3598

LT3598 LINER

Document overview

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Technical content

FEATURES

APPLICATIONS

DESCRIPTION

with 1.5% Current Matching The L T®3598 is a fi xed frequency step-up DC/DC converter designed to drive up to six strings of LEDs at an output voltage up to 44V . LED dimming can be achieved with analog dimming on the CTRL pin, and with pulse width modulation dimming on the PWM pin. The L T3598 accu- rately regulates LED current even when the input voltage is higher than the LED output voltage. The switching fre- quency is programmable from 200kHz to 2.5MHz through an external resistor . Additional features include programmable overvoltage protection, switching frequency synchronization to an external clock, LED current derating based on junction temperature and/or LED temperature, LED string disable control, OPENLED alert pin and output voltage limiting when all LED strings are disconnected. The L T3598 is available in a thermally enhanced 24-pin (4mm × 4mm) QFN package. 90% Effi cient LED Driver for 60 White LEDs n T rue Color PWM™ Dimming Delivers Up to 3000:1 Dimming Ratio n Drives Six Strings of LEDs at Up to 30mA n 1.5% Accurate LED Current Matching n Wide Input Voltage Range: 3.2V to 30V n Output Voltage Up to 44V n Regulates Current Even When V IN > VOUT n Disconnects LEDs in Shutdown n Programmable Open LED Protection (Regulated) n OPENLED Alert Pin n Programmable LED Current Derating n Adjustable Frequency: 200kHz to 2.5MHz n Synchronizable to an External Clock n Parallel Channels for Higher Current per LED String n Thermally Enhanced 4mm × 4mm QFN Package n Notebook Computer Display n Medium Size Displays n Automotive LCD Display LED Current Matching L T, L TC and L TM are registered trademarks of Linear Technology Corporation. True Color PWM is a trademark of Linear Technology Corporation. All other trademarks are the property of their respective owners. Protected by U.S. Patents, including 7199560, 7321203. 2.61k 2.2μF 10μH 4.7μF 15nF 20mA

3598 TA01a

VO_SW FBOPENLED PWM SHDN RT SYNC CTRL VREF LED1 LED2 LED3 LED4 LED5 LED6 VOUTSW VIN VCSS GNDTSET ISET 1.00M 30.9k PVIN 8V TO 40V 2.2μF VIN 14.7k 10nF47pF 100k 100k 10k 51.1k 100k 60.4k PWM SHDN SYNC TEMPERATURE (°C) –50 MATCHING (%) 0.5 1.0 –0.5 05 0–25 25 75 100 125 –1.0 –1.5 1.5

3598 TA01b

PIN CONFIGURATION ABSOLUTE MAXIMUM RATINGS V PWM, SYNC, CTRL, RT , SS, V Operating Junction Temperature Range (Note 1) 24 23 22 21 20 19 7 8 9 TOP VIEW UF PACKAGE 24-LEAD (4mm × 4mm) PLASTIC QFN 10 11 12 18LED1 LED2 LED3 LED4 LED5 LED6 V REF SS RT PWM SYNC NC VO_SW VOUT SW V IN SHDN GND OPENLED I SET CTRL VC FB TSET TJMAX = 125°C, θJA = 37°C/W EXPOSED PAD (PIN 25) IS GND, MUST BE SOLDERED TO PCB ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE L T3598EUF#PBF L T3598EUF#TRPBF 3598 24-Lead (4mm × 4mm) Plastic QFN –40°C to 125°C L T3598IUF#PBF L T3598IUF#TRPBF 3598 24-Lead (4mm × 4mm) Plastic QFN –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 . Consult L TC Marketing for information on non-standard lead based fi nish parts. 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/

ELECTRICAL CHARACTERISTICS

PARAMETER CONDITIONS MIN TYP MAX UNITS Minimum Operating Voltage 3 3.2 V Maximum Operating Voltage 30 V Reference Voltage l 1.216 1.210 1.230 1.260 1.260 V V Reference Voltage Line Regulation 3 < V IN < 30V , VC = 0.3V 0.01 0.03 %/V Maximum VREF Pin Current Out of Pin 200 μA FB Pin Bias Current V FB = 1.230V (Note 3) 100 250 nA FB Error Amp T ransconductance ΔI = 5μA 300 μmhos FB Error Amp Voltage Gain 600 V/V FB Pin Voltage 1.22 1.24 1.26 V Current Loop Amp T ransconductance 21 μmhos The l denotes the specifi cations which apply over the full operating temperature range, otherwise specifi cations are at TA = 25°C. VIN = 5V , VSHDN = VIN unless otherwise noted. (Note 2)

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 T3598E 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, The l denotes the specifi cations which apply over the full operating temperature range, otherwise specifi cations are at TA = 25°C. VIN = 5V , VSHDN = VIN unless otherwise noted. (Note 2) PARAMETER CONDITIONS MIN TYP MAX UNITS Current Loop Amp Voltage Gain 80 V/V VC Sink Current 10 μA Quiescent Current V SHDN = 5V , PWM = 0V , Not Switching 3.5 5 mA Quiescent Current in Shutdown V SHDN = 0V 0 1 μA LED Current R ISET = 14.7kΩ 19.5 20 20.7 mA LED String Current Matching 20mA LED Current l ±0.5 ±1.5 % LED Open Detection Threshold 0.2 0.25 V OPENLED Sink Current 2m A Minimum LED Regulation Voltage 0.8 V LED1-6 Leakage Current V LED1-6 = 1V , VOUT = 5V , PWM = 0V VLED1-6 = 42V , VOUT = 44V , PWM = 0V 0.1 0.2 μA μA CTRL Pin Bias Current V CTRL = 0.8V (Note 4) 50 125 nA Switching Frequency RT = 309kΩ RT = 51.1kΩ RT = 14.7kΩ 171 0.9 2.25 190 2.5 209 1.1 2.75 kHz MHz MHz T SET Voltage 602 mV Maximum Switch Duty Cycle RT = 309kΩ RT = 51.1kΩ RT = 14.7kΩ l Switch Current Limit (Note 5) 1.5 2 2.5 A Switch V CESAT ISW = 0.5A 0.12 V Switch Leakage Current V SW = 40V 0.2 5 μA SHDN Pin Current V SHDN = 0V , VIN = 0V VSHDN = 5V , VIN = 5V 0.1 μA μA SHDN Voltage High 1.6 V SHDN Voltage Low 0.4 V Soft-Start Charging Current V SS = 0.1V 5 10 15 μA PWM Input High Voltage 1V PWM Input Low Voltage 0.4 V PWM Pin Bias Current PWM = 3.3V 0.1 1 μA SYNC Input High Voltage 1.5 V SYNC Input Low Voltage 0.4 V SYNC Pin Bias Current SYNC = 0V SYNC = 3.3V 0.1 μA μA V O_SW Switch Resistance 1000 Ω characterization and correlation with statistical process controls. The L T3598I is guaranteed over the full –40°C to 125°C operating junction temperature range. Note 3: Current fl ows out of FB pin. Note 4: Current fl ows out of CTRL pin. Note 5: Current limit guaranteed by design and/or correlation to static test. Current limit is independent of duty cycle and is guaranteed by design.

TYPICAL PERFORMANCE CHARACTERISTICS SHDN Pin Turn-On Threshold SHDN Pin Current Quiescent Current Reference Voltage Oscillator Frequency Current Limit VCESAT Soft-Start Pin Current Feedback Pin Voltage TEMPERATURE (°C) –50 SHDN THRESHOLD (V) 1.4 1.3 05 0–25 25 75 100 125 1.2 1.5

3598 G01

VSHDN (V) SHDN PIN CURRENT (μA) 10 20 25 5 15 30 35

3598 G02

125°C –50°C 25°C TEMPERATURE (°C) –50 QUIESCENT CURRENT (mA) 05 0–25 25 75 100 125

3598 G03

TEMPERATURE (°C) –50 REFERENCE VOL TAGE (V) 1.230 1.235 1.225 1.220 05 0–25 25 75 100 125 1.215 1.240

3598 G04

VIN = 40V VIN = 30V VIN = 5V TEMPERATURE (°C) –50 OSCILLATOR FREQUENCY (MHz) 2.0 2.5 1.5 1.0 05 0–25 25 75 100 125 0.5 3.0

3598 G05

2.5MHz 1MHz 200kHz TEMPERATURE (°C) –50 CURRENT (A) 2.0 2.4 1.6 1.2 05 0–25 25 75 100 125 0.8 0.4 2.8

3598 G06

TEMPERATURE (°C) –50 ISS (μA) 12.5 10.0 05 0–25 25 75 100 125 7.5 5.0 15.0

3598 G08

TEMPERATURE (°C) –50 FEEDBACK VOL TAGE (V) 1.23 1.22 05 0–25 25 75 100 125 1.21 1.20 1.24

3598 G09

VC = 1.5V VC = 1V SWITCH CURRENT (A) VCESAT (V) 0.30 0.35 0.40 0.25 0.20 0.05 0.15 0.10

3598 G07

125°C –50°C 25°C

TYPICAL PERFORMANCE CHARACTERISTICS LED Current vs PWM Duty Cycle LED Current vs Temperature LED Current vs CTRL Voltage LED Current vs Temperature OPENLED Sink Current LED Current Waveforms (0.1% PWM) LED Current Waveforms (90% PWM) LED Current Waveforms (0.1% PWM) LED Current Waveforms (90% PWM) PWM DUTY CYCLE (%) 0.01

0.001 LED CURRENT (mA)

11 00.1 100

3598 G10

0.1 0.01 TEMPERATURE (°C) –50 LED CURRENT (mA) 20.1 20.2 20.0 19.9 05 0–25 25 75 100 125 19.8 19.7 20.3

3598 G11

CTRL VOLTAGE (V) LED CURRENT (mA) 1.0

3598 G12

TEMPERATURE (°C) –50 MATCHING (%) 0.5 1.0 0.0 –0.5 05 0–25 25 75 100 125 –1.0 –1.5 1.5

3598 G13

TEMPERATURE (°C) –50 OPENLED CURRENT (mA) 2.0 2.5 1.5 1.0 05 0–25 25 75 100 125 0.5 3.0

3598 G14

20μs/DIV PWM 5V/DIV SW 20V/DIV ILED1 50mA/DIV IL 1A/DIV

3598 G15

2μs/DIV PWM 5V/DIV SW 20V/DIV ILED1 50mA/DIV IL 1A/DIV

3598 G16

100μs/DIV PWM 5V/DIV SW 20V/DIV ILED1 50mA/DIV IL 1A/DIV

3598 G17

5μs/DIV PWM 5V/DIV SW 20V/DIV ILED1 50mA/DIV IL 1A/DIV

3598 G18

LED1-6 (Pins 1, 2, 3, 4, 5, 6): LED String Output. Connect the bottom cathode of each LED string to these pins. Tie pins to V OUT if the string is not used. OPENLED (Pin 7): Open LED Flag When Any LED String Opens. The output is open-collector . Tie a resistor to other supply for open LED fl ag function. I SET (Pin 8): Programs LED Current for Each String. Con- nect a 14.7k resistor between I SET and GND to program each LED string current to 20mA. A 47pF capacitor on the I SET pin reduces current ripple in each LED string. CTRL (Pin 9): LED Current Control. If the CTRL pin is not used, tie this pin to VREF through a 10k to 20k resistor . VC (Pin 10): Error Amplifi er Output Pin. Tie the external compensation network to this pin. FB (Pin 11): Feedback Pin for Overvoltage Protection. Reference voltage is 1.230V . Connect the resistive divider tap here. Minimize trace area at FB. Set V OUT according to VOUT = 1.230(1 + R2/R1) when overvoltage protection occurs (see Figure 2). TSET (Pin 12): An external resistor divider from VREF pro- grams a decrease in LED current versus internal junction temperature (setting temperature breakpoint and slope). If the T SET pin is not used, tie this pin to VREF. NC (Pin 13): No Connection. SYNC (Pin 14): Frequency Synchronization Pin. This input allows for synchronizing the operating frequency to an external clock. The RT resistor should be chosen to program a switching frequency 20% slower than SYNC pulse frequency. This pin should be grounded if this feature is not used. PWM (Pin 15): Input Pin for PWM Dimming Control. Above 1V allows converter switching and below 1V disables switching with V C pin level maintained. A PWM signal driving the PWM pin provides accurate dimming control. The PWM signal can be driven from 0V to 5V . If unused, the pin should be connected to VREF. RT (Pin 16): A resistor to ground programs switching frequency between 200kHz and 2.5MHz. For SYNC func- tion, choose the resistor to program a frequency 20% slower than the SYNC pulse frequency. Do not leave this pin open. SS (Pin 17): Soft-Start Pin. Place a soft-start capacitor here. Upon start-up, a 10μA current charges the capacitor . Use a larger capacitor for slower start-up. Leave open if not used. V REF (Pin 18): Bandgap Voltage Reference. Internally set to 1.230V . This pin can supply up to 100μA. Can be used to program the CTRL pin voltage using resistor dividers to ground. GND (Pin 19): Ground. Tie directly to local ground plane. SHDN (Pin 20): Shutdown Pin. Tie to 1.6V or more to en- able the device. Tie below 0.4V or less to disable device. Do not fl oat this pin. V IN (Pin 21): Input Supply Pin. Must be locally bypassed with a capacitor to ground. SW (Pin 22): Switch Pin. This is the collector of the in- ternal NPN power switch. Minimize the metal trace area connected to this pin to minimize EMI. V OUT (Pin 23): Output Pin. This pin provides power to all LEDs. VO_SW (Pin 24): Drain of an Internal PMOS. The internal PMOS disconnects the feedback resistors from the VOUT pin during shutdown and the PWM transitioned to low. Exposed Pad (Pin 25): Ground. The Exposed Pad must be soldered to the PCB.

3598 F01

Figure 1. Block Diagram

The L T3598 uses a constant-frequency, peak current mode control scheme to provide excellent line and load regulation. Each string can drive up to 30mA with 1.5% matching ac- curacy between strings. Operation can be best understood by referring to the Block Diagram in Figure 1. L T3598 has a built-in boost converter which converts the input voltage to a higher output voltage to drive LEDs. The LED strings are connected to current sources where the current level is set with an external resistor on the I SET pin. The LED1 to LED6 voltages are monitored for output voltage regulation. During normal operation, when all LEDs are used, the lowest LED pin voltage (LED1 to LED6) is used to regulate the output voltage to ensure all LED strings have enough voltage to run the programmed current. For any unused LED strings, tie their LED pins to V OUT. An unused LED string is no longer in the regulation loop, nor does it affect open LED detection. Never allow unused LED strings to be left open. The basic loop uses a pulse from an internal oscillator to set the SR latch and turn on the internal power NPN switch Q1. The signal at the noninverting input of the PWM comparator (A2 slope) is proportional to the sum of the switch current and oscillator ramp. When slope exceeds V C (the output of the gm amplifi er), the PWM comparator resets the latch. The switch is then turned off, causing the inductor current to lift the SW pin and turn on an external Schottky diode connected to the output. Inductor current fl ows via the Schottky diode charging the output capaci- tor . The switch is turned on again at the next reset cycle of the internal oscillator . During normal operation, the V C voltage controls the peak switch current limit and, hence, the inductor current available to the output LEDs. Dimming of the LEDs is accomplished by pulsing the LED current using the PWM pin. When the PWM pin is low, switching is disabled and the error amplifi er is turned off so that it does not drive the V C pin. Also, all internal loads on the VC pin are disabled so that the state of the VC pin is maintained on the external compensation capacitor . This feature reduces transient recovery time. When the PWM input again transitions high, the peak switch current returns to the correct value. The L T3598 uses the FB pin to provide overvoltage protec- tion when all LED strings are open. There is an internal PMOS switch between V OUT and VO_SW that is controlled by the PWM signal. During the PWM off-period, this PMOS is turned off, allowing for higher dimming range and lower current during shutdown. A resistor divider is connected between the V O_SW pin and ground, which sets the overvoltage protection voltage. If the LED1-6 pin voltage is below 0.2V (for a certain delay after 80% of the programmed output voltage is reached), the string is treated as an open LED string. As a result, OPENLED lag is set. If a LED string is open in the middle of the operation, the regulation will continue. OPENLED detection is disabled during the start-up phase to avoid erratic fl ag generation. An LED string that is dis- abled by connecting its LED pin to V OUT is not an open LED condition. During normal operation, if an LED string is open and has the lowest LED pin voltage, the output volt- age will regulate itself to fi nd another LED string that has the lowest LED pin voltage at about 0.8V . If the open LED string has an LED voltage above 0.8V , the output voltage will remain the same. When the LED string is open, it is no longer in the regulation loop. The OPENLED detection is active only when the PWM signal is enabled. To avoid spurious OPENLED detection and high PWM dimming ratio, more output capacitance is recommended to allow less voltage drop on V OUT. During start-up, 10μA of current charges the external soft-start capacitor . The SS pin directly limits the rate of voltage rise on the V C pin, which in turn, limits the peak switch current. Soft-start also enables the switch- ing frequency foldback to provide a clean start-up for the L T3598. Current limit protects the power switch and external components.

core inductors should be used to obtain the best effi ciency. current greater than its rated value without damaging it. the inductor can reliably conduct. Table 1. Recommended Inductors designs. Table 2 lists some suggested manufacturers. their entire selection of ceramic parts. Table 2. Recommended Ceramic Capacitor Manufacturers must exceed the application’s average output current. diodes with high voltage and current ratings. Table 3. Suggested Diodes

FB resistors taking this resistance into account. Figure 2. Overvoltage Protection resistor can be selected from 10k to 100k. sponding programmed LED current. Table 4. RISET Value Selection for LED Current Figure 3. RISET Value Selection for LED Current

3598 F02

3598 F03

the CTRL pin or the PWM pin. 1V , it has no effect on the LED current. Figure 4. LED Current vs CTRL Voltage Figure 5. LED Current vs CTRL Figure 6. LED Current Using PWM Dimming

3598 F05

3598 F06

3598 F04

T rue Color PWM is a registered trademark of Linear Technology Corporation.

resistance in the divider for the CTRL pin. is connected as closely as possible to the LED strings. Table 5. NTC Resistor Manufacturers/Distributors the effects of the NTC resistor overtemperature. with complete data over a wide range of temperatures.

3598 F07

and the LED strings under worst-case conditions. to approximately 5% of the full LED current. shows commonly used values for R1 and R2. Table 6. TSET Junction Temperature Figure 8. Programming the TSET Pin Figure 9. TSET Pin Threshold

3598 F08

500 VTSET THRESHOLD (mV)

3598 F09

values and corresponding frequencies. losses within the IC should be considered. Table 7. Switching Frequency frequency 20% slower than the SYNC pulse frequency. Figure 10. Switching Frequency

3598 F10

the OPENLED can sink is typically 2mA. OUT, the string will not be in any fault detection. Figure 11. OPENLED Connection internal NPN devices serving as constant-current sources. very dissimilar , there can be signifi cant power dissipation. paid to the PCB board layout and component placement. proper layout of high frequency switching paths is essential. the switching regulator to minimize interplane coupling. Good grounding is essential in LED fault detection.

3598 F11

10μH D1 4.7μF

3598 TA02a

VO_SW FB OPENLED PWM SHDN SYNC LED1 LED2 LED3 LED4 LED5 LED6 VOUTSWVIN 1.00M 30.9k 14.7k 100k C1: TAIYO YUDEN GMK325BJ225ML C2: MURATA GRM32ER71H475K C3: TAIYO YUDEN LMK212BJ225MG D1: DIODES, INC. B240A L1: W ÜRTH ELEKTRONIK 744777410 RNTC: MURATA NCP18WF104J03RB RNTC 100k RHOT 10k 100k PWM SHDN SYNC 2.2μF PVIN 6V TO 40V 2.2μF VIN RC 2.61k CC 15nF RT CTRL VREF VCSS GNDTSET ISET 0.1μFC5 47pF 51.1k 60.4k 20mA LED Driver for 40 White LEDs with T wo Channels Unused Effi ciency (PWM Dimming) TOTAL LED CURRENT (mA) EFFICIENCY (%) 20 4010 90 30 50 8060

3598 TA02b

PVIN = 25V PVIN = 12V

LED Driver for 30 White LEDs with 60mA Each String 10μH D1 4.7μF

3598 TA03a

VO_SW FB OPENLED PWM SHDN SYNC LED1 LED2 LED3 LED4 LED5 LED6 VOUTSWVIN 1.00M 30.9k PWM SHDN SYNC CTRLCTRL 100k 2.2μF PVIN 6V TO 40V 2.2μF VIN 9.76k 100k C1: TAIYO YUDEN GMK325BJ225ML C2: MURATA GRM32ER71H475KA88L C3: TAIYO YUDEN LMK212BJ225MG D1: VISHAY SS3H9 L1: W ÜRTH ELEKTRONIK 744777410 RNTC: MURATA NCP18WF104J03RB RHOT 10k RT CTRL VREF VCSS GNDTSET ISET 0.1μFC5 47pF 51.1k 60mA RNTC 100k RC 2.61k CC 15nF 60.4k Effi ciency (PWM Dimming) Dimming Range (1000:1 PWM) at 125°C Junction Temperature, 10ms Period TOTAL LED CURRENT (mA) EFFICIENCY (%) 140 40 8020 180 60 100 160120 100

3598 TA03b

PVIN = 25V PVIN = 12V 2μs/DIV PWM 5V/DIV SW 20V/DIV ILED1 100mA/DIV 3598

Auto Battery Powered Driver for 20 LEDs with 90mA Each String Effi ciency 4.7μH 4.7μF

3598 TA04a

VO_SW FB OPENLED RT LED1 LED2 LED3 LED4 LED5 LED6 VOUTSWVIN R10 20k CTRL VREF PWM SHDN SYNC PWM SHDN CTRLCTRL 100k PVIN 6V TO 40V 2.2μF VIN 1.00M 30.9k 2.2μF 9.76k C1: NIPPON CHEMI-CON KTS500B225M32NOTOO C2: MURATA GRM32ER71H475KA88L C3: TAIYO YUDEN LMK212BJ225MG D1: VISHAY SS3H9 L1: W ÜRTH ELEKTRONIK 7447785004 VCSS GNDTSET ISET 0.1μFC5 56pF 51.1k 90mA 100k R C 5.11k CC 6.8nF 60.4k Dimming Range 1000:1 PWM, 10ms Period (125°C Junction Temperature) TOTAL LED CURRENT (mA) EFFICIENCY (%) 140 40 8020 180 60 100 160120

3598 TA04b

5μs/DIV PWM 5V/DIV ILED1 100mA/DIV

3598 TA04c

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 4.00 ± 0.10 (4 SIDES) NOTE: 1. DRAWING PROPOSED TO BE MADE A JEDEC PACKAGE OUTLINE MO-220 VARIATION (WGGD-X)—TO BE APPROVED 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, IF PRESENT 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 PIN 1 TOP MARK (NOTE 6) 0.40 ± 0.10 2423 BOTTOM VIEW—EXPOSED PAD 2.45 ± 0.10 (4-SIDES) 0.75 ± 0.05 R = 0.115 TYP 0.25 ± 0.05

0.50 BSC

0.200 REF

0.00 – 0.05 (UF24) QFN 0105 RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS 0.70 ±0.05 0.25 ±0.05 2.45 ± 0.05 (4 SIDES)3.10 ± 0.05 4.50 ± 0.05 PACKAGE OUTLINE PIN 1 NOTCH R = 0.20 TYP OR 0.35 × 45° CHAMFER 24-Lead Plastic QFN (4mm × 4mm) (Reference L TC DWG # 05-08-1697)

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 0908 • PRINTED IN USA L1, 10μH D1 4.7μF VO_SW FB OPENLED PWM SHDN SYNC LED1 LED2 LED3 LED4 LED5 LED6 VOUTSWVIN PWM SHDN SYNC 100k PVIN 8V TO 40V 2.2μF VIN 20mA 1.00M 30.9k 14.7k 100k R HOT 10k 2.2μF RT CTRL VREF VCSS GNDTSET ISET 47pF 51.1k 10nF R NTC 100k RC 2.61k CC 15nF 60.4k RELATED PARTS TYPICAL APPLICATION PART NUMBER DESCRIPTION COMMENTS L T3474/ L T3474-1 36V , 1A (ILED), 2MHz, Step-Down LED Driver V IN: 4V to 36V , VOUT(MAX) = 13.5V , T rue Color PWM Dimming = 400:1, ISD < 1μA, TSSOP-16E Package L T3475/ L T3475-1 Dual 1.5A (ILED), 36V , 2MHz, Step-Down LED Driver V IN: 4V to 36V , VOUT(MAX) = 13.5V , T rue Color PWM Dimming = 3000:1, ISD < 1μA, TSSOP-20E Package L T3476 Quad Output 1.5A, 2MHz High Current LED Driver with 1000:1 Dimming VIN: 2.8V to 16V , VOUT(MAX) = 36V , T rue Color PWM Dimming = 1000:1, ISD < 10μA, 5mm × 7mm QFN-10 Package L T3477 3A, 42V , 3MHz Boost, Buck-Boost, Buck LED Driver V IN: 2.5V to 25V , VOUT(MAX) = 40V , Dimming = Analog/PWM, ISD < 1μA, QFN and TSSOP20E Packages L T3478/L T3478-1 4.5A, 42V , 2.5MHz High Current LED Driver with 3000:1 Dimming VIN: 2.8V to 36V , VOUT(MAX) = 42V , T rue Color PWM Dimming = 3000:1, ISD < 3μA, TSSOP16E Package L T3486 Dual 1.3A, 2MHz High Current LED Driver V IN: 2.5V to 24V , VOUT(MAX) = 36V , T rue Color PWM Dimming = 1000:1, ISD < 1μA, 5mm × 3mm DFN and TSSOP-16E Packages L T3496 45V , 2.1MHz 3-Channel (I LED = 1A) Full Featured LED Driver VIN: 3V to 30V (40VMAX), VOUT(MAX) = 45V , T rue Color PWM Dimming = 3000:1, ISD < 1μA, 4mm × 3mm QFN-28 Package L T3497 Dual 2.3MHz, Full Function LED Driver with Integrated Schottkys and 250:1 T rue Color PWM Dimming VIN: 2.5V to 10V , VOUT(MAX) = 32V , IQ = 6mA, ISD < 12μA, 2mm × 3mm L T3498 2.3MHz, 20mA LED Driver and OLED Driver with Integrated Schottky VIN: 2.5V to 12V , VOUT(MAX) = 32V , IQ = 1.65mA, ISD < 9μA, 2mm × 3mm L T3518/L T3517 2.3A/1.3A 45V , 2.5MHz Full Featured LED Driver with T rue Color PWM Dimming VIN: 3V to 30V (40VMAX), VOUT(MAX) = 42V , T rue Color PWM Dimming = 3000:1, ISD < 5μA, 4mm × 4mm QFN-16 Package L T3590 48V , 850kHz 50mA Buck Mode LED Driver V IN: 4.5V to 55V , Dimming = 200:1 T rue Color PWM, ISD < 15μA, 2mm × 2mm DFN-6 and SC70 Packages L T3592 36V , 2.2MHz, 500mA Buck Mode LED Driver VIN: 3.6V to 36V , T rue Color PWM Dimming = 10:1, ISD < 1μA, 2mm × 3mm DFN-10 and MSOP-10E Packages L T3595 45V , 2.5MHz 16-Channel Full Featured LED Driver V IN: 4.5V to 55V , VOUT(MAX) = 45V , T rue Color PWM Dimming = 5000:1, ISD < 1μA, 5mm × 9mm QFN-56 Package 90% Effi cient LED Driver for 60 White LEDs LED Current Matching vs Temperature TOTAL LED CURRENT (mA) EFFICIENCY (%) 20 40 80 60 100 100 120

3598 TA05b

VIN = 25V VIN = 16V