LM3444MAX/NOPB - NATIONAL SEMICONDUCTOR

LM3444

LM3444 AC-DC Offline LED Driver

Literature Number: SNVS682B

LM3444

November 17, 2011

AC-DC Offline LED Driver

General Description

The LM3444 is an adaptive constant off-time AC/DC buck

(step-down) constant current controller that provides a con-

stant current for illuminating high power LEDs. The high fre-

quency capable architecture allows the use of small external

passive components. A passive PFC circuit ensures good

power factor by drawing current directly from the line for most

of the cycle, and provides a constant positive voltage to the

buck regulator. Additional features include thermal shutdown,

current limit and VCC under-voltage lockout. The LM3444 is

available in a low profile MSOP-10 package or an 8 lead SOIC

package.

Features

■Application voltage range 80VAC – 277VAC

■Capable of controlling LED currents greater than 1A

■Adjustable switching frequency

■Low quiescent current

■Adaptive programmable off-time allows for constant ripple

current

■Thermal shutdown

■No 120Hz flicker

■Low profile 10 pin MSOP package or 8 lead SOIC package

■Patent pending drive architecture

Applications

■Solid State Lighting

■Industrial and Commercial Lighting

■Residential Lighting

Typical LM3444 LED Driver Application Circuit

30127501

30127505

LM3444 AC-DC Offline LED Driver

Connection Diagrams

Top View

30127573

10-Pin MSOP

NS Package Number MUB10A

Top View

30127503

8-Pin SOIC

NS Package Number M08A

Ordering Information

Order Number Spec. Package Type NSC Package

Drawing Top Mark Supplied As

LM3444MM NOPB MSOP-10 MUB10A SZTB 1000 Units, Tape and Reel

LM3444MMX NOPB MSOP-10 MUB10A SZTB 3500 Units, Tape and Reel

LM3444MA NOPB SOIC-8 M08A LM3444MA 95 Units, Rail

LM3444MAX NOPB SOIC-8 M08A LM3444MA 2500 Units, Tape and Reel

Pin Descriptions

MSOP SOIC Name Description

1 1 NC No internal connection. Leave this pin open.

2 NC No internal connection. Leave this pin open.

3 NC No internal connection. Leave this pin open.

4 8 COFF OFF time setting pin. A user set current and capacitor connected from the output to this pin sets

the constant OFF time of the switching controller.

5 2 FILTER Filter input. A low pass filter tied to this pin can filter a PWM dimming signal to supply a DC

voltage to control the LED current. Can also be used as an analog dimming input. If not used for

dimming connect a 0.1µF capacitor from this pin to ground.

6 3 GND Circuit ground connection.

7 4 ISNS LED current sense pin. Connect a resistor from main switching MOSFET source, ISNS to GND

to set the maximum LED current.

8 5 GATE Power MOSFET driver pin. This output provides the gate drive for the power switching MOSFET

of the buck controller.

9 6 VCC Input voltage pin. This pin provides the power for the internal control circuitry and gate driver.

10 7 NC No internal connection. Leave this pin open.

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LM3444

Absolute Maximum Ratings (Note 1)

If Military/Aerospace specified devices are required,

please contact the Texas Instruments Sales Office/

Distributors for availability and specifications.

VCC and GATE to GND -0.3V to +14V

ISNS to GND -0.3V to +2.5V

FILTER and COFF to GND -0.3V to +7.0V

COFF Input Current 60mA

Continuous Power Dissipation

(Note 2)

Internally Limited

ESD Susceptibility

HBM (Note 3) 2 kV

Junction Temperature (TJ-MAX) 150°C

Storage Temperature Range -65°C to +150°C

Maximum Lead Temp.

Range (Soldering) 260°C

Operating Conditions

VCC 8.0V to 13V

Junction Temperature −40°C to +125°C

Electrical Characteristics Limits in standard type face are for TJ = 25°C and those with boldface type apply

over the full Operating Temperature Range ( TJ = −40°C to +125°C). Minimum and Maximum limits are guaranteed through test,

design, or statistical correlation. Typical values represent the most likely parametric norm at TJ = +25ºC, and are provided for

reference purposes only. Unless otherwise stated the following conditions apply: VCC = 12V.

Symbol Parameter Conditions Min Typ Max Units

VCC SUPPLY

IVCC Operating supply current 1.58 2.25 mA

VCC-UVLO Rising threshold 7.4 7.7 V

Falling threshold 6.0 6.4

Hysterisis 1

COFF

VCOFF Time out threshold 1.225 1.276 1.327 V

RCOFF Off timer sinking impedance 33 60 Ω

tCOFF Restart timer 180 µs

CURRENT LIMIT

VISNS ISNS limit threshold 1.174 1.269 1.364 V

tISNS Leading edge blanking time 125 ns

Current limit reset delay 180 µs

ISNS limit to GATE delay ISNS = 0 to 1.75V step 33 ns

CURRENT SENSE COMPARATOR

VFILTER FILTER open circuit voltage 720 750 780 mV

RFILTER FILTER impedance 1.12 MΩ

VOS Current sense comparator offset voltage -4.0 0.1 4.0 mV

GATE DRIVE OUTPUT

VDRVH GATE high saturation IGATE = 50 mA 0.24 0.50 V

VDRVL GATE low saturation IGATE = 100 mA 0.22 0.50

IDRV Peak souce current GATE = VCC/2 -0.77 A

Peak sink current GATE = VCC/2 0.88

tDV Rise time Cload = 1 nF 15 ns

Fall time Cload = 1 nF 15

THERMAL SHUTDOWN

TSD Thermal shutdown temperature (Note 4) 165 °C

Thermal shutdown hysteresis 20

THERMAL SPECIFICATION

RθJA MSOP-10 junction to ambient 124 °C/W

RθJC MSOP-10 junction to case 76

Note 1: Absolute maximum ratings are limits beyond which damage to the device may occur. Operating Ratings are conditions for which the device is intended

to be functional, but device parameter specifications may not be guaranteed. For guaranteed specifications and test conditions, see the Electrical Characteristics.

All voltages are with respect to the potential at the GND pin, unless otherwise specified.

Note 2: Internal thermal shutdown circuitry protects the device from permanent damage. Thermal shutdown engages at TJ = 165°C (typ.) and disengages at TJ

= 145°C (typ).

Note 3: Human Body Model, applicable std. JESD22-A114-C.

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LM3444

Note 4: Junction-to-ambient thermal resistance is highly application and board-layout dependent. In applications where high maximum power dissipation exists,

special care must be paid to thermal dissipation issues in board design. In applications where high power dissipation and/or poor package thermal resistance is

present, the maximum ambient temperature may have to be derated. Maximum ambient temperature (TA-MAX) is dependent on the maximum operating junction

temperature (TJ-MAX-OP = 125°C), the maximum power dissipation of the device in the application (PD-MAX), and the junction-to ambient thermal resistance of the

part/package in the application (RθJA), as given by the following equation: TA-MAX = TJ-MAX-OP – (RθJA × PD-MAX).

Typical Performance Characteristics

fSW vs Input Line Voltage

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Efficiency vs Input Line Voltage

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VCC UVLO vs Temperature

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Min On-Time (tON) vs Temperature

30127508

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LM3444

Off Threshold (C11) vs Temperature

-50 -30 -10 10 30 50 70 90 110130150

1.25

1.26

1.27

1.28

1.29

VOFF (V)

TEMPERATURE (°C)

OFF Threshold at C11

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Normalized Variation in fSW over VBUCK Voltage

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Leading Edge Blanking Variation Over Temperature

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LM3444

Simplified Internal Block Diagram

30127511

FIGURE 1. Simplified Block Diagram

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LM3444

Application Information

FUNCTIONAL DESCRIPTION

The LM3444 contains all the necessary circuitry to build a line-

powered (mains powered) constant current LED driver.

Theory of Operation

Refer to Figure 2 below which shows the LM3444 along with

basic external circuitry.

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FIGURE 2. LM3444 Schematic

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LM3444

VALLEY-FILL CIRCUIT

VBUCK supplies the power which drives the LED string. Diode

D3 allows VBUCK to remain high while V+ cycles on and off.

VBUCK has a relatively small hold capacitor C10 which reduces

the voltage ripple when the valley fill capacitors are being

charged. However, the network of diodes and capacitors

shown between D3 and C10 make up a "valley-fill" circuit. The

valley-fill circuit can be configured with two or three stages.

The most common configuration is two stages. Figure 3 illus-

trates a two and three stage valley-fill circuit.

30127518

FIGURE 3. Two and Three Stage Valley Fill Circuit

The valley-fill circuit allows the buck regulator to draw power

throughout a larger portion of the AC line. This allows the ca-

pacitance needed at VBUCK to be lower than if there were no

valley-fill circuit, and adds passive power factor correction

(PFC) to the application.

VALLEY-FILL OPERATION

When the “input line is high”, power is derived directly through

D3. The term “input line is high” can be explained as follows.

The valley-fill circuit charges capacitors C7 and C9 in series

(Figure 4) when the input line is high.

30127519

FIGURE 4. Two stage Valley-Fill Circuit when AC Line is

High

The peak voltage of a two stage valley-fill capacitor is:

As the AC line decreases from its peak value every cycle,

there will be a point where the voltage magnitude of the AC

line is equal to the voltage that each capacitor is charged. At

this point diode D3 becomes reversed biased, and the ca-

pacitors are placed in parallel to each other (Figure 5), and

VBUCK equals the capacitor voltage.

30127521

FIGURE 5. Two stage Valley-Fill Circuit when AC Line is

Low

A three stage valley-fill circuit performs exactly the same as

two-stage valley-fill circuit except now three capacitors are

now charged in series, and when the line voltage decreases

to:

Diode D3 is reversed biased and three capacitors are in par-

allel to each other.

The valley-fill circuit can be optimized for power factor, volt-

age hold up and overall application size and cost. The

LM3444 will operate with a single stage or a three stage val-

ley-fill circuit as well. Resistor R8 functions as a current

limiting resistor during start-up, and during the transition from

series to parallel connection. Resistors R6 and R7 are 1 MΩ

bleeder resistors, and may or may not be necessary for each

application.

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LM3444

BUCK CONVERTER

The LM3444 is a buck controller that uses a proprietary con-

stant off-time method to maintain constant current through a

string of LEDs. While transistor Q2 is on, current ramps up

through the inductor and LED string. A resistor R3 senses this

current and this voltage is compared to the reference voltage

at FILTER. When this sensed voltage is equal to the reference

voltage, transistor Q2 is turned off and diode D10 conducts

the current through the inductor and LEDs. Capacitor C12

eliminates most of the ripple current seen in the inductor. Re-

sistor R4, capacitor C11, and transistor Q3 provide a linear

current ramp that sets the constant off-time for a given output

voltage.

30127523

FIGURE 6. LM3444 Buck Regulation Circuit

OVERVIEW OF CONSTANT OFF-TIME CONTROL

A buck converter’s conversion ratio is defined as:

Constant off-time control architecture operates by simply

defining the off-time and allowing the on-time, and therefore

the switching frequency, to vary as either VIN or VO changes.

The output voltage is equal to the LED string voltage (VLED),

and should not change significantly for a given application.

The input voltage or VBUCK in this analysis will vary as the

input line varies. The length of the on-time is determined by

the sensed inductor current through a resistor to a voltage

reference at a comparator. During the on-time, denoted by

tON, MOSFET switch Q2 is on causing the inductor current to

increase. During the on-time, current flows from VBUCK,

through the LEDs, through L2, Q2, and finally through R3 to

ground. At some point in time, the inductor current reaches a

maximum (IL2-PK) determined by the voltage sensed at R3 and

the ISNS pin. This sensed voltage across R3 is compared

against the voltage of FILTER, at which point Q2 is turned off

by the controller.

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FIGURE 7. Inductor Current Waveform in CCM

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LM3444

During the off-period denoted by tOFF, the current through L2

continues to flow through the LEDs via D10.

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 ap-

proximately 145°C.

Design Guide

DETERMINING DUTY-CYCLE (D)

Duty cycle (D) approximately equals:

With efficiency considered:

For simplicity, choose efficiency between 75% and 85%.

CALCULATING OFF-TIME

The “Off-Time” of the LM3444 is set by the user and remains

fairly constant as long as the voltage of the LED stack remains

constant. Calculating the off-time is the first step in determin-

ing the switching frequency of the converter, which is integral

in determining some external component values.

PNP transistor Q3, resistor R4, and the LED string voltage

define a charging current into capacitor C11. A constant cur-

rent into a capacitor creates a linear charging characteristic.

Resistor R4, capacitor C11 and the current through resistor

R4 (iCOLL), which is approximately equal to VLED/R4, are all

fixed. Therefore, dv is fixed and linear, and dt (tOFF) can now

be calculated.

Common equations for determining duty cycle and switching

frequency in any buck converter:

Therefore:

With efficiency of the buck converter in mind:

Substitute equations and rearrange:

Off-time, and switching frequency can now be calculated us-

ing the equations above.

SETTING THE SWITCHING FREQUENCY

Selecting the switching frequency for nominal operating con-

ditions is based on tradeoffs between efficiency (better at low

frequency) and solution size/cost (smaller at high frequency).

The input voltage to the buck converter (VBUCK) changes with

both line variations and over the course of each half-cycle of

the input line voltage. The voltage across the LED string will,

however, remain constant, and therefore the off-time remains

constant.

The on-time, and therefore the switching frequency, will vary

as the VBUCK voltage changes with line voltage. A good design

practice is to choose a desired nominal switching frequency

knowing that the switching frequency will decrease as the line

voltage drops and increase as the line voltage increases

(Figure 8).

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FIGURE 8. Graphical Illustration of Switching Frequency

vs VBUCK

The off-time of the LM3444 can be programmed for switching

frequencies ranging from 30 kHz to over 1 MHz. A trade-off

between efficiency and solution size must be considered

when designing the LM3444 application.

The maximum switching frequency attainable is limited only

by the minimum on-time requirement (200 ns).

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LM3444

Worst case scenario for minimum on time is when VBUCK is at

its maximum voltage (AC high line) and the LED string voltage

(VLED) is at its minimum value.

The maximum voltage seen by the Buck Converter is:

INDUCTOR SELECTION

The controlled off-time architecture of the LM3444 regulates

the average current through the inductor (L2), and therefore

the LED string current. The input voltage to the buck converter

(VBUCK) changes with line variations and over the course of

each half-cycle of the input line voltage. The voltage across

the LED string is relatively constant, and therefore the current

through R4 is constant. This current sets the off-time of the

converter and therefore the output volt-second product

(VLED x off-time) remains constant. A constant volt-second

product makes it possible to keep the ripple through the in-

ductor constant as the voltage at VBUCK varies.

30127540

FIGURE 9. LM3444 External Components of the Buck

Converter

The equation for an ideal inductor is:

Given a fixed inductor value, L, this equation states that the

change in the inductor current over time is proportional to the

voltage applied across the inductor.

During the on-time, the voltage applied across the inductor is,

VL(ON-TIME) = VBUCK - (VLED + VDS(Q2) + IL2 x R3)

Since the voltage across the MOSFET switch (Q2) is rela-

tively small, as is the voltage across sense resistor R3, we

can simplify this to approximately,

VL(ON-TIME) = VBUCK - VLED

During the off-time, the voltage seen by the inductor is ap-

proximately:

VL(OFF-TIME) = VLED

The value of VL(OFF-TIME) will be relatively constant, because

the LED stack voltage will remain constant. If we rewrite the

equation for an inductor inserting what we know about the

circuit during the off-time, we get:

Re-arranging this gives:

From this we can see that the ripple current (Δi) is proportional

to off-time (tOFF) multiplied by a voltage which is dominated

by VLED divided by a constant (L2).

These equations can be rearranged to calculate the desired

value for inductor L2.

Where:

Finally:

Refer to “Design Example” section of the datasheet to better

understand the design process.

SETTING THE LED CURRENT

The LM3444 constant off-time control loop regulates the peak

inductor current (IL2). The average inductor current equals the

average LED current (IAVE). Therefore the average LED cur-

rent is regulated by regulating the peak inductor current.

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LM3444

30127525

FIGURE 10. Inductor Current Waveform in CCM

Knowing the desired average LED current, IAVE and the nom-

inal inductor current ripple, ΔiL, the peak current for an appli-

cation running in continuous conduction mode (CCM) is

defined as follows:

Or the LED current would then be,

This is important to calculate because this peak current mul-

tiplied by the sense resistor R3 will determine when the

internal comparator is tripped. The internal comparator turns

the control MOSFET off once the peak sensed voltage reach-

es 750 mV.

Current Limit: The trip voltage on the PWM comparator is

750 mV. However, if there is a short circuit or an excessive

load on the output, higher than normal switch currents will

cause a voltage above 1.27V on the ISNS pin which will trip

the I-LIM comparator. The I-LIM comparator will reset the RS

latch, turning off Q2. It will also inhibit the Start Pulse Gener-

ator and the COFF comparator by holding the COFF pin low.

A delay circuit will prevent the start of another cycle for 180

µs.

VALLEY FILL CAPACITORS

Determining voltage rating and capacitance value of the val-

ley-fill capacitors:

The maximum voltage seen by the valley-fill capacitors is:

This is, of course, if the capacitors chosen have identical ca-

pacitance values and split the line voltage equally. Often a

20% difference in capacitance could be observed between

like capacitors. Therefore a voltage rating margin of 25% to

50% should be considered.

Determining the capacitance value of the valley-fill ca-

pacitors:

The valley fill capacitors should be sized to supply energy to

the buck converter (VBUCK) when the input line is less than its

peak divided by the number of stages used in the valley fill

(tX). The capacitance value should be calculated for the max-

imum LED current.

30127552

FIGURE 11. Two Stage Valley-Ffill VBUCK Voltage

From the above illustration and the equation for current in a

capacitor, i = C x dV/dt, the amount of capacitance needed at

VBUCK will be calculated as follows:

At 60Hz, and a valley-fill circuit of two stages, the hold up time

(tX) required at VBUCK is calculated as follows. The total angle

of an AC half cycle is 180° and the total time of a half AC line

cycle is 8.33 ms. When the angle of the AC waveform is at

30° and 150°, the voltage of the AC line is exactly ½ of its

peak. With a two stage valley-fill circuit, this is the point where

the LED string switches from power being derived from AC

line to power being derived from the hold up capacitors (C7

and C9). 60° out of 180° of the cycle or 1/3 of the cycle the

power is derived from the hold up capacitors (1/3 x 8.33 ms

= 2.78 ms). This is equal to the hold up time (dt) from the

above equation, and dv is the amount of voltage the circuit is

allowed to droop. From the next section (“Determining Maxi-

mum Number of Series Connected LEDs Allowed”) we know

the minimum VBUCK voltage will be about 45V for a 90VAC to

135VAC line. At 90VAC low line operating condition input, ½ of

the peak voltage is 64V. Therefore with some margin the volt-

age at VBUCK can not droop more than about 15V (dv). (i) is

equal to (POUT/VBUCK), where POUT is equal to (VLED x ILED).

Total capacitance (C7 in parallel with C9) can now be calcu-

lated. See “ Design Example" section for further calculations

of the valley-fill capacitors.

Determining Maximum Number of Series Connected

LEDs Allowed:

The LM3444 is an off-line buck topology LED driver. A buck

converter topology requires that the input voltage (VBUCK) of

the output circuit must be greater than the voltage of the LED

stack (VLED) for proper regulation. One must determine what

the minimum voltage observed by the buck converter will be

before the maximum number of LEDs allowed can be deter-

mined. Two variables will have to be determined in order to

accomplish this.

1. AC line operating voltage. This is usually 90VAC to

135VAC for North America. Although the LM3444 can

operate at much lower and higher input voltages a range

is needed to illustrate the design process.

2. How many stages are implemented in the valley-fill circuit

(1, 2 or 3).

In this example the most common valley-fill circuit will be used

(two stages).

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LM3444

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FIGURE 12. AC Line

Figure 12 shows the AC waveform. One can easily see that

the peak voltage (VPEAK) will always be:

The voltage at VBUCK with a valley fill stage of two will look

similar to the waveforms of Figure 11.

The purpose of the valley fill circuit is to allow the buck con-

verter to pull power directly off of the AC line when the line

voltage is greater than its peak voltage divided by two (two

stage valley fill circuit). During this time, the capacitors within

the valley fill circuit (C7 and C8) are charged up to the peak

of the AC line voltage. Once the line drops below its peak

divided by two, the two capacitors are placed in parallel and

deliver power to the buck converter. One can now see that if

the peak of the AC line voltage is lowered due to variations in

the line voltage the DC offset (VDC) will lower. VDC is the low-

est value that voltage VBUCK will encounter.

Example:

Line voltage = 90VAC to 135VAC

Valley-Fill = two stage

Depending on what type and value of capacitors are used,

some derating should be used for voltage droop when the

capacitors are delivering power to the buck converter. With

this derating, the lowest voltage the buck converter will see is

about 42.5V in this example.

To determine how many LEDs can be driven, take the mini-

mum voltage the buck converter will see (42.5V) and divide it

by the worst case forward voltage drop of a single LED.

Example: 42.5V/3.7V = 11.5 LEDs (11 LEDs with margin)

OUTPUT CAPACITOR

A capacitor placed in parallel with the LED or array of LEDs

can be used to reduce the LED current ripple while keeping

the same average current through both the inductor and the

LED array. With a buck topology the output inductance (L2)

can now be lowered, making the magnetics smaller and less

expensive. With a well designed converter, you can assume

that all of the ripple will be seen by the capacitor, and not the

LEDs. One must ensure that the capacitor you choose can

handle the RMS current of the inductor. Refer to

manufacture’s datasheets to ensure compliance. Usually an

X5R or X7R capacitor between 1 µF and 10 µF of the proper

voltage rating will be sufficient.

SWITCHING MOSFET

The main switching MOSFET should be chosen with efficien-

cy and robustness in mind. The maximum voltage across the

switching MOSFET will equal:

The average current rating should be greater than:

IDS-MAX = ILED(-AVE)(DMAX)

RE-CIRCULATING DIODE

The LM3444 Buck converter requires a re-circulating diode

D10 (see the Typical Application circuit Figure 2) to carry the

inductor current during the MOSFET Q2 off-time. The most

efficient choice for D10 is a diode with a low forward drop and

near-zero reverse recovery time that can withstand a reverse

voltage of the maximum voltage seen at VBUCK. For a common

110VAC ± 20% line, the reverse voltage could be as high as

190V.

The current rating must be at least:

ID = 1 - (DMIN) x ILED(AVE)

Or:

Design Example

The following design example illustrates the process of cal-

culating external component values.

Known:

1. Input voltage range (90VAC – 135VAC)

2. Number of LEDs in series = 7

3. Forward voltage drop of a single LED = 3.6V

4. LED stack voltage = (7 x 3.6V) = 25.2V

Choose:

1. Nominal switching frequency, fSW-TARGET = 250 kHz

2. ILED(AVE) = 400 mA

3. Δi (usually 15% - 30% of ILED(AVE)) = (0.30 x 400 mA) =

120 mA

4. Valley fill stages (1,2, or 3) = 2

5. Assumed minimum efficiency = 80%

Calculate:

1. Calculate minimum voltage VBUCK equals:

2. Calculate maximum voltage VBUCK equals:

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3. Calculate tOFF at VBUCK nominal line voltage:

4. Calculate tON(MIN) at high line to ensure that

tON(MIN) > 200 ns:

5. Calculate C11 and R4:

6. Choose current through R4: (between 50 µA and 100 µA)

70 µA

7. Use a standard value of 365 kΩ

8. Calculate C11:

10. Use standard value of 120 pF

11. Calculate ripple current: 400 mA X 0.30 = 120 mA

12. Calculate inductor value at tOFF = 3 µs:

13. Choose C10: 1.0 µF 200V

14. Calculate valley-fill capacitor values: VAC low line =

90VAC, VBUCK minimum equals 60V. Set droop for 20V

maximum at full load and low line.

i) equals POUT/VBUCK (270 mA), dV equals 20V, dt equals

2.77 ms, and then CTOTAL equals 37 µF. Therefore C7 =

C9 = 22 µF

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LM3444

LM3444 Design Example 1

Input = 90VAC to 135VAC, VLED = 7 x HB LED String Application @ 400 mA

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Bill of Materials

Qty Ref Des Description Mfr Mfr PN

1 U1 IC, CTRLR, DRVR-LED, MSOP10 NSC LM3444MM

1 BR1 Bridge Rectifiier, SMT, 400V, 800 mA DiodesInc HD04-T

1 L1 Common mode filter DIP4NS, 900 mA, 700

µH

Panasonic ELF-11090E

1 L2 Inductor, SHLD, SMT, 1A, 470 µH Coilcraft MSS1260-474-KLB

2 L3, L4 Diff mode inductor, 500 mA 1 mH Coilcraft MSS1260-105KL-KLB

1 L5 Bead Inductor, 160Ω, 6A Steward HI1206T161R-10

3 C1, C2, C15 Cap, Film, X2Y2, 12.5MM, 250VAC, 20%, 10

Panasonic ECQ-U2A103ML

1 C4 Cap, X7R, 0603, 16V, 10%, 100 nF MuRata GRM188R71C104KA01D

2 C5, C6 Cap, X5R, 1210, 25V, 10%, 22 µF MuRata GRM32ER61E226KE15L

2 C7, C9 Cap, AL, 200V, 105C, 20%, 33 µF UCC EKXG201ELL330MK20S

1 C10 Cap, Film, 250V, 5%, 10 nF Epcos B32521C3103J

1 C12 Cap, X7R, 1206, 50V, 10%, 1.0 uF Kemet C1206F105K5RACTU

1 C11 Cap, C0G, 0603, 100V, 5%, 120 pF MuRata GRM1885C2A121JA01D

1 D1 Diode, ZNR, SOT23, 15V, 5% OnSemi BZX84C15LT1G

2 D2, D13 Diode, SCH, SOD123, 40V, 120 mA NXP BAS40H

4 D3, D4, D8, D9 Diode, FR, SOD123, 200V, 1A Rohm RF071M2S

1 D10 Diode, FR, SMB, 400V, 1A OnSemi MURS140T3G

1 D12 TVS, VBR = 144V Fairchild SMBJ130CA

1 R2 Resistor, 1206, 1%, 100 kΩPanasonic ERJ-8ENF1003V

1 R3 Resistor, 1210, 5%, 1.8ΩPanasonic ERJ-14RQJ1R8U

1 R4 Resistor, 0603, 1%, 576 kΩPanasonic ERJ-3EKF5763V

2 R6, R7 Resistor, 0805, 1%, 1.00 MΩRohm MCR10EZHF1004

2 R8, R10 Resistor, 1206, 0.0ΩYageo RC1206JR-070RL

1 R9 Resistor, 1812, 0.0Ω

1 RT1 Thermistor, 120V, 1.1A, 50Ω @ 25°CThermometrics CL-140

2 Q1, Q2 XSTR, NFET, DPAK, 300V, 4A Fairchild FQD7N30TF

1 Q3 XSTR, PNP, SOT23, 300V, 500 mA Fairchild MMBTA92

1 J1 Terminal Block 2 pos Phoenix Contact 1715721

1 F1 Fuse, 125V, 1,25A bel SSQ 1.25

www.ti.com 16

LM3444

Physical Dimensions inches (millimeters) unless otherwise noted

MSOP-10 Pin Package (MM)

For Ordering, Refer to Ordering Information Table

NS Package Number MUB10A

SOIC-8 Pin Package (M)

For Ordering, Refer to Ordering Information Table

NS Package Number M08A

17 www.ti.com

LM3444

Notes

LM3444 AC-DC Offline LED Driver

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