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Technical content

FEATURES

APPLICATIONS

DESCRIPTION

with 2.3A Switch Current The L T®3518 is a current mode DC/DC converter with an internal 2.3A, 45V switch speciﬁ cally designed to drive LEDs. The L T3518 operates as a LED driver in boost, buck mode and buck-boost mode. It combines a traditional voltage loop and a unique current loop to operate as a constant-current source or constant-voltage source. Pro- grammable switching frequency allows optimization of the external components for efﬁ ciency or component size. The switching frequency of the L T3518 can be synchronized to an external clock signal. The LED current is externally programmable with a 100mV sense resistor . The external PWM input provides 3000:1 LED dimming. The CTRL pin provides further 10:1 dimming ratio. The L T3518 is available in the tiny footprint 16-Lead QFN (4mm × 4mm) and the 16-Pin TSSOP package. The L T3518 provides a complete solution for both constant-voltage and constant-current applications. n 3000:1 T rue Color PWM™ Dimming Ratio n 2.3A, 45V Internal Switch n 100mV High Side Current Sense n Open LED Protection n Adjustable Frequency: 250kHz to 2.5MHz n Wide Input Voltage Range: Operation from 3V to 30V T ransient Protection to 40V n Operates in Boost, Buck Mode and Buck-Boost Mode n Gate Driver for PMOS LED Disconnect* n Constant-Current and Constant-Voltage Regulation n CTRL Pin Provides 10:1 Analog Dimming n Low Shutdown Current: <1μA n Available in (4mm × 4mm) 16-Lead QFN and 16-Pin TSSOP Packages n Display Backlighting n Automotive and Avionic Lighting n Illumination n Scanners 1.5A Buck Mode LED Driver Efﬁ ciency L, L T , L TC and L TM are registered trademarks of Linear Technology Corporation. T rue Color PWM is a trademark of Linear Technology Corporation. Patent Pending. All other trademarks are the property of their respective owners. *Patents Pending. 1.5A 10μF 15μH 2.2μF 0.1μF 68mΩ M1 2.2μF VREF ISP TGEN GNDVREF VC 16.9k 1MHz

3518 TA01a

0.1μF VIN SHDN CTRL PWM SYNC FB SS R T SW PVIN 24V VIN 3.3V ISN L T3518 TG PWM PWM DUTY CYCLE (%) EFFICIENCY (%) 100 20 40 60 80

3518 TA01b

CTRL = VREF

V Operating Junction Temperature Range (Notes 2, 4) (Note 1) 16 15 14 13 5 6 7 8 TOP VIEW UF PACKAGE 16-LEAD (4mm × 4mm) PLASTIC QFN 1 SW SW V IN SHDN FB VC CTRL PWM TG ISP ISN TGEN V REF RT SYNC SS TJMAX = 125°C, θJA = 36°C/W EXPOSED PAD (PIN 17) IS GND, MUST BE SOLDERED TO PCB FE PACKAGE 16-LEAD PLASTIC TSSOP TOP VIEW V IN SHDN VREF RT SYNC SS PWM CTRL SW SW TG ISP ISN TGEN FB V C GND TJMAX = 150°C, θJA = 40°C/W , θJC(PAD) = 10°C/W PIN CONFIGURATION ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL PART MARKING * PACKAGE DESCRIPTION TEMPERATURE RANGE L T3518EUF#PBF L T3518EUF#TRPBF 3518 16-Lead (4mm × 4mm) Plastic QFN –40°C to 125°C L T3518IUF#PBF L T3518IUF#TRPBF 3518 16-Lead (4mm × 4mm) Plastic QFN –40°C to 125°C L T3518EFE#PBF L T3518EFE#TRPBF 3518FE 16-Lead Plastic TSSOP –40°C to 125°C L T3518IFE#PBF L T3518IFE#TRPBF 3518FE 16-Lead Plastic TSSOP –40°C to 125°C L T3518HFE#PBF L T3518HFE#TRPBF 3518HFE 16-Lead Plastic TSSOP –40°C to 150°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/ Storage Temperature Range Lead Temperature (Soldering, 10 sec)

ELECTRICAL CHARACTERISTICS The l denotes the speciﬁ cations which apply over the full operating temperature range, otherwise speciﬁ cations are at TA = 25°C. (Note 2) VIN = 5V , SHDN = 5V , PWM = 5V unless otherwise noted. PARAMETER CONDITIONS MIN TYP MAX UNITS Minimum VIN Operating Voltage 3V Maximum VIN Operating Voltage Continuous Operation (Note 3) 30 V Current Sense Voltage (VISP – VISN)V CTRL = 2V , VISP = 24V , VC = 1V VCTRL = 2V , VISP = 0V , VC = 1V l 96 100 100 103 mV mV 10% Scale Current Sense Voltage (VISP – VISN)V CTRL = 100mV , VISP = 24V , VC = 1V 9 mV Current Sense Voltage Line Regulation 2V < V ISP < 45V 0.03 %/V VIN Supply Current PWM > 1.5V , V C = 0V PWM = 0V SHDN = 0V 4.5 0.1 mA mA μA Switching Frequency R T = 16.7k RT = 4.03k RT = 91.5k l 0.85 2.25 220 1.0 2.5 250 1.15 2.7 270 MHz MHz kHz R T Voltage 1V Soft-Start Pin Current SS = 0.5V , Out of Pin 6 9 12 μA SYNC Pull-Down Current (Into the Pin) V SYNC = 2V 60 μA SYNC Input Low 0.4 V SYNC Input High 1.5 V Maximum Duty Cycle R T = 91.5k (250kHz) SYNC = 300kHz Clock Signal, RT = 91.5k RT = 16.7k (1MHz) RT = 4.03k (2.5MHz) l Switch Current Limit 2.3 2.8 3.5 A Switch V CESAT ISW = 1.5A 400 mV Switch Leakage Current V SW = 45V , PWM = 0V 2 μA CTRL Input Bias Current Current Out of Pin, V CTRL = 0.1V 20 100 nA Error Ampliﬁ er T ransconductance 550 μS VC Output Impedance 1000 kΩ VC Idle Input Bias Current PWM = 0, V C = 1V –20 0 20 nA FB Pin Input Bias Current Current Out of Pin, V FB = 0.5V 20 100 nA FB Pin Threshold l 0.98 1.01 1.04 V ISP , ISN Idle Input Bias Current PWM = 0V 300 nA ISP , ISN Full-Scale Input Bias Current ISP Tied to ISN, V ISP = 24V , VCTRL = 2V 20 μA SHDN Voltage High 1.5 V SHDN Voltage Low 0.4 V SHDN Pin Bias Current 60 100 μA PWM Input High Voltage 1.5 V PWM Input Low Voltage 0.4 V PWM Pin Bias Current 60 120 μA TGEN Input High Voltage 1.5 V TGEN Input Low Voltage 0.4 V TGEN Pin Bias Current TGEN = 5V 100 200 μA VREF Pin Voltage I REF = –100μA l 1.96 2 2.04 V

ELECTRICAL CHARACTERISTICS The l denotes the speciﬁ cations which apply over the full operating temperature range, otherwise speciﬁ cations are at TA = 25°C. (Note 2) VIN = 5V , SHDN = 5V , PWM = 5V unless otherwise noted. 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 T3518E 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 T3518I is guaranteed over the full –40°C to 125°C operating junction temperature range. The L T3518H is guaranteed over the full –40°C to 150°C operating junction temperature range. Operating lifetime is derated at junction temperatures greater than 125°C. Note 3: Absolute maximum voltage at VIN, SHDN, PWM and TGEN pins is 40V for nonrepetitive 1 second transients and 30V for continuous operation. Note 4: 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 impair device reliability. PARAMETER CONDITIONS MIN TYP MAX UNITS V REF Pin Voltage Line Regulation 3V < V IN < 40V 0.03 %/V Gate Turn-On Delay C LOAD = 1nF Between ISP and TG 200 ns Gate Turn-Off Delay C LOAD = 1nF Between ISP and TG 200 ns Top Gate Drive VGS (VISP – VTG)V ISP = 24V , TGEN = 5V PWM = 0V 0 0.3 V V

TYPICAL PERFORMANCE CHARACTERISTICS VISP – VISN Threshold vs VCTRL Switch Current Limit vs Duty Cycle Oscillator Frequency vs RT VISP – VISN Threshold vs Temperature Switch Current Limit vs Temperature Oscillator Frequency vs Temperature VCTRL (V) VISP – VISN THRESHOLD (mV) 0.4 0.8 1.2 1.6

3518 G01

0.2 0.6 1.0 1.4 VIN = 5V VISP = 24V VC = 1V TA = 25°C DUTY CYCLE (%) CURRENT LIMIT (A) 0.5 1.0 1.5 2.0 2.5 3.0 20 40 60 80

3518 G02

TA = 25°C RT (kΩ)

100 OSCILLATOR FREQUENCY (kHz)

3518 G03

TA = 25°C VISP (V) VISP – VISN THRESHOLD (mV) 101 103 105

3518 G04

VCTRL = 2V VIN = 5V TA = 25°C VC = 1V TEMPERATURE (°C) –40 –15 2.0 CURRENT LIMIT (A) 2.4 3.0 –10 60 85

3518 G05

2.2 2.8 2.6 35 110 135 160 VIN = 5V TEMPERATURE (°C) –40 –20 1.5 OSCILLATOR FREQUENCY (MHz) 1.9 2.5 0 40 60

3518 G06

1.7 2.3 2.1 20 80 160100 120 140 VIN = 5V RT = 6.04k

TYPICAL PERFORMANCE CHARACTERISTICS FB Pin Threshold vs Temperature PMOS Turn-On PMOS Turn-Off TEMPERATURE (°C) –40

0.98 FB PIN THRESHOLD (V)

1.00 0.99 1.01 1.03 1.02 1.04 –20 0 20 40

3518 G10

VIN = 5V PWM 40V TG 30V 200ns/DIVVISP = 40V

3518 G11

200ns/DIVVISP = 40V

3518 G12

VISP – VISN Threshold vs VISP VISP (V) VISP – VISN THRESHOLD (mV) 101 103 105

3518 G07

VCTRL = 2V VIN = 5V TA = 25°C VC = 1V TEMPERATURE (°C) –40

1.98 VREF (V)

1.99 2.00 2.01 2.02 –20 0 20 40

3518 G08

VIN = 5V VIN (V) VIN CURRENT (mA)

3518 G09

TA = 25°C VC = 0V

SW: Switch Pin. Minimize trace at this pin to reduce EMI. VIN: Input Supply Pin. Must be locally bypassed. SHDN: Shutdown Pin. Tie to 1.5V or higher to enable device or 0.4V or less to disable device. VREF: Reference Output Pin. This pin can supply up to 100μA. RT: Switching Frequency Adjustment Pin. Set switching frequency using a resistor to GND (see Typical Performance Characteristics for values). For SYNC function, choose the resistor to program a frequency 20% slower than the SYNC pulse frequency. Do not leave this pin open. SYNC: Frequency Synchronization Pin. Tie an external clock signal here. R T resistor should be chosen to pro- gram a switching frequency 20% slower than SYNC pulse frequency. Synchronization (power switch turn-on) occurs a ﬁ xed delay after the rising edge of SYNC. Tie the SYNC pin to ground if this feature is not used. SS: Soft-Start Pin. Place a soft-start capacitor here. Leave the pin open if not in use. PWM: Pulse Width Modulated Input Pin. Signal low turns off channel, disables the main switch and makes the TG pin high. Tie the PWM pin to SHDN pin if not used. There is an equivalent 50k resistor from PWM pin to ground internally. CTRL: LED Current Adjustment Pin. Sets voltage across sense resistor between ISP and ISN. Connect directly to V REF for full-scale threshold of 100mV , or use signal values between GND and 1V to modulate LED current. Tie the CTRL pin to the V REF pin if not used. VC: gm Error Ampliﬁ er Output Pin. Stabilize the loop with an RC network or compensating C. FB: Voltage Loop Feedback Pin. Works as overvoltage protection for LED drivers. If FB is higher than 1V , the main switch is turned off. TGEN: Top Gate Enable Input Pin. Tie to 1.5V or higher to enable the PMOS driver function. Tie the TGEN pin to ground if TG function is not used. There is an equivalent 40k resistor from TGEN pin to ground internally. ISN: Current Sense (–) Pin. The inverting input to the current sense ampliﬁ er . ISP: Current Sense (+) Pin. The noninverting input to the current sense ampliﬁ er . Also serves as positive rail for TG pin driver . TG: Top Gate Driver Output. An inverted PWM sig- nal drives series PMOS device between V ISP and (VISP – 7V). An internal 7V clamp protects the VISP PMOS gate. Leave TG unconnected if not used. Ground: Exposed Pad. Solder paddle directly to ground plane.

Figure 1. Buck Mode LED Driver

3518 F01

The L T3518 is a constant frequency, current mode regula- tor with an internal power switch. Operation can be best understood by referring to the Block Diagram in Figure 1. At the start of each oscillator cycle, the SR latch is set, which turns on the Q1 power switch. A voltage proportional to the switch current is added to a stabilizing ramp and the resulting sum is fed into the positive terminal of the PWM comparator , A4. When this voltage exceeds the level at the negative input of A4, the SR latch is reset, turning off the power switch. The level at the negative input of A4 is set by the error ampliﬁ er A3. A3 has two inputs, one from the voltage feedback loop and the other one from the current loop. Whichever feedback input is lower takes precedence, and forces the converter into either constant-current or constant-voltage mode. The L T3518 is designed to transi- tion cleanly between these two modes of operation. The current sense ampliﬁ er senses the voltage across R SENSE and provides a pre-gain to ampliﬁ er A1. The output of A1 is simply an ampliﬁ ed version of the difference between the voltage across R SENSE and the lower of V CTRL/10 or 100mV . In this manner , the error ampliﬁ er sets the correct peak switch current level to regulate the current through RSENSE. If the error ampliﬁ er’s output increases, more current is delivered to the output; if it decreases, less current is delivered. The current regulated in R SENSE can be adjusted by changing the input voltage V CTRL. The current sense ampliﬁ er provides rail-to-rail current sense operation. The FB voltage loop is implemented by the ampliﬁ er A2. When the voltage loop dominates, the error ampliﬁ er and the ampliﬁ er A2 regulate the FB pin to 1.01V (constant-voltage mode). Dimming of the LED array 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 charge state of the VC pin will be saved on the external compensation capacitor . This feature reduces transient recovery time. When the PWM input again transitions high, the demand current for the switch returns to the value just before PWM last transitioned low. To further reduce transient recovery time, an external PMOS is used to disconnect the LED array current loop when PWM is low, stopping C FIL T from discharging.

There are two methods to control the current source for dimming using the L T3518. The ﬁ rst method uses the PWM pin to modulate the current source between zero and full current to achieve a precisely programmed aver- age current. To make this method of current control more accurate, the switch demand current is stored on the V C node during the quiescent phase. This feature minimizes recovery time when the PWM signal goes high. To further improve the recovery time, a disconnect switch is used in the LED current path to prevent the output capacitor from discharging in the PWM signal low phase. The minimum PWM on or off time will depend on the choice of operating frequency through R T input pin or SYNC pin. When using the SYNC function, the SYNC and PWM signals must have the aligned rising edges to achieve the optimized high PWM dimming ratio. For best current accuracy, the minimum PWM low or high time should be at least six switching cycles (3μs for f SW = 2MHz). Maximum PWM period is determined by the system and is unlikely to be longer than 12ms. The maximum PWM dimming ratio (PWM RATIO) can be calculated from the maximum PWM period (tMAX) and the minimum PWM pulse width (tMIN) as follows: PWMRATIO = tMAX tMIN (1) Example: tMAX = 9ms, tMIN = 3μs (fSW = 2MHz) PWMRATIO = 9ms/3μs = 3000:1 The second method of dimming control uses the CTRL pin to linearly adjust the current sense threshold during the PWM high state. When the CTRL pin voltage is less than 1V , the LED current is: ILED = VCTRL 10 RSENSE (2) Figure 2 Figure 3 APPLICATIONS INFORMATION When VCTRL is higher than 1V , the LED current is clamped to be: ILED = 100mV RSENSE (3) The LED current programming feature possibly increases 49.9k

3518 F02

45.3k 2VVREF PTC CTRL total dimming range by a factor of ten. The CTRL pin should not be left open (tie to V REF if not used). The CTRL pin can also be used in conjunction with a PTC thermistor to provide overtemperature protection for the LED load. Setting Output Voltage For a boost application, the output voltage can be set by selecting the values of R1 and R2 (see Figure 3) according to the following equation: VOUT = R1 R2 + 1 1.01V (4) L T3518 FB VOUT

3518 F03

3518 F04

ripple current “ΔI” of ~30% to 40% of the LED current. voltage to the converter , and tSW is the switching period. Table 1 provides some recommended inductor vendors. Table 1. Inductor Manufacturers ceramic capacitor is usually the best choice. capacitor is usually sufﬁ cient. and converter conﬁ guration, i.e., step-up or step-down. sized to attenuate the current ripple. the LED voltage during PWM transitions.

to get the required capacitance at the operation voltage. Table 2. Ceramic Capacitor Manufacturers ampliﬁ er whose VC output compensates the control loop. sation resistor and capacitor determine the loop stability. of LED current during fast transients on VIN or CTRL. recommended component vendors. Table 3. Schottky Diodes

tor values and corresponding switching frequencies. Table 4. Switching Frequency vs RT external clock when external clock is absent.

Buck Mode 1.5A LED Driver 1000:1 PWM Dimming at 120Hz 500mA, 5V to 12V Boost Converter with Accurate Input Current Limit Efﬁ ciency 1.5A 10μF 15μH 2.2μF 0.1μF RSENSE 68mΩ M1 2.2μF ISP TGEN GNDVREF VC RT 16.9k 1MHz

3518 TA02a

0.1μF C1: KEMET C0805C225K4RAC C2: MURATA GRM31MR71E225KA93 C3: MURATA GRM32DR71E106KA12B C4, C5: MURATA GRM21BR71H104KA01B D1: ZETEX ZLLS2000TA L1: TOKO B992AS-150M LEDS: LUXEON K2 (WHITE) M1: ZETEX ZXMP6A13GTA V IN SHDN CTRL PWM SYNC FB SS R T SW PVIN 24V VIN 3.3V ISN L T3518 TG PWM VREF PWM 5V/DIV ILED 1A/DIV IL 1A/DIV 2μs/DIVPVIN = 24V fOSC = 1MHz ILED = 1.5A

3518 TA02b

V REF FB VOUT 12V 500mA VIN SYNC 549k 10MF 0.1MFC4 10nF SHDN RT ISN L T3518 TGISP 49.9k RT 6.04k 2MHz 10k

3518 TA03a

2.2MF 4.3MH R SENSE 50m7 C1: KEMET C0805C225K4RAC C2: KEMET C1206C106K4RAC C3: MURATA GRM21BR71H104KA01B C4: MURATA GCM033R71A103KA03 D1: ZETEX ZLLS2000TA L1: TOKO B992AS-4R3N ILOAD (mA) EFFICIENCY (%) 400

3518 TA03b

3000:1 PWM Dimming at 120Hz Efﬁ ciency Buck-Boost Mode LED Driver 4.3μH RSENSE 330mΩ SHDN VC GNDRT SS RT 6.04k 2MHz

3518 TA04a

0.1μF 4.7μF 3.92M 124k 0.22μF 2.2μF 0.1μF PWM ISP FB ISN TG TGEN VREF CTRL SYNC 300mA VIN 8V TO 16V VIN L T3518 SW PWM C1: KEMET C0806C225K4RAC C2: KEMET C1206C475K3RAC C3, C4: MURATA GRM21BR71H104KA01B C5: MURATA GRM21BR71H224KA01B D1: ZETEX ZLLS2000TA L1: TOKO B992AS-4R3N LEDS: LUXEON I (WHITE) M1: ZETEX ZXMP6A13GTA PWM 5V/DIV ILED 200mA/DIV IL1 1A/DIV 500ns/DIVVIN = 10V fOSC = 2MHz ILED = 300mA

3518 TA04b

PWM DUTY CYCLE (%)

3518 TA04c

EFFICIENCY (%) VIN = 10V CTRL = VREF

1000:1 PWM Dimming at 120Hz Efﬁ ciency Buck Mode 1A LED Driver with Open LED Protection and Sync Input LED1 LED6 10μF 49.9k 2.00k FB 5.62k 10μH FB 2.2μF 0.1μF RSENSE 100mΩ M1 2.2μF VREF ISP TGEN GNDVREF VC RT 16.7k 1MHz

3518 TA05a

0.1μF V IN SHDN CTRL PWM SYNC FB SS R T SW PVIN 32V VIN 3.3V ISN L T3518 TG PWM SYNC 3.3V , 1.2MHz C1: KEMET C0806C225K4RAC C2: MURATA GRM31MR71E225KA93 C3: MURATA GRM32DR71E106KA12B C4, C5: MURATA GRM21BR71H104KA01B D1: ZETEX ZLLS2000TA L1: TOKO B992AS-100M LEDS: LUXEON III (WHITE) M1: ZETEX ZXMP6A13GTA M2: PHILIPS PMBT3906 PWM 5V/DIV ILED 1A/DIV IL1 1A/DIV 2μs/DIVPVIN = 32V fOSC = 1.2MHz ILED = 1A

3518 TA05b

PWM DUTY CYCLE (%) EFFICIENCY (%) 100 20 40 60 80

3518 TA05c

CTRL = VREF

Boost 300mA LED Driver with LED Open Protection 3000:1 PWM Dimming at 100Hz Efﬁ ciency LED1 LED2 LED8 8.2μH RSENSE 330mΩ 30.1k SHDN VC GNDRT SS RT 16.9k 1MHz

3518 TA06a

0.1μF 6.8μF 2.2μF 0.1μF PWM ISP ISN TG FB TGEN VREF CTRL SYNC 300mA VIN 8V TO 16V VIN L T3518 SW PWM C1: KEMET C1206C225K2RAC C2: TDK C5750X7R1H685M C3, C4: MURATA GRM21BR71H104KA01B D1: ZETEX ZLLS2000TA L1: TOKO B992AS-8R2N LEDS: LUXEON I (WHITE) M1: ZETEX ZXMP6A13GTA PWM 5V/DIV ILED 200mA/DIV IL1 1A/DIV 1μs/DIVVIN = 12V fOSC = 1MHz ILED = 300mA

3518 TA06b

PWM DUTY CYCLE (%) EFFICIENCY (%) 100

3518 TA06c

VIN = 12V CTRL = VREF

16-Lead Plastic QFN (4mm × 4mm) (Reference L TC DWG # 05-08-1692) 4.00 ± 0.10 (4 SIDES) NOTE: 1. DRAWING CONFORMS TO JEDEC PACKAGE OUTLINE MO-220 VARIATION (WGGC) 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 PIN 1 TOP MARK (NOTE 6) 0.55 ± 0.20 1615 BOTTOM VIEW—EXPOSED PAD 2.15 ± 0.10 (4-SIDES) 0.75 ± 0.05 R = 0.115 TYP 0.30 ± 0.05

0.65 BSC

0.200 REF

0.00 – 0.05 (UF16) QFN 1004 RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS 0.72 ±0.05 0.30 ±0.05 2.15 ± 0.05 (4 SIDES)2.90 ± 0.05 4.35 ± 0.05 PACKAGE OUTLINE PIN 1 NOTCH R = 0.20 TYP OR 0.35 × 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. 16-Lead Plastic TSSOP (Reference L TC DWG # 05-08-1663) PACKAGE DESCRIPTION FE16 (BA) TSSOP 0204 0.09 – 0.20 (.0035 – .0079) 0° – 8° 0.25 REF 0.50 – 0.75 (.020 – .030) 4.30 – 4.50* (.169 – .177) 13 4 5 6 7 8 10 9 4.90 – 5.10* (.193 – .201) 16 1514 13 12 11 1.10 (.0433) MAX 0.05 – 0.15 (.002 – .006) 0.65 (.0256) BSC 2.74 (.108) 2.74 (.108) 0.195 – 0.30 (.0077 – .0118) TYP MILLIMETERS (INCHES) *DIMENSIONS DO NOT INCLUDE MOLD FLASH. MOLD FLASH SHALL NOT EXCEED 0.150mm (.006") PER SIDE NOTE: 1. CONTROLLING DIMENSION: MILLIMETERS 2. DIMENSIONS ARE IN RECOMMENDED SOLDER PAD LAYOUT 3. DRAWING NOT TO SCALE 0.45 ±0.05 4.50 ±0.10 6.60 ±0.10 1.05 ±0.10 2.74 (.108) 2.74 (.108) SEE NOTE 4 4. RECOMMENDED MINIMUM PCB METAL SIZE FOR EXPOSED PAD ATTACHMENT 6.40 (.252) BSC

Linear Technology Corporation 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com © LINEAR TECHNOLOGY CORPORATION 2007 LT 0308 REV B • PRINTED IN USA TYPICAL APPLICATION 5.5V SEPIC Converter with Short-Circuit Protection Efﬁ ciency SW VC GND SS CTRL SYNC SHDN TGEN V REF FB TG ISP ISN RT VOUT 5.5V 500mA VIN 221k 10μF 10μF 0.1μFC4 10nF SHDN PWM L T3518 VIN 49.9k RT 6.04k 2MHz 10k

3518 TA07a

2.2μF 2.4μH 2.4μH R SENSE 0.15Ω C1: KEMET C0805C225K4RAC C2, C5: KEMET C1206C106K4RAC C3: MURATA GRM21BR71H104KA01B C4: MURATA GCM033R71A103KA03 D1: ZETEX ZLLS2000TA L1, L2: TOKO 962BS-2R4M I LOAD (mA) 100 400

3518 TA07b

EFFICIENCY (%) PART NUMBER DESCRIPTION COMMENTS L T1618 Constant Current, 1.4MHz, 1.5A Boost Converter V IN: 5V to 18V , VOUT(MAX) = 36V , Dimming = Analog/PWM, ISD < 1μA, L T3003 3-Channel LED Ballaster with PWM Dimming V IN: 3V to 48V , Dimming = 3000:1 T rue Color PWM, ISD < 5μA, L T3474 36V , 1A (I LED), 2MHz, Step-Down LED Driver V IN: 4V to 36V , VOUT(MAX) = 13.5V , Dimming = 400:1 T rue Color PWM, ISD < 1μA, TSSOP16E Package L T3475 Dual 1.5A (I LED), 36V 2MHz Step-Down LED Driver V IN: 4V to 36V , VOUT(MAX) = 13.5V , Dimming = 3000:1 T rue Color PWM, ISD < 1μA, TSSOP20E Package L T3476 Quad Output 1.5A, 36V , 2MHz High Current LED Driver with 1,000:1 Dimming VIN: 2.8V to 16V , VOUT(MAX) = 36V , Dimming = 1000:1 T rue Color PWM, ISD < 10μA, 5mm × 7mm QFN 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, TSSOP20E Packages L T3478/L T3478-1 4.5A, 42V , 2.5MHz High Current LED Driver with 3,000:1 Dimming VIN: 2.8V to 36V , VOUT(MAX) = 42V , Dimming = 3000:1 T rue Color PWM, ISD < 3μA, TSSOP16E Packages L T3479 3A, Full Featured DC/DC Converter with Soft-Start and Inrush Current Protection VIN: 2.5V to 24V , VOUT(MAX) = 40V , IQ = 6.5mA, ISD < 1μA, DFN and TSSOP Packages L T3486 Dual 1.3A, 2MHz High Current LED Driver V IN: 2.5V to 24V , VOUT(MAX) = 36V , Dimming = 1000:1 T rue Color PWM, ISD < 1μA, 5mm × 3mm DFN, TSSOP16E L T3496 T riple Output LED Driver V IN: 3V to 40V , VOUT(MAX) = 45V , Dimming = 3000:1 T rue Color PWM, ISD < 10μA, 4mm × 5mm QFN Package L T3517 Full-Featured LED Driver with 1.5A Switch Current V IN: 3V to 40V , VOUT(MAX) = 45V , Dimming = 5000:1 T rue Color PWM, ISD < 1μA, 4mm × 4mm QFN and TSSOP Packages L T3590 48V Buck Mode 50mA LED Driver V IN: 4.5V to 55V , Drives Up to 10 LEDs, 200:1 Dimming, ISO = 15mA, 2mm × 2mm DFN SC70 L T3595 16 Channel Buck LED Driver Mode V IN: 4.5V to 45V , Drives Up to 160 LEDs, 5000:1 Dimming, 5mm × 9mm QFN LT C®3783 High Current LED Controller V IN: 3V to 36V , VOUT(MAX) = Ext FET , Dimming = 3000:1 T rue Color PWM, ISD < 20μA, 5mm × 4mm QFN10, TSSOP16E Packages RELATED PARTS

Selected Specification

Linear Technology 3518FE overview.

Summary

Full-Featured LED Driver with 2.3A Switch Current

Description

Full-Featured LED Driver with 2.3A Switch Current

Source title 3518FE Datasheet(PDF) - Linear Technology

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