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LM3405

VIN VIN

EN/DIM

BOOST

GND

C3 L1

OFF C4

VOUT

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An IMPORTANT NOTICE at the end of this data sheet addresses availability, warranty, changes, use in safety-critical applications,

intellectual property matters and other important disclaimers. PRODUCTION DATA.

LM3405

SNVS429C –OCTOBER 2006–REVISED DECEMBER 2016

LM3405 1.6-MHz, 1-A Constant Current Buck Regulator For Powering LEDS

1 Features

1• VIN Operating Range of 3 V to 15 V

• Drives up to 5 High-Brightness LEDs in Series at

1 A

• Thin SOT-6 Package

• 1.6-MHz Switching Frequency

• EN/DIM Input for Enabling and PWM Dimming of

LEDs

• 300-mΩNMOS Switch

• 40-nA Shutdown Current at VIN =5V

• Internally Compensated Current-mode Control

• Cycle-by-Cycle Current Limit

• Input Voltage UVLO

• Overcurrent Protection

• Thermal Shutdown

2 Applications

• LED Drivers

• Constant Current Sources

• Industrial Lighting

• LED Flashlights

3 Description

The LM3405 is a 1-A constant current buck LED

driver designed to provide a simple, high efficiency

solution for driving high power LEDs. With a 0.205-V

reference voltage feedback control to minimize power

dissipation, an external resistor sets the current as

required for driving various types of LEDs. Switching

frequency is internally set to 1.6 MHz, allowing small

surface mount inductors and capacitors to be used.

The LM3405 uses current-mode control and internal

compensation offering ease of use and predictable,

high performance regulation over a wide range of

operating conditions. With a maximum input voltage

of 15 V, the device can drive up to 3 High-Brightness

LEDs in series at 1-A forward current, with the single

LED forward voltage of approximately 3.7 V.

Additional features include user accessible EN/DIM

pin for enabling and PWM dimming of LEDs, thermal

shutdown, cycle-by-cycle current limit and overcurrent

protection.

Device Information(1)

PART NUMBER PACKAGE BODY SIZE (NOM)

LM3405 SOT (6) 2.90 mm × 1.60 mm

(1) For all available packages, see the orderable addendum at

the end of the data sheet.

Typical Application Circuit Efficiency vs LED Current (VIN = 5 V)

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Table of Contents

1 Features.................................................................. 1

2 Applications ........................................................... 1

3 Description............................................................. 1

4 Revision History..................................................... 2

5 Pin Configuration and Functions......................... 3

6 Specifications......................................................... 4

6.1 Absolute Maximum Ratings ..................................... 4

6.2 ESD Ratings.............................................................. 4

6.3 Recommended Operating Conditions....................... 4

6.4 Thermal Information.................................................. 5

6.5 Electrical Characteristics........................................... 5

6.6 Typical Characteristics.............................................. 6

7 Detailed Description.............................................. 8

7.1 Overview................................................................... 8

7.2 Functional Block Diagram......................................... 9

7.3 Feature Description................................................... 9

7.4 Device Functional Modes........................................ 14

8 Application and Implementation ........................ 15

8.1 Application Information............................................ 15

8.2 Typical Applications ................................................ 19

8.3 System Examples ................................................... 21

9 Power Supply Recommendations...................... 24

10 Layout................................................................... 24

10.1 Layout Guidelines ................................................. 24

10.2 Layout Example .................................................... 24

11 Device and Documentation Support................. 25

11.1 Documentation Support ........................................ 25

11.2 Receiving Notification of Documentation Updates 25

11.3 Community Resource............................................ 25

11.4 Trademarks........................................................... 25

11.5 Electrostatic Discharge Caution............................ 25

11.6 Glossary................................................................ 25

12 Mechanical, Packaging, and Orderable

Information........................................................... 25

4 Revision History

NOTE: Page numbers for previous revisions may differ from page numbers in the current version.

Changes from Revision B (April 2013) to Revision C Page

• Added ESD Ratings table, Feature Description section, Device Functional Modes,Application and Implementation

section, Power Supply Recommendations section, Layout section, Device and Documentation Support section, and

Mechanical, Packaging, and Orderable Information section ................................................................................................. 1

• Deleted Soldering information (220°C, maximum) from Absolute Maximum Ratings............................................................ 4

• Changed Thermal resistance, θJA, in Thermal Information From: 118°C/W To: 182.9°C/W.................................................. 5

Changes from Revision A (May 2013) to Revision B Page

• Changed layout of National Semiconductor Data Sheet to TI format .................................................................................. 23

BOOST

GND

VIN

EN/DIM

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5 Pin Configuration and Functions

DDC Package

6-Pin SOT

Top View

DDC Package

6-Pin SOT

Pin 1 Identification

Pin Functions

PIN I/O DESCRIPTION

NO. NAME

1 BOOST O Boost voltage that drives the NMOS output switch. A bootstrap capacitor is connected between the

BOOST and SW pins.

2 GND — Signal and power ground pin. Place the bottom resistor of the feedback network as close as possible

to this pin.

3 FB I Feedback pin. Connect FB to the LED string cathode and an external resistor to ground to set the

LED current.

4 EN/DIM I Enable control input. Logic high enables operation. Toggling this pin with a periodic logic square

wave of varying duty cycle at different frequencies controls the brightness of LEDs. Do not allow this

pin to float or be greater than VIN + 0.3 V.

5 VIN I Input supply voltage. Connect a bypass capacitor locally from this pin to GND.

6 SW O Switch pin. Connect this pin to the inductor, catch diode, and bootstrap capacitor.

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(1) Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings

only, which do not imply functional operation of the device at these or any other conditions beyond those indicated under Recommended

Operating Conditions. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.

6 Specifications

6.1 Absolute Maximum Ratings

over operating free-air temperature range (unless otherwise noted)(1)

MIN MAX UNIT

Input voltage, VIN –0.5 20 V

SW voltage –0.5 20 V

Boost voltage –0.5 26 V

Boost to SW voltage –0.5 6 V

FB voltage –0.5 3 V

EN/DIM voltage –0.5 (VIN + 0.3) V

Junction temperature, TJ150 °C

Storage temperature, Tstg –65 150 °C

(1) JEDEC document JEP155 states that 500-V HBM allows safe manufacturing with a standard ESD control process.

(2) JEDEC document JEP157 states that 250-V CDM allows safe manufacturing with a standard ESD control process.

6.2 ESD Ratings VALUE UNIT

V(ESD) Electrostatic discharge Human-body model (HBM), per ANSI/ESDA/JEDEC JS-001(1) ±2000 V

Charged-device model (CDM), per JEDEC specification JESD22-C101(2) ±1000

6.3 Recommended Operating Conditions

MIN MAX UNIT

Input voltage, VIN 3 15 V

EN/DIM voltage 0 (VIN + 0.3) V

Boost to SW voltage 2.5 5.5 V

Junction temperature, TJ–40 125 °C

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(1) For more information about traditional and new thermal metrics, see the Semiconductor and IC Package Thermal Metrics application

report.

6.4 Thermal Information

THERMAL METRIC(1)

LM3405

UNIT

DDC

(SOT)

6 PINS

RθJA Junction-to-ambient thermal resistance 182.9 °C/W

RθJC(top) Junction-to-case (top) thermal resistance 53.4 °C/W

RθJB Junction-to-board thermal resistance 28.1 °C/W

ψJT Junction-to-top characterization parameter 1.2 °C/W

ψJB Junction-to-board characterization parameter 27.7 °C/W

RθJC(bot) Junction-to-case (bottom) thermal resistance — °C/W

6.5 Electrical Characteristics

VIN = 12 V, typical values are for TJ= 25°C only; minimum and maximum limits apply over the junction temperature (TJ) range

of –40°C to 125°C (unless otherwise noted). Typical values represent the most likely parametric norm, and are provided for

reference purposes only.

PARAMETER TEST CONDITIONS MIN TYP MAX UNIT

VFB Feedback voltage 0.188 0.205 0.22 V

ΔVFB/(ΔVIN×VFB) Feedback voltage line regulation VIN = 3 V to 15 V 0.01% V

IFB Feedback input bias current Sink or source 10 250 nA

UVLO Undervoltage lockout VIN rising 2.74 2.95 V

VIN falling 1.9 2.3

UVLO hysteresis 0.44 V

fSW Switching frequency 1.2 1.6 1.9 MHz

DMAX Maximum duty cycle VFB = 0 V 85% 94%

RDS(ON) Switch ON resistance VBOOST – VSW = 3 V 300 600 mΩ

ICL Switch current limit VBOOST – VSW = 3 V, VIN = 3 V 1.2 2 2.8 A

IQQuiescent current Switching, VFB = 0.195 V 1.8 2.8 mA

Quiescent current (shutdown) VEN/DIM = 0 V 0.3 µA

VEN/DIM_TH Enable threshold voltage VEN/DIM rising 1.8 V

Shutdown threshold voltage VEN/DIM falling 0.4 V

IEN/DIM EN/DIM pin current Sink or source 0.01 µA

ISW Switch leakage VIN = 15 V 0.1 µA

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6.6 Typical Characteristics

VIN = 12 V, VBOOST – VSW = 5 V, and TA= 25°C (unless otherwise noted).

Figure 1. Efficiency vs LED Current

IF= 1 A

Figure 2. Efficiency vs Input Voltage

IF= 0.7 A

Figure 3. Efficiency vs Input Voltage

IF= 0.35 A

Figure 4. Efficiency vs Input Voltage

Figure 5. VFB vs Temperature Figure 6. Oscillator Frequency vs Temperature

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Typical Characteristics (continued)

VIN = 12 V, VBOOST – VSW = 5 V, and TA= 25°C (unless otherwise noted).

Figure 7. Current Limit vs Temperature

VBOOST – VSW = 3 V

Figure 8. SOT RDS(ON) vs Temperature

Figure 9. Quiescent Current vs Temperature

VIN = 15 V IF= 0.2 A

Figure 10. Start-Up Response to EN/DIM Signal

VIN

-VD1

TON

Inductor

Current

D = TON/TSW

VSW

TOFF

TSW

Voltage

'iL

ILPK

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7 Detailed Description

7.1 Overview

The LM3405 device is a PWM, current-mode controlled buck switching regulator designed to provide a simple,

high efficiency solution for driving LEDs with a preset switching frequency of 1.6MHz. This high frequency allows

the LM3405 to operate with small surface mount capacitors and inductors, resulting in LED drivers that only

require a minimum amount of board space. The LM3405 is internally compensated, simple to use, and requires

few external components.

The following sections refer to Functional Block Diagram and to the waveforms in Figure 11. The LM3405

supplies a regulated output current by switching the internal NMOS power switch at constant frequency and

variable duty cycle. A switching cycle begins at the falling edge of the reset pulse generated by the internal

oscillator. When this pulse goes low, the output control logic turns on the internal NMOS power switch. During

this on-time, the SW pin voltage (VSW) swings up to approximately VIN, and the inductor current (IL) increases

with a linear slope. ILis measured by the current sense amplifier, which generates an output proportional to the

switch current. The sense signal is summed with the regulator’s corrective ramp and compared to the error

amplifier’s output, which is proportional to the difference between the feedback voltage and VREF. When the

PWM comparator output goes high, the internal power switch turns off until the next switching cycle begins.

During the switch off-time, inductor current discharges through the catch diode D1, which forces the SW pin to

swing below ground by the forward voltage (VD1) of the catch diode. The regulator loop adjusts the duty cycle (D)

to maintain a constant output current (IF) through the LED, by forcing FB pin voltage to be equal to VREF

(0.205 V).

Figure 11. SW Pin Voltage and Inductor Current Waveforms of LM3405

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7.2 Functional Block Diagram

7.3 Feature Description

7.3.1 Boost Function

Capacitor C3 and diode D2 in the Functional Block Diagram are used to generate a voltage VBOOST. The voltage

across C3, VBOOST – VSW, is the gate drive voltage to the internal NMOS power switch. To properly drive the

internal NMOS switch during its on-time, VBOOST must be at least 2.5-V greater than VSW. TI recommends a large

value of VBOOST – VSW to achieve better efficiency by minimizing both the internal switch ON resistance (RDS(ON))

and the switch rise and fall times. However, VBOOST – VSW must not exceed the maximum operating limit of 5.5 V.

When the LM3405 starts up, internal circuitry from VIN supplies a 20-mA current to the BOOST pin, flowing out of

the BOOST pin into C3. This current charges C3 to a voltage sufficient to turn the switch on. The BOOST pin

continues to source current to C3 until the voltage at the feedback pin is greater than 123 mV.

There are various methods to derive VBOOST:

1. From the input voltage (VIN)

2. From the output voltage (VOUT)

3. From a shunt or series Zener diode

4. From an external distributed voltage rail (VEXT)

The first method is shown in Functional Block Diagram. Capacitor C3 is charged through diode D2 by VIN. During

a normal switching cycle, when the internal NMOS power switch is off, TOFF (see Figure 11), VBOOST equals VIN

minus the forward voltage of D2 (VD2), during which the current in the inductor (L1) forward biases the catch

diode D1 (VD1). Therefore, the gate drive voltage stored across C3 is shown in Equation 1.

VBOOST – VSW = VIN – VD2 + VD1 (1)

When the NMOS switch turns on (TON), the switch pin rises to Equation 2.

VSW = VIN – (RDS(ON) × IL) (2)

Because the voltage across C3 remains unchanged, VBOOST is forced to rise thus reverse biasing D2. The

voltage at VBOOST is then calculated with Equation 3.

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Feature Description (continued)

VBOOST = 2VIN – (RDS(ON) × IL) – VD2 + VD1 (3)

Depending on the quality of the diodes D1 and D2, the gate drive voltage in this method can be slightly less or

larger than the input voltage VIN. For best performance, ensure that the variation of the input supply does not

cause the gate drive voltage to fall outside the recommended range in Equation 4.

2.5 V < VIN – VD2 + VD1 < 5.5 V (4)

The second method for deriving the boost voltage is to connect D2 to the output as shown in Figure 12. The gate

drive voltage in this configuration is shown in Equation 5.

VBOOST – VSW = VOUT – VD2 + VD1 (5)

Because the gate drive voltage must be in the range of 2.5 V to 5.5 V, the output voltage VOUT must be limited to

a certain range. For the calculation of VOUT, see Output Voltage.

Figure 12. VBOOST Derived from VOUT

The third method can be used in the applications where both VIN and VOUT are greater than 5.5 V. In these

cases, C3 cannot be charged directly from these voltages; instead C3 can be charged from VIN or VOUT minus a

Zener voltage (VD3) by placing a Zener diode D3 in series with D2 as shown in Figure 13. When using a series

Zener diode from the input, the gate drive voltage is VIN – VD3 – VD2 + VD1.

Figure 13. VBOOST Derived from VIN Through a Series Zener

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Feature Description (continued)

An alternate method is to place the Zener diode D3 in a shunt configuration as shown in Figure 14. A small,

350-mW to 500-mW, 5.1-V Zener in a SOT or SOD package can be used for this purpose. A small ceramic

capacitor such as a 6.3-V, 0.1-µF capacitor (C5) must be placed in parallel with the Zener diode. When the

internal NMOS switch turns on, a pulse of current is drawn to charge the internal NMOS gate capacitance. The

0.1-µF parallel shunt capacitor ensures that the VBOOST voltage is maintained during this time. Resistor R2 must

be chosen to provide enough RMS current to the Zener diode and to the BOOST pin. TI's recommended choice

for the Zener current (IZENER) is 1 mA. The current IBOOST into the BOOST pin supplies the gate current of the

NMOS power switch. It reaches a maximum of around 3.6 mA at the highest gate drive voltage of 5.5 V over the

LM3405 operating range.

For the worst case IBOOST, increase the current by 50%. In that case, the maximum boost current is Equation 6.

IBOOST-MAX = 1.5 × 3.6 mA = 5.4 mA (6)

R2 is calculated with Equation 7.

R2 = (VIN – VZENER) / (IBOOST_MAX + IZENER) (7)

For example, let VIN = 12 V, VZENER = 5V, IZENER = 1 mA, then calculate Equation 8.

R2 = (12 V – 5 V) / (5.4 mA + 1 mA) = 1.09 kΩ(8)

Figure 14. VBOOST Derived from VIN Through a Shunt Zener

The fourth method can be used in an application which has an external low voltage rail, VEXT. C3 can be charged

through D2 from VEXT, independent of VIN and VOUT voltage levels. Again for best performance, ensure that the

gate drive voltage, VEXT – VD2 + VD1, falls in the range of 2.5 V to 5.5 V.

7.3.2 Setting the LED Current

LM3405 is a constant current buck regulator. The LEDs are connected between VOUT and the FB pin as shown in

the Typical Applications. The FB pin is at 0.205 V in regulation and therefore the LED current IFis set by VFB and

resistor R1 from FB to ground by Equation 9.

IF= VFB / R1 (9)

IFmust not exceed the 1-A current capability of LM3405 and, therefore, R1 minimum must be approximately

0.2 Ω. IFmust also be kept above 200 mA for stable operation, and therefore R1 maximum must be

approximately 1 Ω. If average LED currents less than 200 mA are desired, the EN/DIM pin can be used for PWM

dimming. See LED PWM Dimming.

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Feature Description (continued)

7.3.3 Output Voltage

The output voltage is primarily determined by the number of LEDs (n) connected from VOUT to FB pin and

therefore VOUT can be calculated with Equation 10.

VOUT = ((n × VF)+VFB)

where

• VFis the forward voltage of one LED at the set LED current level (see LED manufacturer data sheet for

forward characteristics curve) (10)

7.3.4 Enable Mode or Shutdown Mode

The LM3405 has both enable and shutdown modes that are controlled by the EN/DIM pin. Connecting a voltage

source greater than 1.8 V to the EN/DIM pin enables the operation of LM3405, while reducing this voltage below

0.4 V places the part in a low quiescent current (0.3 µA typical) shutdown mode. There is no internal pullup on

EN/DIM pin, therefore an external signal is required to initiate switching. Do not allow this pin to float or rise to

0.3 V above VIN. It must be noted that when the EN/DIM pin voltage rises above 1.8 V while the input voltage is

greater than UVLO, there is a finite delay before switching starts. During this delay, the LM3405 goes through a

power on reset state after which the internal soft-start process commences. The soft-start process limits the

inrush current and brings up the LED current (IF) in a smooth and controlled fashion. The total combined duration

of the power on reset delay, soft-start delay and the delay to fully establish the LED current is in the order of

100 µs (see Figure 19).

The simplest way to enable the operation of LM3405 is to connect the EN/DIM pin to VIN which allows self start-

up of LM3405 whenever the input voltage is applied. However, when an input voltage of slow rise time is used to

power the application and if both the input voltage and the output voltage are not fully established before the soft-

start time elapses, the control circuit commands maximum duty cycle operation of the internal power switch to

bring up the output voltage rapidly. When the feedback pin voltage exceeds 0.205 V, the duty cycle has to

reduce from the maximum value accordingly, to maintain regulation. It takes a finite amount of time for this

reduction of duty cycle and this results in a spike in LED current for a short duration as shown in Figure 15. In

applications where this LED current overshoot is undesirable, EN/DIM pin voltage can be separately applied and

delayed such that VIN is fully established before the EN/DIM pin voltage reaches the enable threshold. The effect

of delaying EN/DIM with respect to VIN on the LED current is shown in Figure 16. For a fast rising input voltage

(200 µs for example), there is no need to delay the EN/DIM signal, because soft-start can smoothly bring up the

LED current as shown in Figure 17.

Figure 15. Start-Up Response to VIN With 5-ms Rise Time Figure 16. Start-Up Response to VIN With EN/DIM Delayed

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Feature Description (continued)

Figure 17. Start-Up Response to VIN With 200-µs Rise Time

7.3.5 LED PWM Dimming

The LED brightness can be controlled by applying a periodic pulse signal to the EN/DIM pin and varying its

frequency and/or duty cycle. This so-called PWM dimming method controls the average light output by pulsing

the LED current between the set value and zero. A logic high level at the EN/DIM pin turns on the LED current

whereas a logic low level turns off the LED current. Figure 18 shows a typical LED current waveform in PWM

dimming mode. As explained in the previous section, there is approximately a 100-µs delay from the EN/DIM

signal going high to fully establishing the LED current as shown in Figure 19. This 100-µs delay sets a maximum

frequency limit for the driving signal that can be applied to the EN/DIM pin for PWM dimming. Figure 20 shows

the average LED current versus duty cycle of PWM dimming signal for various frequencies. The applicable

frequency range to drive LM3405 for PWM dimming is from 100 Hz to 5 kHz. The dimming ratio reduces

drastically when the applied PWM dimming frequency is greater than 5 kHz.

Figure 18. PWM Dimming of LEDs

Using the EN/DIM Pin Figure 19. Start-Up Response to EN/DIM

With IF= 1 A

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Feature Description (continued)

Figure 20. Average LED Current vs

Duty Cycle of PWM Dimming Signal at EN/DIM Pin

7.3.6 Undervoltage Lockout

Undervoltage lockout (UVLO) prevents the LM3405 from operating until the input voltage exceeds 2.74 V

(typical). The UVLO threshold has approximately 440 mV of hysteresis, so the part operates until VIN drops

below 2.3 V (typical). Hysteresis prevents the part from turning off during power up if VIN is non-monotonic.

7.3.7 Current Limit

The LM3405 uses cycle-by-cycle current limit to protect the internal power switch. During each switching cycle, a

current limit comparator detects if the power switch current exceeds 2 A (typical), and turns off the switch until

the next switching cycle begins.

7.3.8 Overcurrent Protection

The LM3405 has a built-in overcurrent comparator that compares the FB pin voltage to a threshold voltage that is

60% higher than the internal reference VREF. Once the FB pin voltage exceeds this threshold level (typically

328 mV), the internal NMOS power switch is turned off, which allows the feedback voltage to decrease towards

regulation. This threshold provides an upper limit for the LED current. LED current overshoot is limited to 328

mV/R1 by this comparator during transients.

7.4 Device Functional Modes

7.4.1 Thermal Shutdown

Thermal shutdown limits total power dissipation by turning off the internal power switch when the IC junction

temperature exceeds 165°C. After thermal shutdown occurs, the power switch does not turn on until the junction

temperature drops below approximately 150°C.

L = VOUT + VD1

IF x r x fSW x (1-D)

r = 'iL

D = VOUT + VD1

VIN + VD1 - VSW

D = VOUT

VIN

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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 Inductor (L1)

The duty cycle (D) can be approximated quickly using the ratio of output voltage (VOUT) to input voltage (VIN) in

Equation 11.

(11)

The catch diode (D1) forward voltage drop and the voltage drop across the internal NMOS must be included to

calculate a more accurate duty cycle. Calculate D by using Equation 12.

(12)

VSW can be approximated by Equation 13.

VSW = IF× RDS(ON) (13)

The diode forward drop (VD1) can range from 0.3 V to 0.7 V depending on the quality of the diode. The lower VD1

is, the higher the operating efficiency of the converter.

The inductor value determines the output ripple current (ΔiL, as defined in Figure 11). Lower inductor values

decrease the size of the inductor, but increases the output ripple current. An increase in the inductor value

decreases the output ripple current. The ratio of ripple current to LED current is optimized when it is set between

0.3 and 0.4 at 1A LED current. This ratio r is defined as:

(14)

One must also ensure that the minimum current limit (1.2 A) is not exceeded, so the peak current in the inductor

must be calculated. The peak current (ILPK) in the inductor is calculated with Equation 15.

ILPK = IF+ΔiL/2 (15)

When the designed maximum output current is reduced, the ratio (r) can be increased. At a current of 0.2 A,

r can be made as high as 0.7. The ripple ratio can be increased at lighter loads because the net ripple is actually

quite low, and if r remains constant the inductor value can be made quite large. An equation empirically

developed for the maximum ripple ratio at any current below 2 A is calculated with Equation 16 (note that this is

just a guideline).

r = 0.387 × IOUT–0.3667 (16)

The LM3405 operates at a high frequency allowing the use of ceramic output capacitors without compromising

transient response. Ceramic capacitors allow higher inductor ripple without significantly increasing LED current

ripple. See the output capacitor and feed-forward capacitor sections for more details on LED current ripple.

Now that the ripple current or ripple ratio is determined, the inductance is calculated by Equation 17.

where

• fSW is the switching frequency

• IFis the LED current (17)

IRMS-IN = IF x D x r2

1 - D +

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Application Information (continued)

When selecting an inductor, make sure that it is capable of supporting the peak output current without saturating.

Inductor saturation results in a sudden reduction in inductance and prevent the regulator from operating correctly.

Because of the operating frequency of the LM3405, 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 selection, see Circuit

Examples and Recommended Inductance Range in Table 1.

(1) Maximum over full range of VIN and VOUT.

(2) Small inductance improves stability without causing a significant increase in LED current ripple.

Table 1. Recommended Inductance Range

IFINDUCTANCE RANGE AND INDUCTOR CURRENT RIPPLE

1 A

4.7 µH TO 10 µH

Inductance 4.7 µH 6.8 µH 10 µH

ΔiL/ IF(1) 51% 35% 24%

0.6 A

6.8 µH TO 15 µH

Inductance 6.8 µH 10 µH 15 µH

ΔiL/ IF(1) 58% 40% 26%

0.2 A

4.7 µH(2) TO 22 µH

Inductance 10 µH 15 µH 22 µH

ΔiL/ IF(1) 119% 79% 54%

8.1.2 Input Capacitor (C1)

An input capacitor is necessary to ensure that VIN does not drop excessively during switching transients. The

primary specifications of the input capacitor are capacitance, voltage rating, RMS current rating, and ESL

(Equivalent Series Inductance). The input voltage rating is specifically stated by the capacitor manufacturer.

Check any recommended deratings and also verify if there is any significant change in capacitance at the

operating input voltage and the operating temperature. The input capacitor maximum RMS input current rating

(IRMS-IN) must be greater than Equation 18.

(18)

Equation 18 shows that maximum RMS capacitor current occurs when D = 0.5. Always calculate the RMS at the

point where the duty cycle D, is closest to 0.5. The ESL of an input capacitor is usually determined by the

effective cross sectional area of the current path. A large-leaded capacitor has high ESL and an 0805 ceramic

chip capacitor has very low ESL. At the operating frequency of the LM3405, certain capacitors may have an ESL

so large that the resulting inductive impedance (2 πfL) is higher than that required to provide stable operation. TI

strongly recommends using ceramic capacitors due to their low ESR and low ESL. A 10-µF multilayer ceramic

capacitor (MLCC) is a good choice for most applications. In cases where large capacitance is required, use

surface mount capacitors such as Tantalum capacitors and place at least a 1-µF ceramic capacitor close to the

VIN pin. For MLCCs, TI recommends using X7R or X5R dielectrics. Consult capacitor manufacturer datasheet to

see how rated capacitance varies over operating conditions.

8.1.3 Output Capacitor (C2)

The output capacitor is selected based upon the desired reduction in LED current ripple. A 1-µF ceramic

capacitor results in very low LED current ripple for most applications. Due to the high switching frequency, the

1-µF capacitor alone (without feed-forward capacitor C4) can filter more than 90% of the inductor current ripple

for most applications where the sum of LED dynamic resistance and R1 is larger than 1 Ω. Because the internal

compensation is tailored for small output capacitance with very low ESR, TI strongly recommends using a

ceramic capacitor with capacitance less than 3.3 µF.

IRMS-OUT = IF x r

LM3405

www.ti.com

SNVS429C –OCTOBER 2006–REVISED DECEMBER 2016

Product Folder Links: LM3405

Given the availability and quality of MLCCs and the expected output voltage of designs using the LM3405, there

is really no need to review other capacitor technologies. A benefit of ceramic capacitors is their ability to bypass

high frequency noise. A certain amount of switching edge noise couples through the parasitic capacitances in the

inductor to the output. A ceramic capacitor bypasses this noise. In cases where large capacitance is required,

use Electrolytic or Tantalum capacitors with large ESR, and verify the loop performance on the bench. Like the

input capacitor, multilayer ceramic capacitors are recommended X7R or X5R. Again, verify actual capacitance at

the desired operating voltage and temperature.

Check the RMS current rating of the capacitor. The maximum RMS current rating of the capacitor is calculated

with Equation 19.

(19)

One may select a 1206 size ceramic capacitor for C2, because its current rating is typically higher than 1 A,

more than enough for the requirement.

8.1.4 Feed-Forward Capacitor (C4)

The feed-forward capacitor (designated as C4) connected in parallel with the LED string is required to provide

multiple benefits to the LED driver design. It greatly improves the large signal transient response and suppresses

LED current overshoot that may otherwise occur during PWM dimming; it also helps to shape the rise and fall

times of the LED current pulse during PWM dimming thus reducing EMI emission; it reduces LED current ripple

by bypassing some of inductor ripple from flowing through the LED. For most applications, a 1-µF ceramic

capacitor is sufficient. In fact, the combination of a 1-µF feed-forward ceramic capacitor and a 1-µF output

ceramic capacitor leads to less than 1% current ripple flowing through the LED. Lower and higher C4 values can

be used, but bench validation is required to ensure the performance meets the application requirement.

Figure 21 shows a typical LED current waveform during PWM dimming without feed-forward capacitor. At the

beginning of each PWM cycle, overshoot can be seen in the LED current. Adding a 1-µF feed-forward capacitor

can totally remove the overshoot as shown in Figure 22.

Figure 21. PWM Dimming Without Feed-Forward Capacitor Figure 22. PWM Dimming With a 1-µF Feed-Forward

Capacitor

8.1.5 Catch Diode (D1)

The catch diode (D1) conducts during the switch off-time. A Schottky diode is required for its fast switching time

and low forward voltage drop. The catch diode must be chosen such that its current rating is greater than

Equation 20.

ID1 = IF× (1-D) (20)

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

To improve efficiency, choose a Schottky diode with a low forward voltage drop.

 

COND F DS(ON)

P I D 1 R

3 I

§ ·

¨ ¸

u u  u u

¨ ¸

LM3405

SNVS429C –OCTOBER 2006–REVISED DECEMBER 2016

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Product Folder Links: LM3405

8.1.6 Boost Diode (D2)

TI recommends a standard diode such as the 1N4148 type. For VBOOST circuits derived from voltages less than

3.3 V, a small-signal Schottky diode is recommended for better efficiency. A good choice is the BAT54 small

signal diode.

8.1.7 Boost Capacitor (C3)

A 0.01-µF ceramic capacitor with a voltage rating of at least 6.3 V is sufficient. The X7R and X5R MLCCs

provide the best performance.

8.1.8 Power Loss Estimation

The main power loss in LM3405 includes three basic types of loss in the internal power switch: conduction loss,

switching loss, and gate charge loss. In addition, there is loss associated with the power required for the internal

circuitry of IC.

The conduction loss is calculated with Equation 21.

(21)

If the inductor ripple current is fairly small (for example, less than 40%), the conduction loss can be simplified

with Equation 22.

PCOND = IF2× RDS(ON) × D (22)

The switching loss occurs during the switch on and off transition periods, where voltage and current overlap

resulting in power loss. The simplest means to determine this loss is to empirically measure the rise and fall

times (10% to 90%) of the voltage at the switch pin.

Switching power loss is calculated with Equation 23.

PSW = 0.5 × VIN × IF× fSW × ( TRISE + TFALL ) (23)

The gate charge loss is associated with the gate charge QGrequired to drive the switch with Equation 24.

PG= fSW × VIN × QG(24)

The power loss required for operation of the internal circuitry is calculated with Equation 25.

PQ= IQ× VIN (25)

IQis the quiescent operating current, and is typically around 1.8mA for the LM3405.

The total power loss in the IC is Equation 26.

PINTERNAL = PCOND + PSW + PG+ PQ(26)

An example of power losses for a typical application is shown in Table 2,Equation 27, and Equation 28 (D is

calculated to be 0.36).

Table 2. Power Loss Tabulation

CONDITIONS POWER LOSS

VIN 12 V — —

VOUT 3.9 V — —

IOUT 1 A — —

VD1 0.45 V — —

RDS(ON) 300 mΩPCOND 111 mW

fSW 1.6 MHz — —

TRISE 18 ns PSW 288 mW

TFALL 12 ns

IQ1.8 mA PQ22 mW

QG1.4 nC PG27 mW

D = VOUT

VIN = 3.6V

5V = 0.72

LM3405

VIN VIN

EN/DIM

BOOST

GND

DC or

PWM

LED1

VOUT

LM3405

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SNVS429C –OCTOBER 2006–REVISED DECEMBER 2016

Product Folder Links: LM3405

Σ( PCOND + PSW + PQ+ PG)=PINTERNAL (27)

PINTERNAL = 448 mW (28)

8.2 Typical Applications

8.2.1 VBOOST Derived from VIN (VIN =5V,IF= 1 A)

Figure 23. VBOOST Derived from VIN

(VIN =5V,IF= 1 A) Diagram

8.2.1.1 Design Requirements

The following are the parameter specifications for this design example:

• Input voltage, VIN = 5 V ± 10%

• LED current, IF=1A

• LED forward voltage, VLED = 3.4 V

• Output voltage, VOUT =3.4V+0.2V=3.6V

• Ripple ratio = r < 0.6

• PWM dimmable

8.2.1.2 Detailed Design Procedure

8.2.1.2.1 Calculate Duty Cycle (D)

Calculate the nominal duty cycle for calculations and ensure the maximum duty cycle is not exceeded in the

application using Equation 29.

(29)

Using the same equation DMAX can be calculated for the minimum input voltage of 4.5 V. The duty cycle at 4.5 V

is 0.8 which is less than the minimum DMAX of 0.85 specified in Electrical Characteristics.

8.2.1.2.2 Choose Capacitor Values (C1, C2, C3, and C4)

Low input voltage applications and PWM dimming applications generally require more input capacitance so the

higher value of C1 = 10 µF is chosen for best performance. The other capacitor values chosen are the

recommended values of C2 = C4 = 1 µF and C3 = 0.01 µF. All capacitors chosen are X5R or X7R dielectric

ceramic capacitors of sufficient voltage rating.

L = VOUT + VD1

IF × r × fSW = 3.6V + 0.37V

1A × 0.6 × 1.6MHz = 4.1H

ID1 = IF × :1 - D; = 1A × :1 - 0.72; = 0.28A

R1 = VFB

IF = 0.205V

1A = 0.205

LM3405

SNVS429C –OCTOBER 2006–REVISED DECEMBER 2016

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Product Folder Links: LM3405

Typical Applications (continued)

8.2.1.2.3 Set the Nominal LED Current (R1)

The nominal LED current at 100% PWM dimming duty cycle is set by the resistor R1. R1 can be calculated using

Equation 30.

(30)

The standard value of R1 = 0.2 Ωis chosen. R1 must have a power rating of at least 1/4 W.

8.2.1.2.4 Choose Diodes (D1 and D2)

For the boost diode, D2, choose a low current diode with a voltage rating greater than the input voltage to give

some margin. D2 must also be a schottky to minimize the forward voltage drop. For this example a schottky

diode of D2 = 100 mA, 30 V is chosen. The catch diode, D1, must be a schottky diode and must have a voltage

rating greater than the input voltage and a current rating greater than the average current. The average current in

D1 can be calculated with Equation 31.

(31)

For this example D1 = 1 A, 10 V is chosen.

8.2.1.2.5 Calculate the Inductor Value (L1)

The inductor value is chosen for a given ripple ratio (r). To calculate L1 the forward voltage of D1 is required. In

this case the chosen diode has a forward voltage drop of VF= 0.37 V. Given the desired ripple ratio L1 is

calculated with Equation 32.

(32)

The next larger standard value of L1 = 4.7 µH is chosen. A ripple ratio of 0.6 translates to a ΔiLof 600 mA and a

peak inductor current of 1.3 A (IF+ΔiL/2). Choose an inductor with a saturation current rating of greater than

1.3 A.

Table 3. Bill of Materials for Figure 23

PART ID PART VALUE PART NUMBER MANUFACTURER

U1 1-A LED Driver LM3405 Texas Instruments

C1, Input capacitor 10 µF, 6.3 V, X5R C3216X5R0J106M TDK

C2, Output capacitor 1 µF, 10 V, X7R GRM319R71A105KC01D Murata

C3, Boost capacitor 0.01 µF, 16 V, X7R 0805YC103KAT2A AVX

C4, Feedforward capacitor 1 µF, 10 V, X7R GRM319R71A105KC01D Murata

D1, Catch diode Schottky, 0.37 V at 1A, VR= 10 V MBRM110LT1G ON Semiconductor

D2, Boost diode Schottky, 0.36 V at 15 mA CMDSH-3 Central Semiconductor

L1 4.7 µH, 1.6 A SLF6028T-4R7M1R6 TDK

R1 0.2 Ω, 0.5 W, 1% WSL2010R2000FEA Vishay

LM3405

VIN

EN/DIM

BOOST

GND

VIN

DC or

PWM

LED1

VOUT

LM3405

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SNVS429C –OCTOBER 2006–REVISED DECEMBER 2016

Product Folder Links: LM3405

8.2.1.3 Application Curve

Figure 24. Efficiency vs Input Voltage

8.3 System Examples

8.3.1 VBOOST Derived From VOUT (VIN = 12 V, IF= 1 A)

Figure 25. VBOOST Derived From VOUT

(VIN = 12 V, IF= 1 A) Diagram

8.3.1.1 Bill of Materials

Table 4. Bill of Materials for Figure 25

PART ID PART VALUE PART NUMBER MANUFACTURER

U1 1-A LED Driver LM3405 Texas Instruments

C1, Input capacitor 10 µF, 25 V, X5R ECJ-3YB1E106K Panasonic

C2, Output capacitor 1 µF, 10 V, X7R GRM319R71A105KC01D Murata

C3, Boost capacitor 0.01 µF, 16 V, X7R 0805YC103KAT2A AVX

C4, Feedforward capacitor 1 µF, 10 V, X7R GRM319R71A105KC01D Murata

D1, Catch diode Schottky, 0.5 V at 1 A, VR= 30 V SS13 Vishay

D2, Boost diode Schottky, 0.36 V at 15 mA CMDSH-3 Central Semiconductor

L1 4.7 µH, 1.6 A SLF6028T-4R7M1R6 TDK

R1 0.2 Ω, 0.5 W, 1% WSL2010R2000FEA Vishay

LM3405

VIN VIN

EN/DIM

BOOST

GND

DC or

PWM

LED1

VOUT

LM3405

VIN VIN

EN/DIM

BOOST

GND

D2D3

DC or

PWM

LED1

VOUT

LM3405

SNVS429C –OCTOBER 2006–REVISED DECEMBER 2016

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Product Folder Links: LM3405

8.3.2 VBOOST Derived From VIN Through a Series Zener Diode, D3 (VIN = 15 V, IF= 1 A)

Figure 26. VBOOST Derived From VIN Through a Series Zener Diode, D3

(VIN = 15 V, IF= 1 A) Diagram

8.3.2.1 Bill of Materials

Table 5. Bill of Materials for Figure 26

PART ID PART VALUE PART NUMBER MANUFACTURER

U1 1-A LED Driver LM3405 Texas Instruments

C1, Input capacitor 10 µF, 25 V, X5R ECJ-3YB1E106K Panasonic

C2, Output capacitor 1 µF, 10 V, X7R GRM319R71A105KC01D Murata

C3, Boost capacitor 0.01 µF, 16 V, X7R 0805YC103KAT2A AVX

C4, Feedforward capacitor 1 µF, 10 V, X7R GRM319R71A105KC01D Murata

D1, Catch diode Schottky, 0.5 V at 1A, VR= 30 V SS13 Vishay

D2, Boost diode Schottky, 0.36 V at 15 mA CMDSH-3 Central Semiconductor

D3, Zener diode 11 V, 350 mW, SOT-23 BZX84C11 Fairchild

L1 6.8 µH, 1.5 A SLF6028T-6R8M1R5 TDK

R1 0.2 Ω, 0.5 W, 1% WSL2010R2000FEA Vishay

8.3.3 VBOOST Derived From VIN Through a Shunt Zener Diode, D3 (VIN = 15 V, IF= 1 A)

Figure 27. VBOOST Derived From VIN Through a Shunt Zener Diode, D3

(VIN = 15 V, IF= 1 A) Diagram

LM3405

VIN VIN

EN/DIM

BOOST

GND

D2D3

DC or

PWM

LED1

VOUT

LM3405

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SNVS429C –OCTOBER 2006–REVISED DECEMBER 2016

Product Folder Links: LM3405

8.3.3.1 Bill of Materials

Table 6. Bill of Materials for Figure 27

PART ID PART VALUE PART NUMBER MANUFACTURER

U1 1-A LED Driver LM3405 Texas Instruments

C1, Input capacitor 10 µF, 25 V, X5R ECJ-3YB1E106K Panasonic

C2, Output capacitor 1 µF, 10 V, X7R GRM319R71A105KC01D Murata

C3, Boost capacitor 0.01 µF, 16 V, X7R 0805YC103KAT2A AVX

C4, Feedforward capacitor 1 µF, 10 V, X7R GRM319R71A105KC01D Murata

C5, Shunt capacitor 0.1 µF, 16 V, X7R GRM219R71C104KA01D Murata

D1, Catch diode Schottky, 0.5 V at 1 A, VR= 30 V SS13 Vishay

D2, Boost diode Schottky, 0.36 V at 15 mA CMDSH-3 Central Semiconductor

D3, Zener diode 4.7 V, 350 mW, SOT-23 BZX84C4 V7 Fairchild

L1 6.8 µH, 1.5 A SLF6028T-6R8M1R5 TDK

R1 0.2 Ω, 0.5 W, 1% WSL2010R2000FEA Vishay

R2 1.91 kΩ, 1% CRCW08051K91FKEA Vishay

8.3.4 VBOOST Derived from VOUT Through a Series Zener Diode, D3 (VIN = 15 V, IF= 1 A)

Figure 28. VBOOST Derived from VOUT Through a Series Zener Diode, D3

(VIN = 15 V, IF= 1 A) Diagram

8.3.4.1 Bill of Materials

Table 7. Bill of Materials for Figure 28

PART ID PART VALUE PART NUMBER MANUFACTURER

U1 1-A LED Driver LM3405 Texas Instruments

C1, Input capacitor 10 µF, 25 V, X5R ECJ-3YB1E106K Panasonic

C2, Output capacitor 1 µF, 16 V, X7R GRM319R71A105KC01D Murata

C3, Boost capacitor 0.01 µF, 16 V, X7R 0805YC103KAT2A AVX

C4, Feedforward capacitor 1 µF, 16 V, X7R GRM319R71A105KC01D Murata

D1, Catch diode Schottky, 0.5 V at 1 A, VR= 30 V SS13 Vishay

D2, Boost diode Schottky, 0.36 V at 15 mA CMDSH-3 Central Semiconductor

D3, Zener diode 11 V, 350 mW, SOT-23 BZX84C11 Fairchild

L1 6.8 µH, 1.5 A SLF6028T-6R8M1R5 TDK

R1 0.2 Ω, 0.5 W, 1% WSL2010R2000FEA Vishay

GND

LED+

LED-

BOOST SW

GND VIN

FB EN/DIM

VIA (GND VIAS TIED TO BOTTOM LAYER GROUND PLANE)

VIN

GND

LM3405

SNVS429C –OCTOBER 2006–REVISED DECEMBER 2016

www.ti.com

Product Folder Links: LM3405

9 Power Supply Recommendations

Any DC output power supply may be used provided it has a high enough voltage and current rating required for

the particular application.

10 Layout

10.1 Layout Guidelines

When planning the layout there are a few things to consider when trying to achieve a clean, regulated output.

The most important consideration when completing the layout is the close coupling of the GND connections of

the input capacitor C1 and the catch diode D1. These ground ends must be close to one another and be

connected to the GND plane with at least two vias. Place these components as close to the IC as possible. The

next consideration is the location of the GND connection of the output capacitor C2, which must be near the

GND connections of C1 and D1.

There must be a continuous ground plane on the bottom layer of a two-layer board.

The FB pin is a high impedance node and take care to make the FB trace short to avoid noise pickup that

causes inaccurate regulation. The LED current setting resistor R1 must be placed as close as possible to the IC,

with the GND of R1 placed as close as possible to the GND of the IC. The VOUT trace to LED anode must be

routed away from the inductor and any other traces that are switching.

High AC currents flow through the VIN, SW and VOUT traces, so they must be as short and wide as possible.

Radiated noise can be decreased by choosing a shielded inductor.

The remaining components must also be placed as close as possible to the IC. See AN-1229 SIMPLE

SWITCHER®PCB Layout Guidelines (SNVA054) for further considerations.

10.2 Layout Example

Schematic in Figure 23

Figure 29. LM3405 Layout Example

LM3405

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SNVS429C –OCTOBER 2006–REVISED DECEMBER 2016

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11 Device and Documentation Support

11.1 Documentation Support

11.1.1 Related Documentation

For related documentation see the following:

•AN-1229 SIMPLE SWITCHER® PCB Layout Guidelines (SNVA054)

•AN-1644 Powering and Dimming High-Brightness LEDs with the LM3405 Constant-Current Buck Regulator

(SNVA247)

•AN-1656 Design Challenges of Switching LED Drivers (SNVA253)

•AN-1685 LM3405A Demo Board (SNVA271)

•AN-1899 LM3405A VSSOP Evaluation Board (SNVA370)

•AN-1982 Small, Wide Input Voltage Range LM2842 Keeps LEDs Cool (SNVA402)

•LM3405A Reference Design for MR16 LED Bulb, 600mA (SNVU101)

11.2 Receiving Notification of Documentation Updates

To receive notification of documentation updates, navigate to the device product folder on ti.com. In the upper

right corner, click on Alert me to register and receive a weekly digest of any product information that has

changed. For change details, review the revision history included in any revised document.

11.3 Community Resource

The following links connect to TI community resources. Linked contents are provided "AS IS" by the respective

contributors. They do not constitute TI specifications and do not necessarily reflect TI's views; see TI's Terms of

Use.

TI E2E™ Online Community TI's Engineer-to-Engineer (E2E) Community. Created to foster collaboration

among engineers. At e2e.ti.com, you can ask questions, share knowledge, explore ideas and help

solve problems with fellow engineers.

Design Support TI's Design Support Quickly find helpful E2E forums along with design support tools and

contact information for technical support.

11.4 Trademarks

E2E is a trademark of Texas Instruments.

SIMPLE SWITCHER is a registered trademark of Texas Instruments.

All other trademarks are the property of their respective owners.

11.5 Electrostatic Discharge Caution

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.

11.6 Glossary

SLYZ022 —TI Glossary.

This glossary lists and explains terms, acronyms, and definitions.

12 Mechanical, Packaging, and Orderable Information

The following pages include mechanical, packaging, and orderable information. This information is the most

current data available for the designated devices. This data is subject to change without notice and revision of

this document. For browser-based versions of this data sheet, refer to the left-hand navigation.

PACKAGE OPTION ADDENDUM

www.ti.com 6-Feb-2020

Addendum-Page 1

PACKAGING INFORMATION

Orderable Device Status

(1)

Package Type Package

Drawing Pins Package

Qty Eco Plan

(2)

Lead/Ball Finish

(6)

MSL Peak Temp

(3)

Op Temp (°C) Device Marking

(4/5)

Samples

LM3405XMK/NOPB ACTIVE SOT-23-THIN DDC 6 1000 Green (RoHS

& no Sb/Br) SN Level-1-260C-UNLIM -40 to 125 SPNB

LM3405XMKX/NOPB ACTIVE SOT-23-THIN DDC 6 3000 Green (RoHS

& no Sb/Br) SN Level-1-260C-UNLIM -40 to 125 SPNB

(1) The marketing status values are defined as follows:

ACTIVE: Product device recommended for new designs.

LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect.

NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design.

PREVIEW: Device has been announced but is not in production. Samples may or may not be available.

OBSOLETE: TI has discontinued the production of the device.

(2) RoHS: TI defines "RoHS" to mean semiconductor products that are compliant with the current EU RoHS requirements for all 10 RoHS substances, including the requirement that RoHS substance

do not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, "RoHS" products are suitable for use in specified lead-free processes. TI may

reference these types of products as "Pb-Free".

RoHS Exempt: TI defines "RoHS Exempt" to mean products that contain lead but are compliant with EU RoHS pursuant to a specific EU RoHS exemption.

Green: TI defines "Green" to mean the content of Chlorine (Cl) and Bromine (Br) based flame retardants meet JS709B low halogen requirements of <=1000ppm threshold. Antimony trioxide based

flame retardants must also meet the <=1000ppm threshold requirement.

(3) MSL, Peak Temp. - The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature.

(4) There may be additional marking, which relates to the logo, the lot trace code information, or the environmental category on the device.

(5) Multiple Device Markings will be inside parentheses. Only one Device Marking contained in parentheses and separated by a "~" will appear on a device. If a line is indented then it is a continuation

of the previous line and the two combined represent the entire Device Marking for that device.

(6) Lead/Ball Finish - Orderable Devices may have multiple material finish options. Finish options are separated by a vertical ruled line. Lead/Ball Finish values may wrap to two lines if the finish

value exceeds the maximum column width.

Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided. TI bases its knowledge and belief on information

provided by third parties, and makes no representation or warranty as to the accuracy of such information. Efforts are underway to better integrate information from third parties. TI has taken and

continues to take reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on incoming materials and chemicals.

TI and TI suppliers consider certain information to be proprietary, and thus CAS numbers and other limited information may not be available for release.

In no event shall TI's liability arising out of such information exceed the total purchase price of the TI part(s) at issue in this document sold by TI to Customer on an annual basis.

PACKAGE OPTION ADDENDUM

www.ti.com 6-Feb-2020

Addendum-Page 2

TAPE AND REEL INFORMATION

*All dimensions are nominal

Device Package

Type Package

Drawing Pins SPQ Reel

Diameter

(mm)

Reel

Width

W1 (mm)

(mm) B0

(mm) K0

(mm) P1

(mm) W

(mm) Pin1

Quadrant

LM3405XMK/NOPB SOT-

23-THIN DDC 6 1000 178.0 8.4 3.2 3.2 1.4 4.0 8.0 Q3

LM3405XMKX/NOPB SOT-

23-THIN DDC 6 3000 178.0 8.4 3.2 3.2 1.4 4.0 8.0 Q3

PACKAGE MATERIALS INFORMATION

www.ti.com 29-Mar-2017

Pack Materials-Page 1

*All dimensions are nominal

Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm)

LM3405XMK/NOPB SOT-23-THIN DDC 6 1000 210.0 185.0 35.0

LM3405XMKX/NOPB SOT-23-THIN DDC 6 3000 210.0 185.0 35.0

PACKAGE MATERIALS INFORMATION

www.ti.com 29-Mar-2017

Pack Materials-Page 2

www.ti.com

PACKAGE OUTLINE

0.20

0.12 TYP 0.25

3.05

2.55

4X 0.95

1.100

0.847

0.1

0.0 TYP

6X 0.5

0.3

0.6

0.3 TYP

1.9

0 -8 TYP

3.05

2.75

1.75

1.45

SOT - 1.1 max heightDDC0006A

SOT

4214841/B 11/2020

NOTES:

1. All linear dimensions are in millimeters. Any dimensions in parenthesis are for reference only. Dimensioning and tolerancing

per ASME Y14.5M.

2. This drawing is subject to change without notice.

3. Reference JEDEC MO-193.

0.2 C A B

INDEX AREA

PIN 1

GAGE PLANE

SEATING PLANE

0.1 C

SCALE 4.000

www.ti.com

EXAMPLE BOARD LAYOUT

0.07 MAX

ARROUND 0.07 MIN

ARROUND

6X (1.1)

6X (0.6)

(2.7)

4X (0.95)

(R0.05) TYP

4214841/B 11/2020

SOT - 1.1 max heightDDC0006A

SOT

NOTES: (continued)

4. Publication IPC-7351 may have alternate designs.

5. Solder mask tolerances between and around signal pads can vary based on board fabrication site.

SYMM

LAND PATTERN EXAMPLE

EXPLOSED METAL SHOWN

SCALE:15X

SYMM

SOLDER MASK

OPENING

METAL UNDER

SOLDER MASK

DEFINED

EXPOSED METAL

METAL

SOLDER MASK

OPENING

NON SOLDER MASK

DEFINED

SOLDERMASK DETAILS

EXPOSED METAL

www.ti.com

EXAMPLE STENCIL DESIGN

(2.7)

4X(0.95)

6X (1.1)

6X (0.6)

(R0.05) TYP

SOT - 1.1 max heightDDC0006A

SOT

4214841/B 11/2020

NOTES: (continued)

6. Laser cutting apertures with trapezoidal walls and rounded corners may offer better paste release. IPC-7525 may have alternate

design recommendations.

7. Board assembly site may have different recommendations for stencil design.

SOLDER PASTE EXAMPLE

BASED ON 0.125 THICK STENCIL

SCALE:15X

SYMM

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