LM3410XMY_技术文档

LM3410, LM3410Q

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SNVS541G –OCTOBER 2007–REVISED MAY 2013

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

Compensation

Check for Samples: LM3410, LM3410Q

1

FEATURES

DESCRIPTION

The LM3410 constant current LED driver is a

monolithic, high frequency, PWM DC/DC converter in

5-pin

23

•

Space Saving SOT-23 and WSON Packages

Input Voltage Range of 2.7V to 5.5V

Output Voltage Range of 3V to 24V

2.8A Typical Switch Current

•

SOT-23, 6-pin WSON, and 8-pin MSOP-PowerPad™

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.

High Switching Frequency

–

525 KHz (LM3410Y)

1.6 MHz (LM3410X)

•

170 mΩ NMOS Switch

190 mV Internal Voltage Reference

Internal Soft-Start

Current-Mode, PWM Operation

Thermal Shutdown

LM3410Q is AEC-Q100 Grade 1 Qualified and

is Manufactured on an Automotive Grade Flow

APPLICATIONS

•

LED Backlight Current Source

LiIon Backlight OLED and HB LED Driver

Handheld Devices

LED Flash Driver

Automotive

Typical Boost Application Circuit

L

D

1

V

IN

DIMM

4

3

FB

2

LEDs

DIM

C

2

GND

1

5

SW

VIN

C

1

R

1

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.

2

3

PowerPad is a trademark of Texas Instruments.

All other 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.

LM3410, LM3410Q

SNVS541G –OCTOBER 2007–REVISED MAY 2013

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Connection Diagram

SW

1

5

4

VIN

DIM

PGND

VIN

SW

NC

PGND

VIN

1

2

3

4

8

7

6

5

NC

1

2

6

5

SW

GND

2

3

AGND

FB

DIM

FB

3

4

Figure 1. 5-Pin SOT-23 (Top

View)

Figure 2. 6-Pin WSON (Top View) Figure 3. 8-Pin MSOP-PowerPad

(Top View)

See NGG0006A Package

See DBV Package

See GDN0008A Package

Table 1. Pin Descriptions - 5-Pin SOT-23

1

Name

SW

Function

Output switch. Connect to the inductor, output diode.

2

GND

FB

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

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

3

Dimming and 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.

4

5

DIM

VIN

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

Table 2. Pin Descriptions - 6-Pin WSON

1

Name

PGND

VIN

Function

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

Supply voltage for power stage, and input supply voltage.

2

Dimming and 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.

3

DIM

4

5

6

FB

AGND

SW

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

Signal ground pin. Place the bottom resistor of the feedback network as close as possible to this pin and pin 4.

Output switch. Connect to the inductor, output diode.

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

plane.

DAP

GND

2

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Table 3. Pin Descriptions - 8-Pin MSOP-PowerPad

1

Name

-

Function

No Connect

2

PGND

VIN

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

Supply voltage for power stage, and input supply voltage.

3

Dimming and 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.

4

DIM

5

6

7

8

FB

AGND

SW

-

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

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

Output switch. Connect to the inductor, output diode.

No Connect

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

plane.

DAP

GND

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.

(1)(2)

Absolute Maximum Ratings

V_IN

-0.5V to 7V

-0.5V to 26.5V

-0.5V to 3.0V

-0.5V to 7.0V

2kV

SW Voltage

FB Voltage

DIM Voltage

ESD Susceptibility

(3)

Human Body Model

(4)

Junction Temperature

Storage Temp. Range

Soldering Information

150°C

-65°C to 150°C

220°C

Infrared/Convection Reflow (15sec)

(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 ensure specific performance limits. For ensured specifications and conditions,

see the Electrical Characteristics.

(2) If Military/Aerospace specified devices are required, please contact the TI Sales Office/ Distributors for availability and specifications.

(3) 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.

(4) Thermal shutdown will occur if the junction temperature exceeds the maximum junction temperature of the device.

(1)

Operating Ratings

V_IN

2.7V to 5.5V

0V to V_IN

(2)

V_DIM

V_SW

3V to 24V

Junction Temperature Range

-40°C to 125°C

Power Dissipation

(Internal) SOT-23

400 mW

(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 ensure specific performance limits. For ensured specifications and conditions,

see the Electrical Characteristics.

(2) Do not allow this pin to float or be greater than V_IN+0.3V.

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Electrical Characteristics

Limits in standard type are for T_J= 25°C only; limits in boldface type apply over the junction temperature (T_J) 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 at T_J= 25°C, and are provided for reference purposes only. V_IN= 5V, unless otherwise

indicated under the Conditions column.

Symbol

V_FB

Parameter

Feedback Voltage

Conditions

Min

Typ

190

0.06

0.1

1600

525

92

Max

Units

mV

178

202

ΔV_FB/V_IN

I_FB

Feedback Voltage Line Regulation

Feedback Input Bias Current

V_IN= 2.7V to 5.5V

-

%/V

µA

-

1200

360

88

90

-

1

LM3410X

2000

F_SW

Switching Frequency

Maximum Duty Cycle

Minimum Duty Cycle

Switch On Resistance

kHz

%

LM3410Y

680

LM3410X

-

D_MAX

LM3410Y

95

-

LM3410X

5

-

D_MIN

%

LM3410Y

-

2

-

SOT-23 and MSOP-PowerPad

WSON

-

170

190

2.80

20

330

R_DS(ON)

mΩ

350

I_CL

Switch Current Limit

Start Up Time

2.1

-

A

SU

-

µs

LM3410X V_FB= 0.25

LM3410Y V_FB= 0.25

All Options V_DIM= 0V

V_INRising

-

7.0

3.4

80

11

Quiescent Current (switching)

Quiescent Current (shutdown)

Undervoltage Lockout

mA

nA

V

I_Q

-

7

-

2.3

1.9

-

2.65

UVLO

V_INFalling

1.7

-

Shutdown Threshold Voltage

Enable Threshold Voltage

Switch Leakage

-

0.4

V_{DIM_H}

V

1.8

-

I_SW

V_SW= 24V

-

1.0

100

80

µA

nA

I_DIM

Dimming Pin Current

Sink/Source

WSON and MSOP-PowerPad Packages

SOT-23 Package

Junction to Ambient

θ_JA

°C/W

(1)

0 LFPM Air Flow

118

18

WSON and MSOP-PowerPad Packages

SOT-23 Package

(1)

θ_JC

Junction to Case

°C/W

°C

60

(2)

T_SD

Thermal Shutdown Temperature

165

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

(2) Thermal shutdown will occur if the junction temperature exceeds the maximum junction temperature of the device.

4

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Typical Performance Characteristics

All curves taken at V_IN= 5.0V with configuration in typical application circuit shown in Application Information section of this

datasheet. T_J= 25C, unless otherwise specified.

LM3410X Efficiency vs V_IN(R_SET= 4Ω)

LM3410X Start-Up Signature

Figure 4.

Figure 5.

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

DIM Freq and Duty Cycle vs Avg I-LED

Figure 6.

Figure 7.

Current Limit vs Temperature

R_DSONvs Temperature

Figure 8.

Figure 9.

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Typical Performance Characteristics (continued)

All curves taken at V_IN= 5.0V with configuration in typical application circuit shown in Application Information section of this

datasheet. T_J= 25C, unless otherwise specified.

Oscillator Frequency vs Temperature - "X"

Oscillator Frequency vs Temperature - "Y"

Figure 10.

Figure 11.

V_FBvs Temperature

Figure 12.

6

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Simplified Internal Block Diagram

DIM

VIN

Thermal_SHDN

-

Control Logic

+

-

UVLO = 2.3V

Ramp_Artificial

Oscillator

cv

1.6 MHz

R

S

R

+

SW

+

NMOS

+

-

Q

-

V_FB

+

Internal

Compensation

V_REF= 190 mV

I_LIMIT

I_SENSE

+

-

GND

Figure 13. Simplified Block Diagram

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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 13) the simplified schematic

(Figure 14), and its associated waveforms (Figure 15). The LM3410 supplies a regulated LED current by

switching the internal NMOS control 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 control switch. During this on-time, the SW pin voltage (V_SW

)

decreases to approximately GND, and the inductor current (I_L) increases with a linear slope. I_Lis 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_REF. When the PWM comparator output goes high, the

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

(V_D) of the diode. The regulator loop adjusts the duty cycle (D) to maintain a regulated LED current.

V

O

I

L1

D1

L

I

Q1

C

+

V

IN

Control

V

SW

-

C1

I

LED

Figure 14. Simplified Boost Topology Schematic

8

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V_OUT+ V_D

V

( )

sw t

t

V

IN

V

( )

L t

t

V

-V

OUT D

IN

I

i

( )

L t

L

t

I

( )

DIODE t

t

i

- i

-

OUT

(

L

)

I

( )

t

Capacitor

t

- i

OUT

Dv

V

( )

t

OUT

DT

T

S

Figure 15. 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.

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Design Guide

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SETTING THE LED CURRENT

I

LED

V

FB

R_SET

Figure 16. Setting I_LED

The LED current is set using the following equation:

V_FB

= I_LED

R_SET

where

•

R_SETis connected between the FB pin and GND.

(1)

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 and 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 and 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_MAXx N_LEDs) + 190 mV < 24V

(2)

When inserting a value for maximum VF_MAXthe LED forward voltage variation over the operating temperature

range should be considered.

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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Di

I

( )

L t

L

i

L

V

IN

L

V

-V

OUT

IN

L

DT

S

T

S

t

Figure 17. Inductor Current

V

≈

’

2Di_L

DT_S

IN

= ∆

÷

∆

L

«

◊

V

≈

’

IN

x DT

∆

÷

Di =

L

S

2L

«

◊

(3)

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

voltage (V_IN).

V_OUT

V_IN

1

≈

’

=

∆

÷

Å

1 - D

D

«

◊

(4)

Therefore:

V_OUT- V_IN

V_OUT

D =

(5)

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_DCR) 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:

h

V_OUT

V_IN

=

D‘

Where

•

η equals the efficiency of the LM3410 application.

(6)

(7)

(8)

Or:

V_OUTx I_LED

h =

V_INx I_IN

Therefore:

V_OUT- hV_IN

D =

V_OUT

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 shouldn’t be a problem when illuminating LEDs.

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

V

2Di_L

≈

’

IN

x DT

∆

÷

L =

S

«

◊

(9)

Where

1/T_S= f_SW

(10)

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:

I_Lpk= I_IN+ ΔI_Lor I_Lpk= I_OUT/D' + Δi_L

(11)

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 V_INdoes 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.

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):

V_OUTx D

≈

∆

«

’

÷

◊

DV_OUT= Di_Lx R_ESR

+

2 x f_SWx R_OUTx C_OUT

(12)

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.

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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:

I_D1≥ I_OUT

(13)

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 18.

Zener diode D2 and resistor R3 is placed from V_OUTin 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 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.

D

1

LEDs

V

SW

O

V

P

D

2

C

2

R

3

V

FB

R

1

Figure 18. 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_OUTcapacitor 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_SETfeedback resistor should be placed as close as possible to the IC, with the AGND of R_SET(R1) placed as

close as possible to the AGND (pin 5 for the WSON) of the IC. Radiated 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

TI Lit Number SNVA054 for further considerations and the LM3410 demo board as an example of a four-layer

layout.

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

LED_s

PCB

R₁

P_GND

DIM

FB

4

3

2

1

A_GND

5

C₂

V_IN

V_SW

6

V_O

P_GND

D₁

C₁

SW

L₁

Figure 19. Boost PCB Layout Guidelines

This is very similar to our LM3410 demonstration boards that are obtainable via the Texas Instruments 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 performance has been improved by

adding thermal vias and a top layer “Dog-Bone”.

For certain high power applications, the PCB land may be modified to a "dog bone" shape (see Figure 20).

Increasing the size of ground plane and adding thermal vias can reduce the R_θJAfor the application.

COPPER

1

2

6

5

SW

PGND

VIN

AGND

3

4

FB

DIM

COPPER

Figure 20. 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.

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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 SOT-23, 8-pin MSOP-PowerPad and 6-pin WSON). The options are electrically the

same, but difference between the packages is size and thermal performance. The WSON and MSOP-PowerPad

have thermal Die Attach Pads (DAP) attached to the bottom of the packages, and are therefore capable of

dissipating more heat than the SOT-23 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.

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

R

C

R

_θJA: Thermal impedance from silicon junction to ambient air temperature.

_θJC: Thermal impedance from silicon junction to device case temperature.

_θJC: Thermal Delay from silicon junction to device case temperature.

_θCA: Thermal Delay from device case to ambient air temperature.

_θJAand R_θJC: These two symbols represent thermal impedances, and most data sheets contain associated

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

R_θJAis the sum of smaller thermal impedances (see simplified thermal model Figure 21 and Figure 22).

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, V_IN, V_OUT, load current etc). This

does shed light on the package performance, but it would be a mistake to use 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.

L

1

I

D

1

L(t)

V

OUT(t)

V

Q

1

IN

C

1

Figure 21. Thermal Schematic

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R_qCASE-AMB

T_CASE

C_qCASE-AMB

R_qJ-CASE

C_qJ-CASE

INTERNAL

P_DISS

SMALL

LARGE

P_DISS-TOP

T_AMBIENT

P_DISS-PCB

T_JUNCTION

C_qJ-PCB

R_qJ-PCB

DEVICE

EXTERNAL

P_DISS

R_qPCB-AMB

T_PCB

C_qPCB-AMB

PCB

Figure 22. Associated Thermal Model

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Calculating Efficiency and Junction Temperature

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.

T_J- T_A

R_qJA

=

P_Dissipation

(14)

A common error when calculating R_θJAis to assume that the package is the only variable to consider.

R_θJA[variables]:

•

Input Voltage, Output Voltage, Output Current, R_DS(ON)

Ambient temperature and air flow

•

Internal and 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_θJC. R_θJCrepresents the thermal impedance of all six sides of a package,

not just the top side. This document will refer to a thermal impedance called R_ΨJC. R_ΨJCrepresents 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.

P_OUT

h =

P_IN

or

P_OUT

h =

P_OUT+ P_LOSS

(15)

Power loss (P_LOSS) is the sum of two types of losses in the converter, switching and conduction. Conduction

losses usually 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+ P_SW+ P_Q

Where

•

P_Q= quiescent operating power loss

(16)

Conversion ratio of the Boost Converter with conduction loss elements inserted:

≈

∆

’

÷

Å

≈

’

÷

◊

V_OUT

D x V_D

1

∆

÷

1

Å

D

∆

1-

=

∆

V

R_DCR+ D x R

V

(

)

IN

DSON

IN

«

∆

«

÷

◊

1+

Å²

R _OUT

D

Where

•

R_DCR= Inductor series resistance

(17)

(18)

V_OUT

R_OUT

=

I_LED

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

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V_OUT

V_IN

1

=

D‘

(19)

(20)

And we know:

h

V_OUT

=

V_IN

D‘

Therefore:

Å

≈

∆

D x V_D

’

÷

1-

V

V_OUT

∆

÷

IN

Å

h =

=

D

V

R_DCR+ D x R

(

)

IN

DSON

∆

«

÷

◊

1+

Å²

R_OUT

D

(21)

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:

Å

≈

∆

D x V_D

’

÷

1-

V

∆

÷

IN

h ö

R_DCR+ D x R

(

)

DSON

∆

«

÷

◊

1+

Å²

R_OUT

D

(22)

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

zero will simplify the equation.

V_Dis 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:

P_DIODE= V_Dx I_LED

(23)

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:

2

P_IND= I_INR_DCR

(24)

Or

2

≈

∆

«

’

÷

◊

I_OR_DCR

P

=

IND

'

D

(25)

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

P_COND-NFET= I²_SW-rmsx R_DSONx D

(26)

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Di

I_IN

I_SW(t)

t

Figure 23. LM3410 Switch Current

2

Di

I_IND

1

3

D x

Isw-rms = I_IND

1 +

D

I

ö _IND

(27)

(28)

(small ripple approximation)

P_COND-NFET= I_IN²x R_DSONx D

Or

2

≈

’

I_LED

P

x R_DSONx D

=

∆

«

÷

COND- NFET

'

D

◊

(29)

The value for R_DSONshould be equal to the resistance at the junction temperature you wish to analyze. As an

example, at 125°C and R_DSON= 250 mΩ (See typical graphs for value).

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:

P_SWR= 1/2(V_OUTx I_INx f_SWx t_RISE

)

(30)

(31)

(32)

P_SWF= 1/2(V_OUTx I_INx f_SWx t_FALL

)

P_SW= P_SWR+ P_SWF

Table 4. Typical Switch-Node Rise and Fall Times

V_IN

3V

5V

3V

5V

V_OUT

5V

t_RISE

6nS

t_FALL

4nS

5nS

7nS

8nS

12V

18V

6nS

8nS

10nS

Quiescent Power Losses

I_Qis the quiescent operating current, and is typically around 1.5 mA.

P_Q= I_Qx V_IN

(33)

(34)

(35)

R_SETPower Loss

2

V_FB

P_RSET

=

R_SET

Example Efficiency Calculation:

Operating Conditions:

5 x 3.3V LEDs + 190mV_REF≊ 16.7V

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Table 5. Operating Conditions

V_IN

V_OUT

I_LED

V_D

3.3V

16.7V

50mA

0.45V

1.60MHz

3mA

f_SW

I_Q

t_RISE

t_FALL

R_DSON

L_DCR

D

10nS

225mΩ

75mΩ

0.82

I_IN

0.31A

ΣP_COND+ P_SW+ P_DIODE+ P_IND+ P_Q= P_LOSS

(36)

Quiescent Power Loss:

P_Q= I_Qx V_IN= 10 mW

(37)

Switching Power Loss:

P_SWR= 1/2(V_OUTx I_INx f_SWx t_RISE) ≊ 40 mW

P_SWF= 1/2(V_OUTx I_INx f_SWx t_FALL) ≊ 40 mW

P_SW= P_SWR+ P_SWF= 80 mW

(38)

(39)

(40)

Internal NFET Power Loss:

R_DSON= 225 mΩ

(41)

(42)

(43)

P_CONDUCTION= I_IN²x D x R_DSON= 17 mW

I_IN= 310 mA

Diode Loss:

V_D= 0.45V

(44)

(45)

P_DIODE= V_Dx I_LED= 23 mW

Inductor Power Loss:

R_DCR= 75 mΩ

(46)

(47)

P_IND= I_IN²x R_DCR= 7 mW

Total Power Losses are:

Table 6. Power Loss Tabulation

V_IN

V_OUT

I_LED

V_D

3.3V

16.7V

50mA

0.45V

1.6MHz

10nS

P_OUT

825W

P_DIODE

23mW

f_SW

I_Q

t_RISE

I_Q

P_SWR

P_SWF

P_Q

40mW

10mW

17mW

7mW

10nS

3mA

R_DSON

L_DCR

D

225mΩ

75mΩ

0.82

P_COND

P_IND

η

85%

P_LOSS

137mW

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P_INTERNAL= P_COND+ P_SW= 107 mW

(48)

Calculating R_θJAand R_ΨJC

T - T_A

T - T_Case

J

:

R_YJC=

R_qJA

=

P_Dissipation

(49)

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 R_θJAand/or R_ΨJC. 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 R_θJAor the R_ΨJCof 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 R_ΨJCis lower than for R_θJA. However, you will need

to attach a small thermocouple onto the top case of the LM3410 to obtain the R_ΨJCvalue.

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 (SOT-23 Package):

P_INTERNAL= 107 mW

(50)

(51)

(52)

T_A@ Shutdown = 155°C

T_C@ Shutdown = 159°C

T - T_A

T - T_Case-Top

J

:

R_YJC=

R_qJA

=

P_Dissipation

(53)

(54)

(55)

R

_θJASOT-23 = 93°C/W

_ΨJCSOT-23 = 56°C/W

R

Typical WSON and MSOP-PowerPad typical applications will produce R_θJAnumbers in the range of 50°C/W to

65°C/W, and R_ΨJCwill 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 24 shows the nonlinear relationship of

internal power dissipation vs . R_θJA

.

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Figure 24. R_θJAvs Internal Dissipation

For 5-pin SOT-23 package typical applications, R_θJAnumbers will range from 80°C/W to 110°C/W, and R_ΨJCwill

vary between 50°C/W and 65°C/W. These values are for PCB’s with two and 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 WSON or the 8-pin MSOP-PowerPad

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 and 4.5V and the output voltage is somewhere in between. Most of the

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

SEPIC Design Guide:

SEPIC Conversion ratio without loss elements:

V_OUT

V_IN

D

=

D‘

(56)

(57)

Therefore:

V_OUT

D =

V_OUT+ V_IN

Small ripple approximation:

In a well-designed SEPIC converter, the output voltage, and input voltage ripple, the inductor ripple I_L1and I_L2is

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:

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'

≈ ’

D

I_{L2 =}

x I_L1

∆

÷

D

« ◊

and

D

₌≈ ’

I_L1

∆

'÷ ^x

I_LED

« ^D◊

(58)

(59)

Substituting I_L1into I_L2

I_L2= I_LED

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

V

( )

AREA

1

L t

t

(s)

AREA

2

DT

T

S

Figure 25. Inductor Volt-Sec Balance Waveform

Applying Charge balance on C1:

'

(

)

V_OUT

D

V_C3

=

D

(60)

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

V_C3= V_IN

(61)

Therefore:

'

(

)

V_OUT

D

V_IN=

D

(62)

This verifies the original conversion ratio equation.

It is important to remember that the internal switch current is equal to I_L1and I_L2during the D interval. Design the

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

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V

IN

V

O

L

1

C

3

D

1

LM3410

C

1

C

2

L

2

HB/OLED

1

2

3

6

5

4

R

2

R

1

Figure 26. HB/OLED SEPIC CONVERTER Schematic

Steady State Analysis with Loss Elements

v

( )

C1 t

+

( )

L1 t

-

+

i

L1(t)

C1(t)

D1(t)

R

v

L1

( )

D1 t

i

C2(t)

L2(t)

sw

-

V

IN

v

( )

L2 t

v

-

( )

O t

v

( )

C2 t

-

R

on

R

L2

Figure 27. SEPIC Simplified Schematic

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

I_L2= (I_LED

)

(63)

(64)

and

I_L1= (I_LED) x (D/D')

≈

’

÷

∆

1

V_OUT

V_IN

D

≈

’

∆

÷

= ∆

÷

∆

'

2

D

≈

∆

’

≈

∆

’

÷

«

◊

≈

V_D

’

÷

◊

R

L1

R_L2

R

D

≈

∆

’

÷

D

≈

∆

’

÷

ON

÷

∆

+

1+

+

∆

2

∆

«

÷

◊

∆

«

÷

◊

'

R

V_OUT

«

◊

«

◊

«

D

∆

«

÷

◊

(65)

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V_OUT

R_OUT

=

I_LED

(66)

Therefore:

≈

’

÷

∆

1

∆

÷

h =

∆

2

≈

∆

’

÷

≈

∆

’

÷

≈

∆

«

V_D

’

÷

R

L1

R_L2

D

2

≈

∆

’

÷

D

≈

’

ON

+

∆

÷

1+

+

∆

«

÷

◊

∆

«

÷

◊

V_OUTR_OUT

'

R_OUT

'

R_OUT

« ◊

«

◊

D

∆

«

÷

◊

(67)

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.

V_OUT

≈

’

÷

D

x h

=

∆

V_IN

1 - D

«

◊

(68)

(69)

V_OUT

’

÷

◊

≈

D =

∆

(V x h) +V_OUT

IN

«

Table 7. Efficiencies for Typical SEPIC Applications

V_IN

V_OUT

I_IN

2.7V

3.1V

V_IN

V_OUT

I_IN

3.3V

3.1V

V_IN

V_OUT

I_IN

5V

3.1V

770mA

500mA

75%

600mA

500mA

80%

375mA

500mA

83%

I_LED

η

I_LED

η

I_LED

η

SEPIC Converter PCB Layout

The layout guidelines described for the LM3410 Boost-Converter are applicable to the SEPIC OLED Converter.

Figure 28 is a proper PCB layout for a SEPIC Converter.

LED₁

V_O

PGND

C₂

R₁

L₂

FB

DIM

D₁

4

3

2

1

AGND

5

VIN

C₁

C₃

6

PGND

SW

VIN

L₁

Figure 28. HB/OLED SEPIC PCB Layout

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LM3410X SOT-23 Design Example 1: 5 x 1206 Series LED String Application

D

1

L

1

LEDs

V_IN

LM3410

DIMM

C

1

4

5

3

2

1

R

2

C

2

R

1

Figure 29. LM3410X (1.6MHz): V_IN= 2.7V to 5.5V, 5 x 3.3V LEDs, (V_OUT≊ 16.5V) I_LED≊ 50mA

Part ID

Part Value

2.8A I_SWLED Driver

10µF, 6.3V, X5R

2.2µF, 25V, X5R

0.4V_fSchottky 500mA, 30V_R

10µH 1.2A

Manufacturer

TI

Part Number

LM3410XMF

U1

C1, Input Cap

C2 Output Cap

D1, Catch Diode

L1

TDK

C2012X5R0J106M

C2012X5R1E225M

MBR0530

TDK

Diodes Inc

Coilcraft

Vishay

Lite-On

DO1608C-103

CRCW08054R02F

CRCW08051003F

LTW-150k

R1

4.02Ω, 1%

R2

100kΩ, 1%

LED's

SMD-1206, 50mA, V_f≊ 3 .6V

Submit Documentation Feedback

27

Product Folder Links: LM3410 LM3410Q

LM3410, LM3410Q

SNVS541G –OCTOBER 2007–REVISED MAY 2013

www.ti.com

LM3410Y SOT-23 Design Example 2: 5 x 1206 Series LED String Application

D

1

L

1

LEDs

V_IN

LM3410

DIMM

C

1

4

5

3

2

1

R

2

C

2

R

1

Figure 30. LM3410Y (525kHz): V_IN= 2.7V to 5.5V, 5 x 3.3V LEDs, (V_OUT≊ 16.5V) I_LED≊ 50mA

Part ID

Part Value

2.8A I_SWLED Driver

10µF, 6.3V, X5R

2.2µF, 25V, X5R

0.4V_fSchottky 500mA, 30V_R

15µH 1.2A

Manufacturer

TI

Part Number

LM3410YMF

U1

C1, Input Cap

C2 Output Cap

D1, Catch Diode

L1

TDK

C2012X5R0J106M

C2012X5R1E225M

MBR0530

TDK

Diodes Inc

Coilcraft

Vishay

Lite-On

DO1608C-153

CRCW08054R02F

CRCW08051003F

LTW-150k

R1

4.02Ω, 1%

R2

100kΩ, 1%

LED's

SMD-1206, 50mA, V_f≊ 3 .6V

28

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Product Folder Links: LM3410 LM3410Q

LM3410, LM3410Q

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SNVS541G –OCTOBER 2007–REVISED MAY 2013

LM3410X WSON Design Example 3: 7 LEDs x 5 LED String Backlighting Application

LEDs

L

D

1

V_IN

LM3410

C

R

1

2

3

6

5

4

1

2

I

LED

C

2

DIMM

I

SET

R

1

Figure 31. LM3410X (1.6MHz): V_IN= 2.7V to 5.5V, 7 x 5 x 3.3V LEDs, (V_OUT≊ 16.7V), I_LED≊ 25mA

Part ID

Part Value

2.8A I_SWLED Driver

10µF, 6.3V, X5R

4.7µF, 25V, X5R

0.4V_fSchottky 500mA, 30V_R

8.2µH, 2A

Manufacturer

TI

Part Number

LM3410XSD

U1

C1, Input Cap

C2 Output Cap

D1, Catch Diode

L1

TDK

C2012X5R0J106M

C2012X5R1E475M

MBR0530

TDK

Diodes Inc

Coilcraft

Vishay

Lite-On

MSS6132-822ML

CRCW08051R15F

CRCW08051003F

LTW-150k

R1

1.15Ω, 1%

R2

100kΩ, 1%

LED's

SMD-1206, 50mA, V_f≊ 3 .6V

Submit Documentation Feedback

29

Product Folder Links: LM3410 LM3410Q

LM3410, LM3410Q

SNVS541G –OCTOBER 2007–REVISED MAY 2013

www.ti.com

LM3410X WSON Design Example 4: 3 x HB LED String Application

L

1

D

1

V_IN

LM3410

C

1

HB - LEDs

1

2

3

6

5

4

R

2

C

2

DIMM

R

3

R

1

Figure 32. LM3410X (1.6MHz): V_IN= 2.7V to 5.5V, 3 x 3.4V LEDs, (V_OUT≊ 11V) I_LED≊ 340mA

Part ID

Part Value

2.8A I_SWLED Driver

10µF, 6.3V, X5R

2.2µF, 25V, X5R

0.4V_fSchottky 500mA, 30V_R

10µH 1.2A

Manufacturer

TI

Part Number

LM3410XSD

U1

C1, Input Cap

C2 Output Cap

D1, Catch Diode

L1

TDK

C2012X5R0J106M

C2012X5R1E225M

MBR0530

TDK

Diodes Inc

Coilcraft

Vishay

CREE

DO1608C-103

R1

1.00Ω, 1%

CRCW08051R00F

CRCW08051003F

CRCW08051R50F

XREWHT-L1-0000-0901

R2

100kΩ, 1%

R3

1.50Ω, 1%

HB - LED's

340mA, V_f≊ 3 .6V

30

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LM3410, LM3410Q

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SNVS541G –OCTOBER 2007–REVISED MAY 2013

LM3410Y SOT-23 Design Example 5: 5 x 1206 Series LED String Application with OVP

LEDs

L

D

1

V

IN

DIMM

LM3410

C

1

OVP

4

5

3

2

1

C

2

R

2

D

2

R

3

R

1

Figure 33. LM3410Y (525kHz): V_IN= 2.7V to 5.5V, 5 x 3.3V LEDs, (V_OUT≊ 16.5V) I_LED≊ 50mA

Part ID

Part Value

2.8A I_SWLED Driver

10µF, 6.3V, X5R

2.2µF, 25V, X5R

0.4V_fSchottky 500mA,

18V Zener diode

15µH, 0.70A

Manufacturer

TI

Part Number

LM3410YMF

U1

C1 Input Cap

TDK

C2012X5R0J106M

C2012X5R1E225M

MBR0530

C2 Output Cap

TDK

D1, Catch Diode

Diodes Inc

TDK

D2

L1

1N4746A

VLS4012T-150MR65

CRCW08054R02F

CRCW08051003F

CRCW06031000F

LTW-150k

R1

4.02Ω, 1%

Vishay

Lite-On

R2

100kΩ, 1%

R3

100Ω, 1%

LED’s

SMD-1206, 50mA, V_f≊ 3 .6V

Submit Documentation Feedback

31

Product Folder Links: LM3410 LM3410Q

LM3410, LM3410Q

SNVS541G –OCTOBER 2007–REVISED MAY 2013

www.ti.com

LM3410X SEPIC WSON Design Example 6: HB/OLED Illumination Application

V

IN

V

O

L

1

C

3

D

1

LM3410

C

1

C

2

L

2

HB/OLED

1

2

3

6

5

4

R

2

R

1

Figure 34. LM3410X (1.6MHz): V_IN= 2.7V to 5.5V, (V_OUT≊ 3.8V) I_LED≊ 300mA

Part ID

U1

Part Value

2.8A I_SWLED Driver

10µF, 6.3V, X5R

2.2µF, 25V, X5R

0.4V_f, Schottky 1A, 20V_R

4.7µH 3A

Manufacturer

TI

Part Number

LM3410XSD

C2012X5R0J106K

C2012X5R1E225M

DFLS120L

C1 Input Cap

C2 Output Cap

C3 Cap

TDK

D1, Catch Diode

L1 and L2

R1

Diodes Inc

Coilcraft

Vishay

CREE

MSS6132-472

665 mΩ, 1%

CRCW0805R665F

CRCW08051003F

XREWHT-L1-0000-0901

R2

100kΩ, 1%

HB - LED’s

350mA, V_f≊ 3 .6V

32

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Product Folder Links: LM3410 LM3410Q

LM3410, LM3410Q

www.ti.com

SNVS541G –OCTOBER 2007–REVISED MAY 2013

LM3410X WSON Design Example 7: Boost Flash Application

V

IN

V_O

L

1

D

1

C

1

LM3410

LEDs

C

2

1

2

3

6

5

4

FLASH CTRL

R

1

Figure 35. LM3410X (1.6MHz): V_IN= 2.7V to 5.5V, (V_OUT≊ 8V) I_LED≊ 1.0A Pulsed

Part ID

U1

Part Value

2.8A I_SWLED Driver

10µF, 6.3V, X5R

Manufacturer

TI

Part Number

LM3410XSD

C1 Input Cap

C2 Output Cap

D1, Catch Diode

L1

TDK

C2012X5R0J106M

C2012X5R1A106M

MBR0530

10µF,16V, X5R

TDK

0.4V_fSchottky 500mA, 30V_R

4.7µH, 3A

Diodes Inc

Coilcraft

Vishay

CREE

MSS6132-472

R1

200mΩ, 1%

CRCW0805R200F

XREWHT-L1-0000-0901

LED’s

500mA, V_f≊ 3 .6V, I_PULSE= 1.0A

Submit Documentation Feedback

33

Product Folder Links: LM3410 LM3410Q

LM3410, LM3410Q

SNVS541G –OCTOBER 2007–REVISED MAY 2013

www.ti.com

LM3410X SOT-23 Design Example 8: 5 x 1206 Series LED String Application with VIN > 5.5V

L

1

D

1

LEDs

V_PWR

DIMM

LM3410

C

1

R

3

4

5

3

2

1

R

2

C

2

D

2

C

3

R

1

Figure 36. LM3410X (1.6MHz): V_PWR= 9V to 14V, (V_OUT≊ 16.5V) I_LED≊ 50mA

Part ID

Part Value

2.8A I_SWLED Driver

10µF, 6.3V, X5R

2.2µF, 25V, X5R

0.1µF, 6.3V, X5R

0.43V_f, Schotky, 0.5A, 30V_R

10µH 1.2A

Mfg

TI

Part Number

LM3410XMF

U1

C1 Input V_PWRCap

TDK

C2012X5R0J106M

C2012X5R1E225M

C1005X5R1C104K

MBR0530

C2 Output Cap

TDK

C2 Input V_INCap

TDK

D1, Catch Diode

Diodes Inc

Coilcraft

Vishay

Diodes Inc

Lite-On

L1

R1

DO1608C-103

CRCW08054R02F

CRCW08051003F

CRCW08055760F

BZX84C3V3

4.02Ω, 1%

R2

100kΩ, 1%

R3

576Ω, 1%

D2

3.3V Zener, SOT-23

SMD-1206, 50mA, V_f≊ 3 .6V

LED’s

LTW-150k

34

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Product Folder Links: LM3410 LM3410Q

LM3410, LM3410Q

www.ti.com

SNVS541G –OCTOBER 2007–REVISED MAY 2013

LM3410X WSON Design Example 9: Camera Flash or Strobe Circuit Application

V

IN

V

O

L

1

D

1

C

3

C

1

LM3410

LED(s)

L

2

C

2

1

2

3

6

5

4

R

2

Q

2

R

3

1

R

4

Q

1

FLASH CTRL

Figure 37. LM3410X (1.6MHz): V_IN= 2.7V to 5.5, (V_OUT≊ 7.5V), I_LED≊ 1.5A Flash

Part ID

U1

Part Value

2.8A I_SWLED Driver

10µF, 6.3V, X5R

220µF, 10V, Tanatalum

10µF, 16V, X5R

0.43V_f, Schotky, 1.0A, 20V_R

3.3µH 2.7A

Mfg

TI

Part Number

LM3410XSD

C1 Input V_PWRCap

TDK

C1608X5R0J106K

T491V2271010A2

C3216X5R0J106K

DFLS120L

C2 Output Cap

KEMET

TDK

C3 Cap

D1, Catch Diode

Diodes Inc

Coilcraft

Vishay

ZETEX

CREE

L1

R1

MOS6020-332

1.0kΩ, 1%

CRCW08051001F

CRCW08053742F

CRCW08051003F

CRCW0805R150F

ZXMN3A14F

R2

37.4kΩ, 1%

R3

100kΩ, 1%

R4

0.15Ω, 1%

Q1, Q2

LED’s

30V, I_D= 3.9A

500mA, V_f≊ 3 .6V, I_PULSE= 1.5A

XREWHT-L1-0000-00901

Submit Documentation Feedback

35

Product Folder Links: LM3410 LM3410Q

LM3410, LM3410Q

SNVS541G –OCTOBER 2007–REVISED MAY 2013

www.ti.com

LM3410X SOT-23 Design Example 10: 5 x 1206 Series LED String Application with V_INand V_PWR

Rail > 5.5V

L

D

LEDs

1

V_PWR

LM3410

DIMM

C

1

4

5

3

2

1

R

2

C

2

V_IN

C

3

R

1

Figure 38. LM3410X (1.6MHz): V_PWR= 9V to 14V, V_IN= 2.7V to 5.5V, (V_OUT≊ 16.5V) I_LED≊ 50mA

Part ID

Part Value

2.8A I_SWLED Driver

10µF, 6.3V, X5R

2.2µF, 25V, X5R

0.1µF, 6.3V, X5R

0.43V_f, Schotky, 0.5A, 30V_R

10µH 1.5A

Mfg

TI

Part Number

LM3410XMF

U1

C1 Input V_PWRCap

C2 V_OUTCap

C3 Input V_INCap

D1, Catch Diode

L1

TDK

C2012X5R0J106M

C2012X5R1E225M

C1005X5R1C104K

MBR0530

TDK

Diodes Inc

Coilcraft

Vishay

Lite-On

DO1608C-103

CRCW08054R02F

CRCW08051003F

LTW-150k

R1

4.02Ω, 1%

R2

100kΩ, 1%

LED’s

SMD-1206, 50mA, V_f≊ 3 .6V

36

Submit Documentation Feedback

Product Folder Links: LM3410 LM3410Q

LM3410, LM3410Q

www.ti.com

SNVS541G –OCTOBER 2007–REVISED MAY 2013

LM3410X WSON Design Example 11: Boot-Strap Circuit to Extend Battery Life

V

IN

V

O

L

D

1

C

1

4

D

2

C

1

LM3410

L

2

1

2

3

6

5

4

C

2

C

3

R

3

D

3

R

1

Figure 39. LM3410X (1.6MHz): V_IN= 1.9V to 5.5V, V_IN> 2.3V (TYP) for Startup, I_LED≊ 300mA

Part ID

U1

Part Value

2.8A I_SWLED Driver

10µF, 6.3V, X5R

0.1µF, 6.3V, X5R

0.43V_f, Schotky, 1.0A, 20V_R

Dual Small Signal Schotky

3.3µH 3A

Mfg

TI

Part Number

LM3410XSD

C1 Input V_PWRCap

C2 V_OUTCap

C3 Input V_INCap

D1, Catch Diode

D2, D3

TDK

C1608X5R0J106K

C1005X5R1C104K

DFLS120L

TDK

Diodes Inc

Coilcraft

Vishay

BAT54CT

L1, L2

MOS6020-332

CRCW0805R665F

CRCW08051003F

OVSPWBCR44

R1

665 mΩ, 1%

R3

100kΩ, 1%

Vishay

HB/OLED

3.4V_f, 350mA

TT Electronics/Optek

Submit Documentation Feedback

37

Product Folder Links: LM3410 LM3410Q

LM3410, LM3410Q

SNVS541G –OCTOBER 2007–REVISED MAY 2013

www.ti.com

REVISION HISTORY

Changes from Revision F (May 2013) to Revision G

Page

•

Changed layout of National Data Sheet to TI format .......................................................................................................... 37

38

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Product Folder Links: LM3410 LM3410Q

PACKAGE MATERIALS INFORMATION

www.ti.com

11-Oct-2013

TAPE AND REEL INFORMATION

*All dimensions are nominal

Device

Package Package Pins

Type Drawing

SPQ

Reel

A0

B0

K0

P1

W

Pin1

Diameter Width (mm) (mm) (mm) (mm) (mm) Quadrant

(mm) W1 (mm)

LM3410XMF/NOPB

LM3410XMFE/NOPB

LM3410XMFX/NOPB

LM3410XMY/NOPB

SOT-23

DBV

DGN

5

8

1000

250

178.0

8.4

3.2

5.3

3.2

3.4

1.4

4.0

8.0

Q3

Q1

3000

1000

8.4

8.0

MSOP-

Power

PAD

12.4

12.0

LM3410XMYE/NOPB

LM3410XMYX/NOPB

LM3410XQMF/NOPB

MSOP-

Power

PAD

DGN

8

250

178.0

330.0

12.4

5.3

3.4

1.4

8.0

12.0

Q1

MSOP-

Power

PAD

3500

SOT-23

DBV

NGG

DBV

5

6

5

1000

3000

1000

250

178.0

330.0

178.0

8.4

3.2

3.3

3.2

3.3

3.2

1.4

1.0

1.4

4.0

8.0

4.0

8.0

Q3

Q1

Q3

LM3410XQMFX/NOPB SOT-23

LM3410XSD/NOPB

LM3410XSDE/NOPB

LM3410XSDX/NOPB

LM3410YMF/NOPB

LM3410YMFE/NOPB

LM3410YMFX/NOPB

WSON

SOT-23

12.4

8.4

12.0

8.0

4500

1000

250

8.4

8.0

3000

8.4

8.0

Pack Materials-Page 1

PACKAGE MATERIALS INFORMATION

www.ti.com

11-Oct-2013

Device

Package Package Pins

Type Drawing

SPQ

1000

250

Reel

A0

B0

K0

P1

W

Pin1

Diameter Width (mm) (mm) (mm) (mm) (mm) Quadrant

(mm) W1 (mm)

LM3410YMY/NOPB

LM3410YMYE/NOPB

LM3410YMYX/NOPB

LM3410YQMF/NOPB

MSOP-

Power

PAD

DGN

8

178.0

330.0

12.4

5.3

3.4

1.4

8.0

12.0

Q1

MSOP-

Power

PAD

MSOP-

Power

PAD

3500

SOT-23

DBV

NGG

5

6

1000

3000

1000

250

178.0

330.0

8.4

3.2

3.3

3.2

3.3

1.4

1.0

4.0

8.0

Q3

Q1

LM3410YQMFX/NOPB SOT-23

LM3410YSD/NOPB

LM3410YSDE/NOPB

LM3410YSDX/NOPB

WSON

12.4

12.0

4500

*All dimensions are nominal

Device

Package Type Package Drawing Pins

SPQ

Length (mm) Width (mm) Height (mm)

LM3410XMF/NOPB

LM3410XMFE/NOPB

LM3410XMFX/NOPB

LM3410XMY/NOPB

LM3410XMYE/NOPB

SOT-23

DBV

DGN

5

8

1000

250

210.0

185.0

35.0

SOT-23

3000

1000

250

MSOP-PowerPAD

Pack Materials-Page 2

PACKAGE MATERIALS INFORMATION

www.ti.com

11-Oct-2013

Device

Package Type Package Drawing Pins

SPQ

Length (mm) Width (mm) Height (mm)

LM3410XMYX/NOPB

LM3410XQMF/NOPB

LM3410XQMFX/NOPB

LM3410XSD/NOPB

LM3410XSDE/NOPB

LM3410XSDX/NOPB

LM3410YMF/NOPB

LM3410YMFE/NOPB

LM3410YMFX/NOPB

LM3410YMY/NOPB

LM3410YMYE/NOPB

LM3410YMYX/NOPB

LM3410YQMF/NOPB

LM3410YQMFX/NOPB

LM3410YSD/NOPB

LM3410YSDE/NOPB

LM3410YSDX/NOPB

MSOP-PowerPAD

SOT-23

DGN

DBV

NGG

DBV

DGN

DBV

NGG

8

5

6

5

8

5

6

3500

1000

3000

1000

250

367.0

210.0

367.0

210.0

367.0

210.0

367.0

185.0

367.0

185.0

367.0

185.0

367.0

35.0

SOT-23

WSON

4500

1000

250

SOT-23

3000

1000

250

MSOP-PowerPAD

SOT-23

3500

1000

3000

1000

250

SOT-23

WSON

4500

Pack Materials-Page 3

MECHANICAL DATA

DGN0008A

MUY08A (Rev A)

BOTTOM VIEW

www.ti.com

MECHANICAL DATA

NGG0006A

SDE06A (Rev A)

www.ti.com

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e2e.ti.com

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Mailing Address: Texas Instruments, Post Office Box 655303, Dallas, Texas 75265


型号：	LM3410XMY
厂家：	TEXAS INSTRUMENTS
描述：	525kHz/1.6MHz, Constant Current Boost and SEPIC LED Driver with Internal Compensation 525kHz / 1.6MHz的，恒流升压和SEPIC LED驱动器，具有内部补偿驱动器
文件：	总49页 (文件大小：1398K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

LM3410XMY [TI]

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