LDCQ

LT3592 LINER

Document overview

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Technical content

FEATURES

APPLICATIONS

DESCRIPTION

Range Step-Down LED Driver with 10:1 Dimming The L T®3592 is a fi xed frequency step-down DC/DC con- verter designed to operate as a constant-current source. An external sense resistor monitors the output current allowing accurate current regulation, ideal for driving high current LEDs. The output current can be dimmed by a factor of 10 using an external signal for nighttime brake lights. The high switching frequency offers several advantages by permitting the use of a small inductor and small ceramic capacitors. Small components combined with the L T3592’s 10-pin DFN leadless surface mount package save space and cost versus alternative solutions. The constant switching frequency combined with low-impedance ceramic capaci- tors result in low, predictable output ripple. A wide input voltage range of 3.6V to 36V makes the L T3592 useful in a variety of applications. Current mode PWM architecture provides fast transient response and cycle-by-cycle current limiting. Thermal shutdown provides additional protection. 50/500mA T wo Series Red LED Driver n Wide Input Voltage Range Operation from 3.6V to 36V n Resistor Adjustable 400kHz–2.2MHz Switching Frequency n Shorted and Open LED Protected n Internal Switch Current Sense Resistor n External Resistor Programs LED Current, Pin Selects 10:1 Ratio n 50mA/500mA LED Current Settings n Catch Diode Current Sense to Prevent Runaway at High VIN n Small Thermally Enhanced 10-Lead DFN (2mm × 3mm) and MSOP-10 Packages n Automotive Signal Lighting n Industrial Lighting n Constant-Current, Constant Voltage Supplies Effi ciency for 2 Red LEDs, L = 10μH, 900kHz 10μH 51k

3592 TA01a

4.7μF 1μF 0.4Ω 10k 0.1μF VIN SHDN BRIGHT R T BOOST SW DA CAP OUT VFB L T3592 GND ON BRAKE 140k 900kHz 200/20mV VIN 7V TO 32V L, L T , L TC and L TM are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. INPUT VOL TAGE (V) EFFICIENCY (%) 100 2012 24

3592 TA01b

V (Note 1) TOP VIEW DDB PACKAGE 10-LEAD (3mm s 2mm) PLASTIC DFN

1 VFB

R T BRIGHT SHDN VIN DA θJA = 76°C/W , θJC = 13.5°C/W EXPOSED PAD (PIN 11) IS GND, MUST BE SOLDERED TO PCB R T BRIGHT SHDN VIN DA V FB OUT CAP BOOST SW TOP VIEW MSE PACKAGE 10-LEAD PLASTIC MSOP θJA = 38°C/W , θJC = 8°C/W EXPOSED PAD (PIN 11) IS GND, MUST BE SOLDERED TO PCB PIN CONFIGURATION ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL PART MARKING * PACKAGE DESCRIPTION TEMPERATURE RANGE L T3592EDDB#PBF L T3592EDDB#TRPBF LDCQ 10-Lead (3mm × 2mm) Plastic DFN –40°C to 125°C L T3592IDDB#PBF L T3592IDDB#TRPBF LDCQ 10-Lead (3mm × 2mm) Plastic DFN –40°C to 125°C L T3592EMSE#PBF L T3592EMSE#TRPBF L TDCR 10-Lead Plastic MSOP –40°C to 125°C L T3592IMSE#PBF L T3592IMSE#TRPBF L TDCR 10-Lead Plastic MSOP –40°C to 125°C LEAD BASED FINISH TAPE AND REEL PART MARKING PACKAGE DESCRIPTION TEMPERATURE RANGE L T3592EDDB L T3592EDDB#TR LDCQ 10-Lead (3mm × 2mm) Plastic DFN –40°C to 125°C L T3592IDDB L T3592IDDB#TR LDCQ 10-Lead (3mm × 2mm) Plastic DFN –40°C to 125°C L T3592EMSE L T3592EMSE#TR L TDCR 10-Lead Plastic MSOP –40°C to 125°C L T3592IMSE L T3592IMSE#TR L TDCR 10-Lead Plastic MSOP –40°C to 125°C Consult L TC Marketing for parts specifi ed with wider operating temperature ranges. *The temperature grade is identifi ed by a label on the shipping container . For more information on lead free part marking, go to: http://www.linear .com/leadfree/ For more information on tape and reel specifi cations, go to: http://www.linear .com/tapeandreel/ Operating Temperature Range (Notes 2, 3)

ELECTRICAL CHARACTERISTICS

Note 1: Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. Exposure to any Absolute Maximum Rating condition for extended periods may affect device reliability and lifetime. Note 2: The L T3592E is guaranteed to meet performance specifi cations from 0°C to 125°C junction temperature. Specifi cations over the –40°C to 125°C operating junction temperature range are assured by design, characterization and correlation with statistical process controls. The L T3592I is guaranteed over the full –40°C to 125°C operating junction temperature range. The operating lifetime is derated at junction temperatures greater than 125°C. PARAMETER CONDITIONS MIN TYP MAX UNITS Minimum Input Voltage l 3.25 3.6 V Input Quiescent Current - in Shutdown Not Switching VSHDN = 0.3V 0.1 mA μA CAP to OUT Voltage 0.4Ω CAP to OUT BRIGHT = 1.4V BRIGHT = 0.3V l l 190 200 210 mV mV DA Pin Current to Stop OSC –0.8 –1 –1.2 A Switching Frequency R T = 357k RT = 140k RT = 48.7k 350 800 1.9 400 900 2.2 450 1000 2.5 kHz kHz MHz Maximum Duty Cycle R T = 140k 90 94 % SHDN Input High Voltage 2.3 V SHDN Input Low Voltage 0.3 V BRIGHT Input High Voltage 1.4 V BRIGHT Input Low Voltage 0.3 V Switch Current Limit (Note 4) l 0.85 1.25 1.5 A Switch VCESAT ISW = 500mA 300 mV Boost Pin Current I SW = 500mA 20 30 mA Switch Leakage Current 11 0 μ A Minimum Boost Voltage V OUT = 4V 1.8 2.5 V Boost Diode Forward Voltage I DIO = 50mA 800 mV VFB Voltage OUT = CAP = 4V l 1.185 1.21 1.235 V The l denotes the specifi cations which apply over the full operating temperature range, otherwise specifi cations are at TA = 25°C. VIN = 12V , VBOOST = 16V , VOUT = 4V unless otherwise noted. (Note 2) Note 3: This IC includes overtemperature protection that is intended to protect the device during momentary overload conditions. Junction temperature will exceed the maximum operating junction temperature when overtemperature protection is active. Continuous operation above the specifi ed maximum operating junction temperature may result in device degradation or failure. Note 4: Switch Current Measurements are performed when the outputs are not switching. Slope compensation reduces current limit at higher duty cycles.

TYPICAL PERFORMANCE CHARACTERISTICS Effi ciency (2 Red LEDS, L = 10μH, 900kHz) Effi ciency (1 Red LED, L = 6.8μH, 900kHz) Effi ciency (2 Red LEDs, L = 22μH, 400kHz) Minimum VIN for 500mA Output Current vs VOUT, L = 22μH, f = 400kHz (LED Loads) Minimum VIN for 500mA Output Current vs VOUT, L = 6.8μH, f = 900kHz (LED Loads) Switch Voltage Drop vs Switch Current Switch Voltage Drop at 500mA vs Temperature (TA = 25°C, unless otherwise noted) INPUT VOL TAGE (V) EFFICIENCY (%) 100 2012 24

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BRIGHT (500mA) INPUT VOL TAGE (V) EFFICIENCY (%) 100 2012 24

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BRIGHT (500mA) INPUT VOL TAGE (V) EFFICIENCY (%) 100 2012 24

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BRIGHT (500mA) INPUT VOL TAGE (V) OUTPUT VOL TAGE (V)

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INPUT VOL TAGE (V) OUTPUT VOL TAGE (V)

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SWITCH CURRENT (mA) VIN – VSW (mV) 500 450 400 100 250 200 150 300 350 600

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TEMPERATURE (°C) –50 VIN – VSW (mV) 400 375 300 350 325 275 250 100

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Effi ciency (2 Red LEDs, L = 4.7μH, 2.2MHz) Minimum VIN for 500mA Output Current vs VOUT, L = 22μH, f = 400kHz (LED Loads) INPUT VOL TAGE (V) EFFICIENCY (%) 100 2012 24

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BRIGHT (500mA) INPUT VOL TAGE (V) OUTPUT VOL TAGE (V)

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TYPICAL PERFORMANCE CHARACTERISTICS Current Limit During Soft Start Frequency Foldback Switch Current Limit Switch Current Limit Operating Waveforms Operating Waveforms, Discontinuous Mode (TA = 25°C, unless otherwise noted) TEMPERATURE (°C) –50 UNDERVOL TAGE LOCKOUT (V) 3.4 3.3 3.2 3.1 100

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TEMPERATURE (°C) –50 fSW (kHz) 2300 1700 1900 2100 1500 1300 1100 900 700 500 300 110

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130–30 –10 90 70503010 RT = 357k RT = 140k RT = 48.7k VSHDN (V) 0.5 SWITCH CURRENT LIMIT (mA) 1400 1200 1000 800 600 400 200

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2.51.51 SHDN VOL TAGE (mV) 600 FREQUENCY (kHz) 2500 2000 1500 1000 500 2000

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22001000 1200 1400 1600 1800800 RT = 48.7k DUTY CYCLE (%) SWITCH CURRENT LIMIT (A) 1.4 1.3 1.2 1.1 0.8 0.9 0.7 0.6 0.5

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TEMPERATURE (°C) –50 SWITCH CURRENT LIMIT (A) 1.50 1.40 1.45 1.35 1.30 1.15 1.20 1.25 1.10 1.05 1.00 90 110

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1303010 70 50–30 –10 TYPICAL VSW 5V/DIV VCAP 10mV/DIV AC COUPLED IL 500mA/DIV

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TYPICAL PERFORMANCE CHARACTERISTICS Switching Frequency vs RT VBRIGHT vs VOUT VDIM vs VOUT Boost Diode Voltage vs Current VOUT (V) VCAP – VOUT (mV) 210 205 200 195 190 81 0

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VBRIGHT (mV) VOUT (V) VCAP – VOUT (mV) 81 0

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VDIM (mV) DIODE CURRENT (mA) DIODE FORWARD VOL TAGE (V) 1.0 0.9 0.6 0.7 0.8 0.5 0.4 100 150

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RT (kΩ) FREQUENCY (kHz) 3000 2500 1000 1500 2000 500 300 330

3592 G21

36060 90 120 150 180 210 240 270 (TA = 25°C, unless otherwise noted)

RT (Pin 1): Programs the frequency of the internal oscillator . Connect a resistor from RT to ground. Refer to Table 1 or the Typical Performance Characteristics for resistor values that result in desired oscillator frequencies. BRIGHT (Pin 2): Used to program a 10:1 dimming ratio for the LED current. Drive this pin above 1.4V to command maximum intensity or below 0.3V to command minimum intensity. This pin can be PWMed at 150Hz for brightness control between the 1x and 10x current levels. SHDN (Pin 3): Used to shutdown the switching regulator and the internal bias circuits. This pin can be PWMed at 150Hz for brightness control. V IN (Pin 4): Supplies current to the L T3592’s internal cir- cuitry and to the internal power switches. Must be locally bypassed. For automotive applications, a pi network with a cap from V IN to GND, a series inductor connected between VIN and the power source, and another cap from the far end of the inductor to GND is recommended. DA (Pin 5): Allows the external catch diode current to be sensed to prevent current runaway, such as when VIN is high and the duty cycle is very low. Connect this pin to the anode of the external catch Schottky diode. SW (Pin 6): The SW pin is the output of the internal power switch. Connect this pin to the inductor and the cathode of the switching diode. BOOST (Pin 7): Provides a drive voltage, higher than the input voltage to the internal bipolar NPN power switch. BOOST will normally be tied to the SW pin through a 0.1μF capacitor . An internal Schottky is provided for the boost function and an external diode is not needed. An external Schottky diode should be connected between BOOST and CAP for single LED applications or whenever a higher BOOST voltage is desired. CAP (Pin 8): Output of the step-down converter and also an input to the LED current sense amplifi er . Connect the fi lter capacitor , inductor , and the top of the external LED current sense resistor to this pin. OUT (Pin 9): Drives the LED or LEDs and is the other input to the LED current sense amplifi er . Connect this pin to the anode of the top LED in the string, the bottom of the external LED current sense resistor , and the top of the V FB resistor divider . VFB (Pin 10): The feedback node for the output voltage control loop. Tie this node to a resistor divider between OUT and GND to set the maximum output voltage of the step- down converter according to the following formula: VOUT = 1.21 R1+R2 where R1 connects between OUT and VFB and R2 connects between VFB and GND. GND, EXPOSED PAD (Pin 11): The underside exposed pad metal of the package provides both electrical contact to ground and good thermal contact to the printed circuit board. The device must be soldered to the circuit board for proper operation.

R S Q BOOST BATT VIN SW 5DA L2L2 RT RT

11 GNDSHDN

1.21V RSRSENSE LED1 LED2 R C2AC2BC2C gm = 6 R

The L T3592 is a constant frequency, current mode step- down LED driver . An internal oscillator that is programmed by a resistor from the R T pin to ground enables an RS fl ip-fl op, turning on the internal 1A power switch Q1. An amplifi er and comparator monitor the current fl owing between the V IN and SW pins, turning the switch off when this current reaches a level determined by the voltage at V C. An error amplifi er that servos the V C node has two inputs, one from a voltage measurement and one from a current measurement. An instrumentation amplifi er measures the drop across an external current sense resistor between the CAP and OUT pins and applies a gain of 60 (BRIGHT low for dim mode) or 6 (BRIGHT high for bright mode) to this signal and presents it to one negative error amp input. The output of a external resistor divider between OUT and ground is tied to the V FB pin and presented to a second negative error amp input. Whichever input is higher in voltage will end up controlling the loop, so a circuit in which current control is desired (as for driving a LED) will be set up such that the output of the instrumentation amp will be higher than the V FB pin at the current level that is desired. The voltage feedback loop will act to limit the output voltage and prevent circuit damage if an LED should go open circuit. The positive input to the error amp is a 1.21V reference, so the voltage loop forces the V FB pin to 1.21V and the current loop forces the voltage difference between CAP and OUT to be 200mV for BRIGHT mode and 20mV for DIM mode. A rise in the output of the error amplifi er results in a increase in output current, and a fall in the error amplifi er output means less output current. Current limit is provided by an active clamp on the V C node, and this node is also clamped to the SHDN pin. Soft-start is implemented by ramping the SHDN pin using an external resistor and capacitor . An internal regulator provides power to the control circuitry and also includes an undervoltage lockout to prevent switching when V IN is less than 3.25V . If SHDN is low, the output is disconnected and the input current is less than 2μA. The switch driver operates from the input of the BOOST pin. An external capacitor and internal diode are used to generate a voltage at the BOOST pin that is higher than the input supply, which allows the driver to fully saturate the internal bipolar NPN power switch for effi cient operation. An external diode can be used to make the BOOST drive more effective at low output voltage. The oscillator reduces the L T3592’s operating frequency when the voltage at the OUT pin is low. This frequency foldback helps to control the output current during startup and overload. The anode of the catch diode for the step-down circuit is connected to the DA pin to provide a direct sense of the current in this device. If this diode’s current goes above a level set by an internal catch diode current limit circuit, the oscillator frequency is slowed down. This prevents current runaway due to minimum on time limitations at high V IN voltages. This function can easily be disabled by tying the DA pin and the catch diode anode to ground.

cal Performance Characteristics curve for other values. The DIM mode current is 10% of the BRIGHT mode value. it to interface to logic level control signals. Table 2. Inductor Vendor Information the external current sense resistor between CAP and OUT . Table 1. RT Values for Selector Oscillator Frequencies

conditions (short circuit or startup). of the part. The minimum on time for the L T3592 is ~70ns. when the input voltage is increased to 36V . Figure 2. Figure 3.

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3592 F02

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As the input voltage increases, the inductor current ramps up more quickly, the number of skipped pulses increases, and the output voltage ripple increases. For operation above V IN(MAX), the only component requirement is that they be adequately rated for operation at the intended voltage levels. The L T3592 is robust enough to survive prolonged opera- tion under these conditions as long as the peak inductor current does not exceed 1.2A. Inductor saturation due to high current may further limit performance in this operat- ing regime. Inductor Selection and Maximum Output Current A good fi rst choice for the inductor value is: L = 1.2A  VOUT + 0.2V + VD() ƒ where VD is the forward voltage drop of the catch diode (~0.4V), f is the switching frequency in MHz and L is in μH. With this value, there will be no subharmonic oscillation for applications with 50% or greater duty cycle. For low duty cycle applications in which V IN is more than three times VOUT, a good guide for the minimum inductor value is L = 1.7  VIN VOUT 0.2V() VIN VSW + VD  VOUT + 0.2V + VD() ƒ where V SW is the switch voltage drop (about 0.3V at 500mA). The inductor’s RMS current rating must be greater than your maximum load current and its saturation current should be about 30% higher . For robust operation in fault conditions, the saturation current should be above 1.5A. To keep effi ciency high, the series resistance (DCR) should be less than 0.1Ω. Table 2 lists several inductor vendors. Of course, such a simple design guide will not always re- sult in the optimum inductor for your application. A larger value provides a higher maximum load current and reduces output voltage ripple at the expense of a slower transient response. If your load is lower than 500mA, then you can decrease the value of the inductor and operate with higher ripple current. This allows you to use a physically smaller inductor , or one with a lower DCR resulting in higher effi - ciency. There are several graphs in the Typical Performance Characteristics section of this data sheet that show the maximum load current as a function of input voltage and inductor value for several popular output voltages. Low inductance may result in discontinuous mode operation, which is acceptable, but further reduces maximum load current. For details of the maximum output current and discontinuous mode operation, see Linear Technology Application Note 44. Catch Diode Depending on load current, a 500mA to 1A Schottky di- ode is recommended for the catch diode, D1. The diode must have a reverse voltage rating equal to or greater than the maximum input voltage. The ON Semiconductor MBRA140T3 and Central Semiconductor CMMSH1-40 are good choices, as they are rated for 1A continuous forward current and a maximum reverse voltage of 40V . Input Filter Network For applications that only require a capacitor , bypass V IN with a 1μF or higher ceramic capacitor of X7R or X5R type. Y5V types have poor performance over tempera- ture and applied voltage and should not be used. A 1μF ceramic capacitor is adequate to bypass the L T3592 and will easily handle the ripple current. However , if the input power source has high impedance, or there is signifi cant inductance due to long wires or cables, additional bulk capacitance might be necessary. The can be provided with a low performance (high ESR) electrolytic capacitor in parallel with the ceramic device. Some applications, such as those in automobiles, may require extra fi ltering due to EMI/EMC requirements. In these applications, very effective EMI fi ltering can be pro- vided by a capacitor to ground right at the source voltage, a series ferrite bead, and a pi fi lter composed of a capacitor to ground, a series inductor , and another capacitor directly from the device pin to ground (see the Block Diagram for an example). Typical values for the fi lter components are 10nF for C2C, a ferrite bead that is ~220Ω at 100MHz for L2, 3.3μF for C2B, 10μH for L3, and 1μF for C2A. Step-down regulators draw current from the input sup- ply in pulses with very fast rise and fall times. The input capacitor is required to reduce the resulting voltage ripple

value, possibly exceeding the L T3592’s voltage rating. Technology Application Note 88. when extra damping is required or desired. ripple and small circuit size, are therefore an option. with applied voltage and at temperature extremes. and X5R types. Table 3 lists several capacitor vendors. resulting from a larger output capacitor . Table 3. Capacitor Vendor Information

Figure 4. T ransient Load Response of the L T3592 with Different Output Capacitors Figure 5. T wo Circuits for Generating the Boost Voltage

3592 F05a

3592 F05b

3592 F04

maximum rating of the BOOST pin. Figure 6. Input Voltage Needed to Start at 500mA Output Current vs LED Voltage

3592 F06a

3592 F06c

on some cycles despite the actions of the current loop. current limit, which could be as high as 1.5A. LED at the programmed BRIGHT current.

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3592 F07b

Figure 7. To Soft-Start the L T3592, Add a Resistor and Capacitor to the SHDN Pin

Figure 9. A Well Chosen Input Network Prevents Input Voltage Overshoot and

3493 F09

Figure 8. Circuit to Address Reversed Input and Backpowering Issues

3592 F08

protects against a shorted or reversed input. high as 56V and the input current peaks at 16A. red series LED load in BRIGHT mode operating from 32V . Figure 10. Model for Loop Response

3592 F10

frequency is much lower than the switching frequency. heat from the L T3592 to the ground plane. by the thermal resistance from junction to ambient. Figure 11. A Good PCB Layout Ensures Proper , Low EMI Operation

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Figure 12. Switching T ransient When Going from 50mA to 500mA Current and Back in Voltage Mode tolerate sustained output voltages of up to 20V . the resistive voltage divider to the FB pin.

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Single Red LED Driver with Boost Diode to VIN Due to Low VOUT 15μH 30k

3592 TA02

22μF 1μF 0.4Ω 10k357k 400kHz 0.1μF VIN SHDN BRIGHT R T BOOST SW DA CAP OUT VFB L T3592 1N4148 MBRA120 LUXEON LXK2-PD12-S00GND VIN 5V TO 16V FAUL T ONOFF 6.8μH 51k

3592 TA03

4.7μF 1μF 0.4Ω 10k48.7k 2.2MHz 10μHBEAD 0.1μF CMMSHI-40 VIN SHDN BRIGHT R T BOOST SW DA CAP OUT VFB L T3592 GND 3.3μF10nF VIN 8V TO 32V BRAKE 200/20mV ONOFF LUXEON LXK2-PD12-S00 50mA/500mA T wo Series Red LED Driver 5V Supply with 500mA Current Limit 6.8μH 31.6k

3592 TA04

4.7μF 1μF 0.4Ω 10k48.7k 2.2MHz 0.1μF MBRA140 VIN SHDN BRIGHT R T BOOST SW DA CAP OUT VFB L T3592 GND VIN 8V TO 32V ON

10-Lead Plastic DFN (3mm × 2mm) (Reference L TC DWG # 05-08-1722 Rev Ø) 2.00 ±0.10 (2 SIDES) NOTE: 1. DRAWING CONFORMS TO VERSION (WECD-1) IN JEDEC PACKAGE OUTLINE M0-229 2. DRAWING NOT TO SCALE 3. ALL DIMENSIONS ARE IN MILLIMETERS 4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.15mm ON ANY SIDE 5. EXPOSED PAD SHALL BE SOLDER PLATED 6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION ON THE TOP AND BOTTOM OF PACKAGE 0.40 ± 0.10 BOTTOM VIEW—EXPO SED PAD 0.64 ± 0.05 (2 SIDES) 0.75 ±0.05 R = 0.115 TYPR = 0.05 TYP 2.39 ±0.05 (2 SIDES) 3.00 ±0.10 (2 SIDES) 106 PIN 1 BAR TOP MARK (SEE NOTE 6)

0.200 REF

0 – 0.05 (DDB10) DFN 0905 REV Ø 0.25 ± 0.05 2.39 ±0.05 (2 SIDES) RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS 0.64 ±0.05 (2 SIDES) 1.15 ±0.05 0.70 ±0.05 2.55 ±0.05 PACKAGE OUTLINE 0.25 ± 0.05

0.50 BSC

R = 0.20 OR 0.25 × 45° CHAMFER

Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However , no responsibility is assumed for its use. Linear Technology Corporation makes no representa- tion that the interconnection of its circuits as described herein will not infringe on existing patent rights. PACKAGE DESCRIPTION 10-Lead Plastic MSOP (Reference L TC DWG # 05-08-1664) MSOP (MSE) 0908 REV C 0.53 p 0.152 (.021 p .006) SEATING PLANE 0.18 (.007) 1.10 (.043) MAX 0.17 – 0.27 (.007 – .011) TYP 0.86 (.034) REF 0.50 (.0197) BSC 12 3 45 4.90 p 0.152 (.193 p .006) 0.497 p 0.076 (.0196 p .003) REF8910 7 6 3.00 p 0.102 (.118 p .004) (NOTE 3) 3.00 p 0.102 (.118 p .004) (NOTE 4) NOTE: 1. DIMENSIONS IN MILLIMETER/(INCH) 2. DRAWING NOT TO SCALE 3. DIMENSION DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS. MOLD FLASH, PROTRUSIONS OR GATE BURRS SHALL NOT EXCEED 0.152mm (.006") PER SIDE 4. DIMENSION DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSIONS. INTERLEAD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.152mm (.006") PER SIDE 5. LEAD COPLANARITY (BOTTOM OF LEADS AFTER FORMING) SHALL BE 0.102mm (.004") MAX 0.254 (.010) 0o – 6o TYP DETAIL “A” DETAIL “A” GAUGE PLANE 5.23 (.206) MIN 3.20 – 3.45 (.126 – .136) 0.889 p 0.127 (.035 p .005) RECOMMENDED SOLDER PAD LAYOUT 0.305 p 0.038 (.0120 p .0015) TYP 2.083 p 0.102 (.082 p .004) 2.794 p 0.102 (.110 p .004) 0.50 (.0197) BSC BOTTOM VIEW OF EXPOSED PAD OPTION 1.83 p 0.102 (.072 p .004) 2.06 p 0.102 (.081 p .004) 0.1016 p 0.0508 (.004 p .002) DETAIL “B” DETAIL “B” CORNER TAIL IS PART OF THE LEADFRAME FEATURE. FOR REFERENCE ONL Y NO MEASUREMENT PURPOSE

0.05 REF

0.29 REF

Linear Technology Corporation 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 ● FAX: (408) 434-0507 ● www.linear .com © LINEAR TECHNOLOGY CORPORATION 2008 LT 1108 REV A • PRINTED IN USA RELATED PARTS PART NUMBER DESCRIPTION COMMENTS L T1932 Constant Current, 1.2MHz, High Effi ciency White LED Boost Regulator VIN(MIN) = 1V , VIN(MAX) = 10V , VOUT(MAX) = 34V , Dimming Analog/PWM, ISD < 1μA, ThinSOT™ Package L T3465/ L T3465 A Constant Current, 1.2/2.7MHz, High Effi ciency White LED Boost Regulator with Integrated Schottky Diode VIN(MIN) = 2.7V , VIN(MAX) = 16V , VOUT(MAX) = 34V , Dimming Analog/PWM, ISD < 1μA, ThinSOT Package L T3466/ L T3466-1 Dual Constant Current, 2MHz, High Effi ciency White LED Boost Regulator with Integrated Schottky Diode VIN(MIN) = 2.7V , VIN(MAX) = 24V , VOUT(MAX) = 40V , Dimming 5mA, ISD < 16μA, 3mm × 3mm DFN-10 Package L T3474/ L T3474-1 36V , 1A (ILED), 2MHz,Step-Down LED Driver V IN(MIN) = 4V , VIN(MAX) = 36V , VOUT(MAX) = 13.5V , Dimming 400:1 T rue Color PWM, ISD < 1μA, TSSOP-16E Package L T3475/ L T3475-1 Dual 1.5A(ILED), 36V , 2MHz,Step-Down LED Driver V IN(MIN) = 4V , VIN(MAX) = 36V , VOUT(MAX) = 13.5V , Dimming 3,000:1 T rue Color PWM, ISD < 1μA, TSSOP-20E Package L T3476 Quad Output 1.5A, 2MHz High Current LED Driver with 1,000:1 Dimming VIN(MIN) = 2.8V , VIN(MAX) = 16V , VOUT(MAX) = 36V , Dimming 1,000:1 T rue Color PWM, ISD < 10μA, 5mm × 7mm QFN-10 Package L T3478/ L T3478-1 4.5A, 2MHz High Current LED Driver with 3,000:1 Dimming V IN(MIN) = 2.8V , VIN(MAX) = 36V , VOUT(MAX) = 40V , Dimming 1,000:1 T rue Color PWM, ISD < 10μA, 5mm × 7mm QFN-10 Package L T3486 Dual 1.3A , 2MHz High Current LED Driver V IN(MIN) = 2.5V , VIN(MAX) = 24V , VOUT(MAX) = 36V , Dimming 1,000:1 T rue Color PWM, ISD < 1μA, 5mm × 3mm DFN, TSSOP-16E Package L T3491 Constant Current, 2.3MHz, High Effi ciency White LED Boost Regulator with Integrated Schottky Diode VIN(MIN) = 2.5V , VIN(MAX) = 12V , VOUT(MAX) = 27V , Dimming 300:1 T rue Color PWM, ISD < 8μA, 2mm × 2mm DFN-6, SC70 Package L T3496 T riple Output 750mA, 2.1 MHz High Current LED Driver with 3,000:1 Dimming VIN(MIN) = 3V , VIN(MAX) = 30V , VOUT(MAX) = 40V , Dimming 3,000:1 T rue Color PWM, ISD < 1μA, 4mm × 5mm QFN-28 Package L T3497 Dual 2.3MHz, Full Function LED Driver with Integrated Schottkys and 250:1 T rue Color PWM Dimming VIN(MIN) = 2.5V , VIN(MAX) = 10V , VOUT(MAX) = 32V , Dimming 250:1 T rue Color PWM, ISD < 12μA, 2mm × 3mm DFN-10 Package L T3498 20mA LED Driver and OLED Driver Integrated Schottkys V IN(MIN) = 2.5V , VIN(MAX) = 12V , VOUT(MAX) = 32V , Dimming Analog/PWM, ISD < 8.5μA, 2mm × 3mm DFN-10 Package L T3517 1.3A, 2.5MHz High Current LED Driver with 3,000:1 Dimming V IN(MIN) = 3V , VIN(MAX) = 30V , Dimming 3,000:1 T rue Color PWM, ISD < 1μA, 4mm × 4mm QFN-16 Package L T3518 2.3A, 2.5MHz High Current LED Driver with 3,000:1 Dimming V IN(MIN) = 3V , VIN(MAX) = 30V , Dimming 3,000:1 T rue Color PWM, ISD < 1μA, 4mm × 4mm QFN-16 Package L T3590 48V , 850kHz, 50mA Step-Down LED Driver VIN(MIN) = 4.5V , VIN(MAX) = 50V , Dimming 0.4, ISD < 15μA, 2mm × 2mm L T3591 Constant Current, 1MHz, High Effi ciency White LED Boost Regulator with Integrated Schottky Diode and 80:1 T rue Color PWM Dimming V IN(MIN) = 2.5V , VIN(MAX) = 12V , VOUT(MAX) = 40V , Dimming 80:1 T rue Color PWM, ISD < 9μA, 3mm × 2mm DFN-8 Package ThinSOT is a trademark of Linear Technology Corporation.