104K

D1, Catch Diode 0.43Vf, Schotky, 0.5A, 30V

Diodes Inc MBR0530

L1 10µH 1.5A Coilcraft DO1608C-103

LED’s

4.02Ω, 1%

100kΩ, 1%

SMD-1206, 50mA, Vf ≊ 3 .6V

Vishay CRCW08054R02F

Vishay CRCW08051003F

Lite-On LTW-150k

www.national.com 28

LM3410X LLP-6 Design Example 11: Boot-Strap Circuit to Extended Battery Life

LM3410

LM3410X (1.6MHz): VIN = 1.9V to 5.5V, VIN > 2.3V (TYP) for Start Up

Part ID Part Value Mfg Part Number

U1 2.8A ISW LED Driver NSC LM3410XSD

C1 Input V

C2 V

C3 Input VIN Cap 0.1µF, 6.3V, X5R TDK C1005X5R1C104K

D1, Catch Diode 0.43Vf, Schotky, 1.0A, 20V

D2, D3 Dual Small Signal Schotky Diodes Inc BAT54CT

HB/OLED 3.4Vf, 350mA TT Electronics/Optek OVSPWBCR44

Cap 10µF, 6.3V, X5R TDK C1608X5R0J106K

PWR

Cap 10µF, 6.3V, X5R TDK C1608X5R0J106K

OUT

L1, L2 3.3µH 3A Coilcraft MOS6020-332

665 mΩ, 1%

100kΩ, 1%

Diodes Inc DFLS120L

Vishay CRCW0805R665F

Vishay CRCW08051003F

30038574

29 www.national.com

Physical Dimensions inches (millimeters) unless otherwise noted

LM3410

6-Lead LLP Package

NS Package Number SDE06A

5-Lead SOT23-5 Package

NS Package Number MF05A

www.national.com 30

LM3410

8-Lead eMSOP Package

NS Package Number MUY08A

31 www.national.com

Notes

For more National Semiconductor product information and proven design tools, visit the following Web sites at:

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Internal Compensation

Ethernet www.national.com/ethernet Packaging www.national.com/packaging

Interface www.national.com/interface Quality and Reliability www.national.com/quality

LVDS www.national.com/lvds Reference Designs www.national.com/refdesigns

Power Management www.national.com/power Feedback www.national.com/feedback

Switching Regulators www.national.com/switchers

LDOs www.national.com/ldo

LED Lighting www.national.com/led

PowerWise www.national.com/powerwise

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525kHz/1.6MHz, Constant Current Boost and SEPIC LED Driver with

LM3410 PowerWise

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National Semiconductor LM3410 Technical data

Specifications and Main Features

Frequently Asked Questions

User Manual

General Description

Typical Boost Application Circuit

Features

Applications

Connection Diagrams

Ordering Information

Pin Descriptions - 5-Pin SOT23

Pin Descriptions - 6-Pin LLP

Pin Descriptions - 8-Pin eMSOP

Absolute Maximum Ratings (Note 1)

Operating Ratings (Note 1)

Electrical Characteristics Limits in standard type are for T

Typical Performance Characteristics All curves taken at V

Simplified Internal Block Diagram

FIGURE 1. Simplified Block Diagram

Application Information

THEORY OF OPERATION

FIGURE 2. Simplified Boost Topology Schematic

Design Guide

SETTING THE LED CURRENT

DIM PIN / SHUTDOWN MODE

LED-DRIVE CAPABILITY

FIGURE 3. Typical Waveforms

CURRENT LIMIT

THERMAL SHUTDOWN

INDUCTOR SELECTION

FIGURE 5. Inductor Current

INPUT CAPACITOR

OUTPUT CAPACITOR

DIODE

OUTPUT OVER-VOLTAGE PROTECTION

FIGURE 6. Overvoltage Protection Circuit

PCB Layout Considerations

FIGURE 7. Boost PCB Layout Guidelines

FIGURE 8. PCB Dog Bone Layout

Thermal Design

Thermal Definitions

LM3410 Thermal Models

FIGURE 9. Thermal Schematic

FIGURE 10. Associated Thermal Model

Calculating Efficiency, and Junction Temperature

FIGURE 11. LM3410 Switch Current

Typical Switch-Node Rise and Fall Times

Example Efficiency Calculation:

TABLE 1. Operating Conditions

TABLE 2. Power Loss Tabulation

Calculating and

SEPIC Converter

FIGURE 13. Inductor Volt-Sec Balance Waveform

FIGURE 14. HB/OLED SEPIC CONVERTER Schematic

Steady State Analysis with Loss Elements

FIGURE 15. SEPIC Simplified Schematic

TABLE 3. Efficiencies for Typical SEPIC Applications

SEPIC Converter PCB Layout

FIGURE 16. HB/OLED SEPIC PCB Layout

LM3410X SOT23-5 Design Example 1: 5 x 1206 Series LED String Application

LM3410Y SOT23-5 Design Example 2: 5 x 1206 Series LED String Application

LM3410X LLP-6 Design Example 3: 7 LEDs x 5 LED String Backlighting Application

LM3410X LLP-6 Design Example 4: 3 x HB LED String Application

LM3410Y SOT23-5 Design Example 5: 5 x 1206 Series LED String Application with OVP

LM3410X SEPIC LLP-6 Design Example 6: HB/OLED Illumination Application

LM3410X LLP-6 Design Example 7: Boost Flash Application

LM3410X SOT23-5 Design Example 8: 5 x 1206 Series LED String Application with VIN > 5.5V

LM3410X LLP-6 Design Example 9: Camera Flash or Strobe Circuit Application

LM3410X LLP-6 Design Example 11: Boot-Strap Circuit to Extended Battery Life

Physical Dimensions inches (millimeters) unless otherwise noted