JAJSAX0H October   2007  – August 2016 LM3410 , LM3410-Q1

PRODUCTION DATA.  

  1. 特長
  2. アプリケーション
  3. 概要
  4. 改訂履歴
  5. Pin Configuration and Functions
  6. Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 ESD Ratings
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information
    5. 6.5 Electrical Characteristics
    6. 6.6 Typical Characteristics
  7. Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Current Limit
      2. 7.3.2 DIM Pin and Shutdown Mode
    4. 7.4 Device Functional Modes
      1. 7.4.1 Thermal Shutdown
  8. Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1 Boost Converter
        1. 8.1.1.1 Setting the LED Current
        2. 8.1.1.2 LED-Drive Capability
        3. 8.1.1.3 Inductor Selection
        4. 8.1.1.4 Input Capacitor
        5. 8.1.1.5 Output Capacitor
        6. 8.1.1.6 Diode
        7. 8.1.1.7 Output Overvoltage Protection
      2. 8.1.2 SEPIC Converter
        1. 8.1.2.1 SEPIC Equations
        2. 8.1.2.2 Steady State Analysis with Loss Elements
          1. 8.1.2.2.1 Details
    2. 8.2 Typical Applications
      1. 8.2.1  Low Input Voltage, 1.6-MHz, 3 to 5 White LED Output at 50-mA Boost Converter
        1. 8.2.1.1 Design Requirements
        2. 8.2.1.2 Detailed Design Procedure
          1. 8.2.1.2.1 Set the LED Current (R1)
          2. 8.2.1.2.2 Calculate Maximum Duty Cycle (DMAX)
          3. 8.2.1.2.3 Calculate the Inductor Value (L1)
          4. 8.2.1.2.4 Calculate the Output Capacitor (C2)
          5. 8.2.1.2.5 Input Capacitor (C1) and Schottky Diode (D1)
        3. 8.2.1.3 Application Curves
      2. 8.2.2  LM3410X SOT-23: 5 × 1206 Series LED String Application
        1. 8.2.2.1 Design Requirements
      3. 8.2.3  LM3410Y SOT-23: 5 × 1206 Series LED String Application
        1. 8.2.3.1 Design Requirements
      4. 8.2.4  LM3410X WSON: 7 × 5 LED Strings Backlighting Application
        1. 8.2.4.1 Design Requirements
      5. 8.2.5  LM3410X WSON: 3 × HB LED String Application
        1. 8.2.5.1 Design Requirements
      6. 8.2.6  LM3410Y SOT-23: 5 × 1206 Series LED String Application With OVP
        1. 8.2.6.1 Design Requirements
      7. 8.2.7  LM3410X SEPIC WSON: HB or OLED Illumination Application
        1. 8.2.7.1 Design Requirements
      8. 8.2.8  LM3410X WSON: Boost Flash Application
        1. 8.2.8.1 Design Requirements
      9. 8.2.9  LM3410X SOT-23: 5 × 1206 Series LED String Application With VIN > 5.5 V
        1. 8.2.9.1 Design Requirements
      10. 8.2.10 LM3410X WSON: Camera Flash or Strobe Circuit Application
        1. 8.2.10.1 Design Requirements
      11. 8.2.11 LM3410X SOT-23: 5 × 1206 Series LED String Application With VIN and VPWR Rail > 5.5 V
        1. 8.2.11.1 Design Requirements
      12. 8.2.12 LM3410X WSON: Boot-Strap Circuit to Extend Battery Life
        1. 8.2.12.1 Design Requirements
  9. Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Examples
    3. 10.3 Thermal Considerations
      1. 10.3.1 Design
      2. 10.3.2 LM3410 and LM3410-Q1 Thermal Models
      3. 10.3.3 Calculating Efficiency and Junction Temperature
        1. 10.3.3.1 Quiescent Power Losses
        2. 10.3.3.2 RSET Power Losses
      4. 10.3.4 Example Efficiency Calculation
      5. 10.3.5 Calculating RθJA and RΨJC
  11. 11デバイスおよびドキュメントのサポート
    1. 11.1 デバイス・サポート
      1. 11.1.1 デバイスの関連用語
    2. 11.2 ドキュメントのサポート
      1. 11.2.1 関連資料
    3. 11.3 関連リンク
    4. 11.4 ドキュメントの更新通知を受け取る方法
    5. 11.5 コミュニティ・リソース
    6. 11.6 商標
    7. 11.7 静電気放電に関する注意事項
    8. 11.8 Glossary
  12. 12メカニカル、パッケージ、および注文情報

パッケージ・オプション

メカニカル・データ(パッケージ|ピン)
サーマルパッド・メカニカル・データ
発注情報

8 Application and Implementation

NOTE

Information in the following applications sections is not part of the TI component specification, and TI does not warrant its accuracy or completeness. TI’s customers are responsible for determining suitability of components for their purposes. Customers should validate and test their design implementation to confirm system functionality.

8.1 Application Information

8.1.1 Boost Converter

8.1.1.1 Setting the LED Current

LM3410 LM3410-Q1 30038517.gif Figure 12. Setting ILED

The LED current is set using the following equation:

Equation 1. LM3410 LM3410-Q1 30038518.gif

where

  • RSET is connected between the FB pin and GND.

8.1.1.2 LED-Drive Capability

When using the LM3410 or LM3410-Q1 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 (VFMAX).

Equation 2. (VFMAX × NLEDs) + 190 mV < 24 V

When inserting a value for maximum VFMAX the LED forward voltage variation over the operating temperature range must be considered.

8.1.1.3 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 decreases the input ripple current.

LM3410 LM3410-Q1 30038519.gif Figure 13. Inductor Current
Equation 3. LM3410 LM3410-Q1 30038520.gif

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

Equation 4. LM3410 LM3410-Q1 30038521.gif

Therefore:

Equation 5. LM3410 LM3410-Q1 30038522.gif

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 (RDCR) and switching losses must be included to calculate a more accurate duty cycle (see Calculating Efficiency and Junction Temperature for a detailed explanation). A more accurate formula for calculating the conversion ratio is:

Equation 6. LM3410 LM3410-Q1 30038523.gif

where

  • η equals the efficiency of the device application.

Or:

Equation 7. LM3410 LM3410-Q1 30038524.gif

Therefore:

Equation 8. LM3410 LM3410-Q1 30038525.gif

Inductor ripple in a LED driver circuit can be greater than what would normally be allowed in a voltage regulator Boost and Sepic design. A good design practice is to allow the inductor to produce 20% to 50% ripple of maximum load. The increased ripple is unlikely to be a problem when illuminating LEDs.

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

Equation 9. LM3410 LM3410-Q1 30038526.gif

where

  • 1 / TS = fSW

Ensure that the minimum current limit (2.1 A) is not exceeded, so the peak current in the inductor must be calculated. The peak current (Lpk I) in the inductor is calculated by Equation 10:

Equation 10. ILpk = IIN + ΔIL or ILpk = IOUT /D' + ΔiL

When selecting an inductor, make sure that it is capable of supporting the peak input current without saturating. Inductor saturation results 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 only needs to be specified for the required maximum input current. For example, if the designed maximum input current is 1.5 A and the peak current is 1.75 A, then the inductor must be specified with a saturation current limit of >1.75 A. There is no need to specify the saturation or peak current of the inductor at the 2.8-A typical switch current limit.

Because of the operating frequency of the LM3410 and LM3410-Q1, ferrite based inductors are preferred to minimize core losses. This presents little restriction because the variety of ferrite-based inductors is huge. Lastly, inductors with lower series resistance (DCR) provides better operating efficiency. For recommended inductor value examples, see Typical Applications.

8.1.1.4 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). TI recommens an input capacitance from 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 and LM3410-Q1, certain capacitors may have an ESL so large that the resulting impedance (2πfL) is higher than that required to provide stable operation. As a result, TI recommends surface mount capacitors. Multilayer ceramic capacitors (MLCC) are good choices for both input and output capacitors and have very low ESL. For MLCCs TI recommends use of X7R or X5R dielectrics. Consult the capacitor manufacturer's datasheet for rated capacitance variation over operating conditions.

8.1.1.5 Output Capacitor

The LM3410 and LM3410-Q1 operate 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 therefore determines the maximum voltage perturbation. The output ripple of the converter is a function of the capacitor’s reactance and its equivalent series resistance (ESR) (see Equation 11).

Equation 11. LM3410 LM3410-Q1 30038529.gif

When using MLCCs, the ESR is typically so low that the capacitive ripple may dominate. When this occurs, the output ripple is 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 or LM3410-Q1, there 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 couples through parasitic capacitances in the inductor to the output. A ceramic capacitor bypasses this noise while a tantalum does not. Because the output capacitor is one of the two external components that control the stability of the regulator control loop, most applications requires a minimum at 0.47 µF of output capacitance. Like the input capacitor, TI recommends X7R or X5R as multilayer ceramic capacitors. Again, verify actual capacitance at the desired operating voltage and temperature.

8.1.1.6 Diode

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

Equation 12. ID1 ≥ IOUT

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

8.1.1.7 Output Overvoltage Protection

A simple circuit consisting of an external Zener diode can be implemented to protect the output and the LM3410 or LM3410-Q1 device from an overvoltage fault condition. If an LED fails open, or is connected backwards, an output open circuit condition occurs. No current is conducted through the LEDs, and the feedback node equals zero volts. The LM3410 or LM3410-Q1 reacts to this fault by increasing the duty cycle, thinking the LED current has dropped. A simple circuit that protects the device is shown in Figure 14.

Zener diode D2 and resistor R3 is placed from VOUT in parallel with the string of LEDs. If the output voltage exceeds the 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 190 mV, the LM3410 and LM3410-Q1 limits their duty cycle. No damage occurs to the device, the LEDs, or the Zener diode. Once the fault is corrected, the application will work as intended.

LM3410 LM3410-Q1 30038530.gif Figure 14. Overvoltage Protection Circuit

8.1.2 SEPIC Converter

The LM3410 or LM3410-Q1 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 varies from 2.7 V to 4.5 V and the output voltage is somewhere in between. Most of the analysis of the LM3410 Boost Converter is applicable to the LM3410 SEPIC Converter.

LM3410 LM3410-Q1 30038552.gif Figure 15. HB or OLED SEPIC Converter Schematic

8.1.2.1 SEPIC Equations

SEPIC Conversion ratio without loss elements:

Equation 13. LM3410 LM3410-Q1 30038554.gif

Therefore:

Equation 14. LM3410 LM3410-Q1 30038555.gif

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 equals zero. Also, the charge into a capacitor equals the charge out of a capacitor in one cycle.

Therefore:

Equation 15. LM3410 LM3410-Q1 30038553.gif

Substituting IL1 into IL2

Equation 16. IL2 = ILED

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

LM3410 LM3410-Q1 30038556.gif Figure 16. Inductor Volt-Second Balance Waveform

Applying Charge balance on C1:

Equation 17. LM3410 LM3410-Q1 30038557.gif

Because 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

Equation 18. VC3 = VIN

Therefore:

Equation 19. LM3410 LM3410-Q1 30038558.gif

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

8.1.2.2 Steady State Analysis with Loss Elements

LM3410 LM3410-Q1 30038559.gif Figure 17. SEPIC Simplified Schematic

8.1.2.2.1 Details

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

Equation 20. IL2 = (ILED)

and

Equation 21. IL1 = (ILED) × (D/D')
Equation 22. LM3410 LM3410-Q1 30038561.gif
Equation 23. LM3410 LM3410-Q1 30038540.gif

Therefore:

Equation 24. LM3410 LM3410-Q1 30038562.gif

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.

Equation 25. LM3410 LM3410-Q1 30038563.gif
Equation 26. LM3410 LM3410-Q1 30038564.gif

Table 1. Efficiencies for Typical SEPIC Applications

EXAMPLE 1 EXAMPLE 2 EXAMPLE 3
VIN 2.7 V VIN 3.3 V VIN 5 V
VOUT 3.1 V VOUT 3.1 V VOUT 3.1 V
IIN 770 mA IIN 600 mA IIN 375 mA
ILED 500 mA ILED 500 mA ILED 500 mA
η 75% η 80% η 83%

8.2 Typical Applications

8.2.1 Low Input Voltage, 1.6-MHz, 3 to 5 White LED Output at 50-mA Boost Converter

LM3410 LM3410-Q1 30038501.gif Figure 18. Boost Schematic

8.2.1.1 Design Requirements

For this design example, use the parameters listed in Table 2 as the input parameters.

Table 2. Design Parameters

PARAMETER EXAMPLE VALUE
VIN 2.7 V to 5.5 V
ILED 50 mA
VOUT 14.6 V (four 3.6-V LEDs in series plus 190 mV)
RD 8 Ω (dynamic resistance of 4 LEDs in series)
ΔILp–p 100 mA (maximum)
ΔVOUTp–p 250 mV (maximum)

8.2.1.2 Detailed Design Procedure

This design procedure uses the worst-case minimum input voltage and a nominal 4 LED series load for calculations.

8.2.1.2.1 Set the LED Current (R1)

Rearranging the LED current equation the current sense resistor R1 can be found using Equation 27.

Equation 27. LM3410 LM3410-Q1 appex_R1_eq_snvs541.gif

3.8 Ω is not a standard value so a standard value of R1 = 3.83 Ω is chosen.

8.2.1.2.2 Calculate Maximum Duty Cycle (DMAX)

The maximum duty cycle is required for calculating the inductor value and the minimum output capacitance. Assuming an approximate conversion efficiency (η) of 90% DMAX is calculated using Equation 28.

Equation 28. LM3410 LM3410-Q1 appex_Dmax_eq_snvs541.gif

8.2.1.2.3 Calculate the Inductor Value (L1)

Using the maximum duty cycle, the minimum input voltage, and the maximum inductor ripple current (ΔiLp–p) the minimum inductor value to achieve the maximum ripple current is calculated using Equation 29.

Equation 29. LM3410 LM3410-Q1 appex_L_eq_snvs541.gif

To ensure the maximum inductor ripple current requirement is met with a 20% inductor tolerance an inductor value of L1 = 10 µH is selected.

8.2.1.2.4 Calculate the Output Capacitor (C2)

To maintain a maximum of 250-mV output voltage ripple the dynamic resistance of the LED stack (RD) must be used. Assuming a ceramic capacitor is used so the ESR can be neglected this minimum amount of capacitance can be found using Equation 30.

Equation 30. LM3410 LM3410-Q1 appex_cout_eq_snvs541.gif

1.9 µF is not a standard value so a value of C2 = 2.2 µF is selected.

8.2.1.2.5 Input Capacitor (C1) and Schottky Diode (D1)

TI recommends an input capacitor from 2.2 µF to 22 µF. This is a relatively low power design optimized for a small footprint. For a good balance of input filtering and small size a 6.3-V capacitor with a value of C1 = 10 µF is selected. The output voltage with a 5 LED load is over 18 V and the reverse voltage of the schottky diode must be greater than this voltage. To give some headroom to avoid reverse breakdown and to maintain small size and reliability the diode selected is D1 = 30 V, 500 mA.

8.2.1.3 Application Curves

LM3410 LM3410-Q1 30038502.gif Figure 19. Efficiency versus Input Voltage
LM3410 LM3410-Q1 30038509.png Figure 20. PWM Dimming

8.2.2 LM3410X SOT-23: 5 × 1206 Series LED String Application

LM3410 LM3410-Q1 30038581.gif Figure 21. LM3410X (1.6 MHz) 5 × 3.3-V LED String Application Diagram

8.2.2.1 Design Requirements

For this design example, use the parameters listed in Table 3 as the input parameters.

Table 3. Design Parameters

PARAMETER EXAMPLE VALUE
VIN 2.7 V to 5.5 V
ILED ≊50 mA
VOUT ≊16.5 V (five 3.3-V LEDs in series)

Table 4. Part Values

PART VALUE
U1 2.8-A ISW LED Driver
C1, Input capacitor 10 µF, 6.3 V, X5R
C2, Output capacitor 2.2 µF, 25 V, X5R
D1, Catch diode 0.4-Vf Schottky 500 mA, 30 VR
L1 10 µH, 1.2 A
R1 4.02 Ω, 1%
R2 100 kΩ, 1%
LEDs SMD-1206, 50 mA, Vf ≊ 3.6 V

8.2.3 LM3410Y SOT-23: 5 × 1206 Series LED String Application

LM3410 LM3410-Q1 30038581.gif Figure 22. LM3410Y (525 kHz) 5 × 3.3-V LED String Application Diagram

8.2.3.1 Design Requirements

For this design example, use the parameters listed in Table 5 as the input parameters.

Table 5. Design Parameters

PARAMETER EXAMPLE VALUE
VIN 2.7 V to 5.5 V
ILED ≊50 mA
VOUT ≊16.5 V (five 3.3-V LEDs in series)

Table 6. Part Values

PART VALUE
U1 2.8-A ISW LED Driver
C1, Input capacitor 10 µF, 6.3 V, X5R
C2, Output capacitor 2.2 µF, 25 V, X5R
D1, Catch diode 0.4-Vf Schottky 500 mA, 30 VR
L1 15 µH, 1.2 A
R1 4.02 Ω, 1%
R2 100 kΩ, 1%
LEDs SMD-1206, 50 mA, Vf ≊ 3.6 V

8.2.4 LM3410X WSON: 7 × 5 LED Strings Backlighting Application

LM3410 LM3410-Q1 300385a2.gif Figure 23. LM3410X (1.6 MHz) 7 × 5 × 3.3-V LEDs Backlighting Application Diagram

8.2.4.1 Design Requirements

For this design example, use the parameters listed in Table 7 as the input parameters.

Table 7. Design Parameters

PARAMETER EXAMPLE VALUE
VIN 2.7 V to 5.5 V
ILED ≊25 mA
VOUT ≊16.7 V (seven strings of five 3.3-V LEDs in series)

Table 8. Part Values

PART VALUE
U1 2.8-A ISW LED Driver
C1, Input capacitor 10 µF, 6.3 V, X5R
C2, Output capacitor 4.7 µF, 25 V, X5R
D1, Catch Diode 0.4-Vf Schottky 500 mA, 30 VR
L1 8.2 µH, 2 A
R1 1.15 Ω, 1%
R2 100 kΩ, 1%
LEDs SMD-1206, 50 mA, Vf ≊ 3.6 V

8.2.5 LM3410X WSON: 3 × HB LED String Application

LM3410 LM3410-Q1 30038567.gif Figure 24. LM3410X (1.6 MHz) 3 × 3.4-V LED String Application Diagram

8.2.5.1 Design Requirements

For this design example, use the parameters listed in Table 9 as the input parameters.

Table 9. Design Parameters

PARAMETER EXAMPLE VALUE
VIN 2.7 V to 5.5 V
ILED ≊340 mA
VOUT ≊11 V (three 3.4-V LEDs in series)

Table 10. Part Values

PART VALUE
U1 2.8-A ISW LED Driver
C1, Input capacitor 10 µF, 6.3 V, X5R
C2, Output capacitor 2.2 µF, 25 V, X5R
D1, Catch diode 0.4-Vf Schottky 500 mA, 30 VR
L1 10 µH, 1.2 A
R1 1 Ω, 1%
R2 100 kΩ, 1%
R3 1.5 Ω, 1%
HB – LEDs 340 mA, Vf ≊ 3.6 V

8.2.6 LM3410Y SOT-23: 5 × 1206 Series LED String Application With OVP

LM3410 LM3410-Q1 30038568.gif Figure 25. LM3410Y (525 kHz) 5 × 3.3-V LED String Application With OVP Diagram

8.2.6.1 Design Requirements

For this design example, use the parameters listed in Table 11 as the input parameters.

Table 11. Design Parameters

PARAMETER EXAMPLE VALUE
VIN 2.7 V to 5.5 V
ILED ≊50 mA
VOUT ≊16.5 V (five 3.3-V LEDs in series)

Table 12. Part Values

PART VALUE
U1 2.8-A ISW LED Driver
C1, Input capacitor 10 µF, 6.3 V, X5R
C2, Output capacitor 2.2 µF, 25 V, X5R
D1, Catch diode 0.4-Vf Schottky 500 mA, 30 VR
D2 18 V Zener diode
L1 15 µH, 0.7 A
R1 4.02 Ω, 1%
R2 100 kΩ, 1%
R3 100 Ω, 1%
LEDs SMD-1206, 50 mA, Vf ≊ 3.6 V

8.2.7 LM3410X SEPIC WSON: HB or OLED Illumination Application

LM3410 LM3410-Q1 30038552.gif Figure 26. LM3410X (1.6 MHz) HB or OLED Illumination Application Diagram

8.2.7.1 Design Requirements

For this design example, use the parameters listed in Table 13 as the input parameters.

Table 13. Design Parameters

PARAMETER EXAMPLE VALUE
VIN 2.7 V to 5.5 V
ILED ≊300 mA
VOUT ≊3.8 V

Table 14. Part Values

PART VALUE
U1 2.8-A ISW LED Driver
C1, Input capacitor 10 µF, 6.3 V, X5R
C2, Output capacitor 10 µF, 6.3 V, X5R
C3 2.2 µF, 25 V, X5R
D1, Catch diode 0.4-Vf Schottky 1 A, 20 VR
L1 and L2 4.7 µH, 3 A
R1 665 mΩ, 1%
R2 100 kΩ, 1%
HB – LEDs 350 mA, Vf ≊ 3.6 V

8.2.8 LM3410X WSON: Boost Flash Application

LM3410 LM3410-Q1 30038570.gif Figure 27. LM3410X (1.6 MHz) Boost Flash Application Diagram

8.2.8.1 Design Requirements

For this design example, use the parameters listed in Table 15 as the input parameters.

Table 15. Design Parameters

PARAMETER EXAMPLE VALUE
VIN 2.7 V to 5.5 V
ILED ≊1 A (pulse)
VOUT ≊8 V

Table 16. Part Values

PART VALUE
U1 2.8-A ISW LED Driver
C1, Input capacitor 10 µF, 6.3 V, X5R
C2, Output capacitor 10 µF, 16 V, X5R
D1, Catch diode 0.4-Vf Schottky 500 mA, 30 VR
L1 4.7 µH, 3 A
R1 200 mΩ, 1%
LEDs 500 mA, Vf ≊ 3.6 V, IPULSE = 1 A

8.2.9 LM3410X SOT-23: 5 × 1206 Series LED String Application With VIN > 5.5 V

LM3410 LM3410-Q1 30038571.gif Figure 28. LM3410X (1.6 MHz) 5 × 1206 Series LED String Application With VIN > 5.5 V Diagram

8.2.9.1 Design Requirements

For this design example, use the parameters listed in Table 17 as the input parameters.

Table 17. Design Parameters

PARAMETER EXAMPLE VALUE
VPWR 9 V to 14 V
ILED ≊50 mA
VOUT ≊16.5 V (five 3.3-V LEDs in series)

Table 18. Part Values

PART VALUE
U1 2.8-A ISW LED Driver
C1, Input VPWRcapacitor 10 µF, 6.3 V, X5R
C2, Output capacitor 2.2 µF, 25 V, X5R
C3, Input VIN capacitor 0.1 µF, 6.3 V, X5R
D1, Catch diode 0.43-Vf Schottky 500 mA, 30 VR
D2 3.3 V Zener, SOT-23
L1 10 µH, 1.2 A
R1 4.02 Ω, 1%
R2 100 kΩ, 1%
R3 576 Ω, 1%
LEDs SMD-1206, 50 mA, Vf ≊ 3.6 V

8.2.10 LM3410X WSON: Camera Flash or Strobe Circuit Application

LM3410 LM3410-Q1 30038572.gif Figure 29. LM3410X (1.6 MHz) Camera Flash or Strobe Circuit Application Diagram

8.2.10.1 Design Requirements

For this design example, use the parameters listed in Table 19 as the input parameters.

Table 19. Design Parameters

PARAMETER EXAMPLE VALUE
VIN 2.7 V to 5.5 V
ILED ≊1.5 A (flash)
VOUT ≊7.5 V

Table 20. Part Values

PART VALUE
U1 2.8-A ISW LED Driver
C1, Input capacitor 10 µF, 6.3 V, X5R
C2, Output capacitor 220 µF, 10 V, tantalum
C3 capacitor 10 µF, 16 V, X5R
D1, Catch diode 0.43-Vf Schottky 1 A, 20 VR
L1 3.3 µH, 2.7 A
R1 1 Ω, 1%
R2 37.4 kΩ, 1%
R3 100 kΩ, 1%
R4 0.15 Ω, 1%
Q1 and Q2 30 V, ID = 3.9 A
LEDs SMD-1206, 50 mA, Vf ≊ 3.6 V, IPULSE = 1.5 A

8.2.11 LM3410X SOT-23: 5 × 1206 Series LED String Application With VIN and VPWR Rail > 5.5 V

LM3410 LM3410-Q1 30038573.gif Figure 30. LM3410X (1.6 MHz) 5 × 1206 Series LED String Application With VIN and VPWR Rail > 5.5 V Diagram

8.2.11.1 Design Requirements

For this design example, use the parameters listed in Table 21 as the input parameters.

Table 21. Design Parameters

PARAMETER EXAMPLE VALUE
VPWR 9 V to 14 V
VIN 2.7 V to 5.5 V
ILED ≊50 mA
VOUT ≊16.5 V (five 3.3-V LEDs in series)

Table 22. Part Values

PART VALUE
U1 2.8-A ISW LED Driver
C1, Input VPWRcapacitor 10 µF, 6.3 V, X5R
C2, Output capacitor 2.2 µF, 25 V, X5R
C3, Input VIN capacitor 0.1 µF, 6.3 V, X5R
D1, Catch diode 0.43-Vf Schottky 500 mA, 30 VR
L1 10 µH, 1.2 A
R1 4.02 Ω, 1%
R2 100 kΩ, 1%
LEDs SMD-1206, 50 mA, Vf ≊ 3.6 V

8.2.12 LM3410X WSON: Boot-Strap Circuit to Extend Battery Life

LM3410 LM3410-Q1 30038574.gif Figure 31. LM3410X (1.6 MHz) Boot-Strap Circuit to Extend Battery Life

8.2.12.1 Design Requirements

For this design example, use the parameters listed in Table 3 as the input parameters.

Table 23. Design Parameters

PARAMETER EXAMPLE VALUE
VIN 1.9 V to 5.5 V
>2.3 V (typical) for start-up
ILED ≊300 mA

Table 24. Part Values

PART VALUE
U1 2.8-A ISW LED Driver
C1, Input VPWR capacitor 10 µF, 6.3 V, X5R
C2, Output capacitor 10 µF, 6.3 V, X5R
C3, Input VIN capacitor 0.1 µF, 6.3 V, X5R
D1, Catch diode 0.43-Vf Schottky 1 A, 20 VR
D2 and D3 Dual small signal Schottky
L1 and L2 3.3 µH, 3 A
R1 665 mΩ, 1%
R3 100 kΩ, 1%
HB – LEDs 350 mA, Vf ≊ 3.4 V