LT3590ESC8-TRPBF

FEATURES ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ LT3590 48V Buck Mode LED Driver in SC70 and 2mm x 2mm DFN DESCRIPTION The LT®3590 is a fixed frequency buck mode converter specifically designed to drive up to 10 LEDs in series from a 48V DC source. Series connection of the LEDs provides identical LED currents of up to 50mA, resulting in uniform brightness and eliminating the need for ballast resistors. A fixed frequency, current mode architecture results in stable operation over a wide range of input voltage and output voltage. The high switching frequency of 850kHz permits the use of tiny, low profile inductors and capacitors. A single pin performs both shutdown and accurate LED dimming control. The power switch, Schottky diode and control circuitry are all contained inside a space saving SC70 package or 2mm × 2mm DFN package to allow a small converter footprint and lower parts cost. , LT, LTC and LTM are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. 4.5V to 55V Input Voltage Range Up to 50mA LED Current 80mA, 55V Switch Internal Schottky Diode 15μA Supply Current in Shutdown 500μA Supply Current Operating, Not Switching Switching Frequency: 850kHz 200mV Feedback Voltage with ±5% Accuracy CTRL Input Performs Dimming and Shutdown 91% Efficiency (10 LEDs, 50mA) Requires Only 1μF Output Capacitor 8-Lead SC70 Package 6-Lead 2mm × 2mm DFN Package APPLICATIONS ■ ■ ■ LED Fixed Signage Traffic Signs Neon Sign Replacement TYPICAL APPLICATION Buck Mode Driver for Ten White LEDs 1μF 50mA 4Ω VIN 48V 1μF CONTROL VIN CTRL LT3590 VREG 0.1μF GND SW 50 3590 TA01a Conversion Efficiency 100 90 EFFICIENCY (%) 80 70 60 LED 470μH 40 0 10 20 30 LED CURRENT (mA) 40 50 3590 TA01b 3590f 1 LT3590 ABSOLUTE MAXIMUM RATINGS (Note 1) Input Voltage (VIN) ..................................... –0.3V to 55V LED Voltage ............................................... –0.3V to 55V CTRL Voltage ................................................. 0V to 6.0V VREG Voltage ................................................. 0V to 4.0V Operating Junction Temperature Range (Note 2) ...............................................– 40°C to 85°C Maximum Junction Temperature........................... 125°C Storage Temperature Range...................– 65°C to 150°C Lead Temperature (Soldering, 10 sec) SC 8 Package Only ............................................ 300°C PIN CONFIGURATION TOP VIEW CTRL 1 GND 2 SW 3 7 6 VREG 5 LED 4 VIN SW 1 GND 2 GND 3 GND 4 TOP VIEW 8 VIN 7 LED 6 VREG 5 CTRL DC PACKAGE 6-LEAD (2mm × 2mm) PLASTIC DFN TJMAX = 125°C, θJA = 65°C/W TO 85°C/W, θJC = 20°C/W EXPOSED PAD (PIN 7) IS GND, MUST BE SOLDERED TO PCB SC8 PACKAGE 8-LEAD PLASTIC SC70 TJMAX = 125°C, θJA = 75°C/W TO 95°C/W ORDER INFORMATION LEAD FREE FINISH LT3590EDC#PBF LT3590ESC8#PBF TAPE AND REEL LT3590EDC#TRPBF LT3590ESC8#TRPBF PART MARKING LCNZ LCPB PACKAGE DESCRIPTION 6-Lead (2mm × 2mm) Plastic DFN 8-Lead Plastic SC70 TEMPERATURE RANGE –40°C to 85°C –40°C to 85°C Consult LTC Marketing for parts specified with wider operating temperature ranges. Consult LTC Marketing for information on non-standard lead based finish parts. For more information on lead free part marking, go to: http://www.linear.com/leadfree/ For more information on tape and reel specifications, go to: http://www.linear.com/tapeandreel/ 3590f 2 LT3590 ELECTRICAL CHARACTERISTICS PARAMETER Minimum Operating Voltage LED Current Sense Voltage (VIN - VLED) Sense Voltage Load Regulation Quiescent Current ON, No Switching Quiescent Current in Shutdown Switching Frequency Maximum Duty Cycle Switch Current Limit Switch VCESAT Switch Leakage Current VCTRL for Full LED Current VCTRL to Shut Down IC VCTRL to Turn on IC CTRL Pin Bias Current LED Pin Bias Current LDO Voltage VREG LDO Load Regulation LDO Current Limit Schottky Forward Drop Schottky Leakage Current ISCHOTTKY = 50mA VR = 48V VCTRL = 1V, Current Out of Pin VLED = 47.8V IVREG = 1mA ΔIVREG = 0mA to 1mA 1.5 0.8 4 3.1 150 100 9 3.3 17 14 3.5 ISW = 50mA VSW = 48V ● ● The ● denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C, VIN = 48V, VCTRL = 3.3V, unless otherwise noted. CONDITIONS MIN 4.5 190 200 5 500 15 ● ● TYP MAX 210 700 20 1050 150 2 100 UNITS V mV mV μA μA kHz % mA mV μA V mV mV nA μA V mV mA V μA ΔILED = 10mA to 50mA VLED = 47.7V VCTRL = 0V 650 90 80 850 115 500 1 1.5 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 LT3590E is guaranteed to meet performance specifications from 0°C to 85°C junction temperature. Specifications over the –40°C to 85°C operating junction temperature range are assured by design, characterization and correlation with statistical process controls. 3590f 3 LT3590 TYPICAL PERFORMANCE CHARACTERISTICS Switch Saturation Voltage (VCESAT) 0.8 SWITCH SATURATION VOLTAGE (V) 0.7 –40°C 0.6 0.5 25°C 0.4 0.3 0.2 125°C SCHOTTKY FORWARD DROP (V) 1.2 1.1 1.0 0.9 0.8 0.7 0.6 0.5 0.4 20 60 40 80 SWITCH CURRENT (mA) 100 3590 G01 Schottky Forward Voltage Drop 20 Shutdown Quiescent Current vs VIN VCTRL = 0V TA = 25°C –40°C 25°C SHUTDOWN CURRENT (μA) 18 16 125°C 14 12 0 100 200 50 150 SCHOTTKY FORWARD CURRENT (mA) 3590 G02 10 0 10 20 30 VIN (V) 40 50 60 3590 G03 Shutdown Quiescent Current vs Temperature 20 VCTRL = 0V VIN = 48V QUIESCENT CURRENT (μA) 600 Quiescent Current 2.0 SCHOTTKY LEAKAGE CURRENT (μA) VCTRL = 3.3V TA = 25°C 550 Schottky Leakage Current SHUTDOWN CURRENT (μA) 18 1.5 VIN = 48V 1.0 VIN = 24V 0.5 VIN = 4.5V 0 –50 –25 0 75 50 25 TEMPERATURE (°C) 100 125 16 500 14 450 12 10 –50 –25 400 0 50 75 25 TEMPERATURE (°C) 100 125 0 10 20 30 VIN (V) 40 50 60 3590 G05 3590 G04 3590 G06 Switching Waveform IL 20mA/DIV CTRL 5V/DIV VSW 50V/DIV Transient Response VSW 20V/DIV IL 50mA/DIV ILED 50mA/DIV VIN = 48V ILED = 50mA 10 WHITE LEDs L = 470μH (COILCRAFT) 1μs/DIV 3590 G07 VIN = 48V ILED = 50mA 10 BLUE LEDs 40μs/DIV 3590 G08 3590f 4 LT3590 TYPICAL PERFORMANCE CHARACTERISTICS Sense Voltage (VIN – VLED) vs VCTRL 0.25 SWITCHING CURRENT LIMIT (mA) VIN = 48V ILED = 50mA TA = 25°C 150 140 130 120 110 100 90 80 0 0.5 1 VCTRL (V) 3590 G09 Switching Current Limit vs Duty Cycle TA = 25°C SWITCHING CURRENT LIMIT (mA) 150 140 130 120 110 100 90 Switching Current Limit vs Temperature SENSE VOLTAGE (VIN-VLED) 0.20 0.15 0.10 0.05 0 1.5 2 0 20 40 60 80 100 3590 G10 80 –50 –25 0 DUTY CYCLE (%) 75 50 25 TEMPERATURE (°C) 100 125 3590 G11 Sense Voltage (VIN – VLED) vs VIN 206 ILED = 50mA 10 WHITE LEDs 204 TA = 25°C VIN-VLED (mV) 202 200 198 196 194 0 10 20 30 VIN (V) 206 204 202 200 198 196 Sense Voltage (VIN – VLED) vs Temperature 1000 SWITCHING FREQUENCY (KHz) 950 900 850 800 750 Switching Frequency over Temperature VIN = 48V VIN-VLED (mV) 40 50 60 3590 G12 194 –50 –25 0 75 50 25 TEMPERATURE (°C) 100 125 700 –50 –25 0 50 75 25 TEMPERATURE (°C) 100 125 3590 G13 3590 G14 Internal Regulator Line Regulation 3.40 TA = 25°C 3.35 VREG (V) VREG (V) VCTRL = 0V ILOAD = 0V 3.35 3.40 Internal Regulator Load Regulation 3.40 TA = 25°C VCTRL = 0V ILED = 0V 3.35 TREG (V) Internal Regulator VREG vs Temperature VCTRL = 3.3V ILOAD = 1mA 3.30 VCTRL = 3.3V ILOAD = 1mA 3.25 3.30 VCTRL = 3.3V ILED = 50mA 3.25 3.30 3.25 3.20 0 10 20 30 VIN (V) 40 50 60 3590 G15 3.20 0 0.2 0.6 0.4 ILOAD (mA) 0.8 1 3590 G16 3.20 –50 –25 75 0 25 50 TEMPERATURE (°C) 100 125 3590 G17 3590f 5 LT3590 PIN FUNCTIONS (SC70/DFN) SW (Pin 1/Pin 3): Switch Pin. Minimize trace area at this pin to minimize EMI. Connect the inductor at this pin. GND (Pins 2, 3, 4/Pin 2): Ground Pins. All ground pins should be tied directly to local ground plane. Proper soldering of these pins to the PCB ground is required to achieve the rated thermal performance. CTRL (Pin 5/Pin 1): Dimming and Shutdown Pin. Connect it below 100mV to disable the switcher. As the pin voltage is ramped from 0V to 1.5V, the feedback voltage (VIN - VLED) ramps from 0mV to 200mV, controlling the LBD current. V − VLED ILED = IN R1 VREG (Pin 6/Pin 6): Internally Generated 3.3V Regulated Output Pin. Must be locally bypassed with a 0.1μF X5R capacitor. LED (Pin 7/Pin 5): Connection point for the anode of the highest LED and the sense resistor. VIN (Pin 8/Pin 4): Input Supply Pin. Must be locally bypassed. Exposed Pad (NA/Pin 7): Ground. The Exposed Pad should be soldered to the PCB ground to achieve the rated thermal performance. BLOCK DIAGRAM VIN 48V C1 1μF VIN R1 6.8Ω + EAMP REG VREG C3 0.1μF VREF 1.25V START-UP CONTROL ∑ RAMP GENERATOR 850kHz OSCILLATOR CTRL CONTROL 6 + – – – + + + PWM R S Q A = 6.25 LED C2 1μF – SW L1 470μH VOUT + ISNS – GND 3590 F01 Figure 1. Block Diagram 3590f LT3590 OPERATION The LT3590 uses a constant-frequency, current mode control scheme to provide excellent line and load regulation. Operation can be best understood by referring to the Block Diagram. At power-up, the bandgap reference, the start-up bias, and the regulator are turned on. If CTRL is pulled higher than 150mV, the switching converter sub-blocks including the oscillator, the PWM comparator and the error amplifier are also turned on. At the start of each oscillator cycle, the power switch Q1 is turned on. Current flows through the inductor and the switch to ground, ramping up as the switch stays on. 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. When this voltage exceeds the level at the negative input of the PWM comparator, the PWM logic turns off the power switch. The level at the negative input of the PWM comparator is set by the error amplifier EAMP and is simply , an amplified version of the difference between the VIN and VLED voltage and the bandgap reference. In this manner, the error amplifier sets the correct peak current level in inductor L1 to keep the output in regulation. The CTRL pin is used to adjust the reference voltage. The LT3590 enters into shutdown when CTRL is pulled lower than 100mV. Input Voltage Range The minimum input voltage required to generate a particular output voltage in an LT3590 application is limited by either its 4.5V limit or by its maximum duty cycle. The duty cycle is the fraction of time that the internal switch is on and is determined by the input and output voltages: DC = VLED + VD VIN – VSW + VD The maximum input voltage is limited by the absolute maximum VIN rating of 55V. Pulse-Skipping For LED strings with a low number of LEDs (1, 2, or 3), the LT3590 can drive currents without pulse-skipping as long as the voltage across the LED and sense resistor is greater than roughly 15% of the input supply voltage. If the LED voltage plus sense resistor is less than 15% of the input supply, the device will begin skipping pulses. This will result in some low frequency ripple, although the LED current remains regulated on an average basis down to zero. Discontinuous Current Mode The CTRL pin, in conjunction with the sense resistor, can be used to program the LED current as discussed under Applications Information. The LT3590 can drive a 10-LED string at 10mA LED current operating in continuous conduction mode, using the recommended external components shown in the front page application circuit with the sense resistor equal to 10Ω. As current is further reduced, the regulator enters discontinuous conduction mode. The photo in Figure 2 details circuit operation driving ten LEDs at 2mA load. During the discharge phase, the inductor current reaches zero. After the inductor current reaches zero, the SW pin exhibits ringing due to the LC tank circuit formed by the inductor in combination with the switch and the diode capacitance. This ringing is not harmful; far less spectral energy is contained in the ringing than in the switch transitions. The ringing can be damped by application of a 3kΩ resistor across the inductor, although this will degrade efficiency. VSW 20V/DIV Where VD is the forward voltage drop of the catch diode (~0.8V) and VSW is the voltage drop of the internal switch at maximum load (~0.5V). Given DCMAX = 0.9, this leads to minimum input voltage of: (V + V ) VIN(MIN) = LED D + VSW − VD DCMAX IL 10mA/DIV 400ns/DIV VIN = 48V ILED = 2mA 10 WHITE LEDs L = 470μH (MURATA) 3590 F02 Figure 2. Switching Waveforms 3590f 7 LT3590 APPLICATIONS INFORMATION Inductor Selection A 220μH inductor is recommended for most LT3590 applications with VIN < 25V and 470μH is recommended for applications with VIN > 25V. Although small size and high efficiency are major concerns, the inductor should have low core losses at 850kHz and low DCR (copper wire resistance). Several manufacturers and inductor series that meet these criteria are listed in Table 1. The efficiency comparison of different inductors is shown in Figure 3. Table 1. Inductor Manufacturers INDUCTANCE RANGE (μH) (RELEVANT TO THIS PART) 100 TO 680 100 TO 680 100 TO 330 100 TO 680 100 TO 390 100 TO 680 100 TO 270 100 TO 680 100 TO 220 100 to 470 100 to 330 100 to 560 100 to 680 5.2 × 5.8 × 4.5 7.0 × 7.8 × 5.0 2.5 × 3.2 × 2.2 3.2 × 2.5 × 2.0 4.5 × 3.2 × 2.0 Capacitor Selection The small size of ceramic capacitors make them ideal for LT3590 applications. X5R and X7R types are recommended because they retain their capacitance over wider voltage and temperature ranges than other types such as Y5V or Z5U. A 1μF input capacitor and a 0.1μF regulator capacitor are sufficient for most applications. For the output capacitor, 1μF is generally recommended, but if the voltage across the capacitor exceeds 10V, a 0.47μF capacitor may be used instead. For applications driving one or two LEDs a 2.2μF output capacitor is needed. Table 2 shows a list of several ceramic capacitor manufacturers. Consult the manufacturers for detailed information on their entire selection of ceramic parts. Table 2: Recommended Ceramic Capacitor Manufacturers Taiyo Yuden AVX Murata Kemet (408) 573-4150 www.t-yuden.com (803) 448-9411 www.avxcorp.com (714) 852-2001 www.murata.com (408) 986-0424 www.kemet.com VENDOR Coilcraft www.coilcraft.com PART SERIES DO1605 LPS4012 LPS3010 1812FS MSS5131 CDC4D20 LLQ1608 LLQ2012 WE-PD2 TYPE M WE-PD2 TYPE L CTX32C LQH32M LQH43M DIMENSIONS (mm) 5.4 × 4.2 × 1.8 4.0 × 4.0 × 1.2 3.0 × 3.0 × 0.9 5.1 × 5.1 × 3.1 4.8 × 4.8 × 2.0 Sumida www.sumida.com Toko www.tokoam.com Würth Elektronik www.we-online.com Coiltronics www.cooperet.com Murata www.murata.com 92 90 EFFICIENCY (%) VIN = 48V 10 LEDs FRONT PAGE APPLICATION CIRCUIT TDK SLF70145-471MR22-PF MURATA QH32CN471K23 MURATA LQH43CN471K03 COILCRAFT LP06013-474KLB COILCRAFT 1008PS-474KLB COILCRAFT LPS4012-474ML 88 86 84 0 10 30 20 LED CURRENT (mA) 40 50 3590 F03 Figure 3. Efficiency Comparison of Different Inductors 3590f 8 LT3590 APPLICATIONS INFORMATION Programming LED Current The feedback resistor (R1 in Figure 1) and the sense voltage (VIN - VLED) control the LED current. ILED = VIN − VLED R1 Using a DC Voltage For some applications, the preferred method of brightness control is a variable DC voltage to adjust the LED current. The CTRL pin voltage can be modulated to set the dimming of the LED string. As the voltage on the CTRL pin increases from 0V to 1.5V, the LED current increases from 0 to ILED. As the CTRL pin voltage increases beyond 1.5V, it has no effect on the LED current. The LED current can be set by: ILED = ILED 200mV , when VCTRL > 1.5V R1 V = CTRL ,when VCTRL < 1.25V 6.25 • R1 The CTRL pin controls the sense reference voltage as shown in the Typical Performance Characteristics. For CTRL higher than 1.5V, the sense reference is 200mV, which results in full LED current. In order to have accurate LED current, precision resistors are preferred (1% is recommended). The formula and table for R1 selection are shown below. 200mV R1 = ILED Table 3. R1 Theoretical Value for 200mV Sense ILED (mA) 10 20 30 40 50 R1 (Ω) 20 10 6.8 5.0 4.0 Feedback voltage variation versus control voltage is shown in Figure 4. Using a Filtered PWM Signal A variable duty cycle PWM can be used to control the brightness of the LED string. The PWM signal is filtered (Figure 5) by a RC network and fed to the CTRL pin. The corner frequency of R1, C1 should be much lower than the frequency of the PWM signal. R1 needs to be much smaller than the internal impedance in the CTRL pin which is 100kΩ. LT3590 R1 10k PWM kHz TYP CTRL C1 1μF 3590 F05 Dimming Control There are three different types of dimming control circuits. The LED current can be set by modulating the CTRL pin with a DC voltage, a filtered PWM signal or directly with a PWM signal. 0.25 0.20 VIN-VLED (V) 0.15 Figure 5. Dimming Control Using a Filtered PWM Signal 0.10 0.05 0 0 0.5 1.0 VCTRL (V) 1.5 2.0 3590 F04 Figure 4. Dimming and Shutdown Using CTRL Pin 3590f 9 LT3590 APPLICATIONS INFORMATION Direct PWM Dimming Changing the forward current flowing in the LEDs not only changes the intensity of the LEDs, it also changes the color. The chromaticity of the LEDs changes with the change in forward current. Many applications cannot tolerate any shift in the color of the LEDs. Controlling the intensity of the LEDs with a direct PWM signal allows dimming of the LEDs without changing the color. In addition, direct PWM dimming offers a wider dimming range to the user. Dimming the LEDs via a PWM signal essentially involves turning the LEDs on and off at the PWM frequency. The typical human eye has a limit of ~60 frames per second. By increasing the PWM frequency to ~80Hz or higher, the eye will interpret that the pulsed light source is continuously on. Additionally, by modulating the duty cycle (amount of “on-time”), the intensity of the LEDs can be controlled. The color of the LEDs remains unchanged in this scheme since the LED current value is either zero or a constant value. The time it takes for the LED current to reach its programmed value sets the achievable dimming range for a given PWM frequency. For example, the settling time of the LED current in Figure 6 is approximately 50μs for a 48V input voltage. The achievable dimming range for this application and 100Hz PWM frequency can be determined using the following method. Example: ƒ = 100Hz, t SETTLE = 50μs tPERIOD = 1 1 = = 0.01s ƒ 100 tPERIOD 0.01s = = 200 : 1 t SETTLE 50μs t SETTLE 50μs • 100 = • 100 = 0.5% 0 tPERIOD 0.01s Dim Range = Min Duty Cycle = Duty Cycle Range = 100% → 0.5% at 100Hz The calculations show that for a 100Hz signal the dimming range is 200 to 1. In addition, the minimum PWM duty cycle of 0.5% ensures that the LED current has enough time to settle to its final value. Figure 7 shows the dimming range achievable for three different frequencies with a settling time of 50μs. PWM 5V/DIV VSW 20V/DIV 100Hz 1kHz 10kHz ILED 20mA/DIV VIN = 48V 4 LEDs 2ms/DIV 3590 F06 1 10 100 1000 3590 F07 PWM DIMMING RANGE Figure 6. Direct PWM Dimming Waveforms Figure 7. Dimming Range Comparison of Three PWM Frequencies 3590f 10 LT3590 APPLICATIONS INFORMATION The dimming range can be further extended by changing the amplitude of the PWM signal. The height of the PWM signal sets the commanded sense voltage across the sense resistor through the CTRL pin. In this manner both analog dimming and direct PWM dimming extend the dimming range for a given application. The color of the LEDs no longer remains constant because the forward current of the LED changes with the height of the CTRL signal. For the ten LED application described above, the LEDs can be dimmed first, modulating the duty cycle of the PWM signal. Once the minimum duty cycle is reached, the height of the PWM signal can be decreased below 1.5V down to 150mV. The use of both techniques together allows the average LED current for the ten LED application to be varied from 50mA down to less than 50μA. Internal Voltage Regulator The LT3590 has a 3.3V onboard voltage regulator capable of sourcing up to 1mA of current for use by an external device. This feature may be used to power-up a controller from the LT3590. The 3.3V is available even during shutdown. It is required to place a 0.1μF capacitor from VREG to ground. The regulator current is limited to 1.5mA. Board Layout Considerations As with all switching regulators, careful attention must be paid to the PCB board layout and component placement. To prevent electromagnetic interference (EMI) problems, proper layout of high frequency switching paths is essential. Minimize the length and area of all traces connected to the switching node pin (SW). Keep the sense voltage pins (VIN and LED) away from the switching node. Place the output capacitor, C2, next to the VIN pin. Always use a ground plane under the switching regulator to minimize interplane coupling. Recommended component placement is shown in Figure 8. C3 VREG CTRL 5 6 7 8 VIN VIN C1 VREG CTRL 4 3 2 1 CTRL GND GND GND C3 GND VREG CTRL 1 2 3 C1 GND SW C2 7 6 5 4 VIN R1 LED VREG VIN R1 LED C2 OUT L1 L1 SW OUT 3590 F08 (a) SC70 Package (b) 2mm × 2mm DFN Package Figure 8. Recommended Component Placement 3590f 11 LT3590 TYPICAL APPLICATIONS 48V Supply for 6 LED String, 50mA Current C2 1μF R1 4Ω VIN 48V 6 LEDs VIN CTRL LT3590 VREG C3 0.1μF GND SW 3590 TA02a Conversion Efficiency 100 90 50mA EFFICIENCY (%) 80 70 60 50 40 C1 1μF LED L1 470μH CONTROL >1.5V 0 10 20 30 LED CURRENT (mA) 40 50 3590 TA02b L1: MURATA LQH32CN221K03 48V Supply for 5 LED String, 30mA Current C2 1μF R1 6.8Ω VIN 48V 30mA EFFICIENCY (%) 80 70 60 50 SW GND 3590 TA03a Conversion Efficiency 100 90 C1 1μF VIN CTRL LT3590 VREG LED L1 470μH CONTROL >1.5V C3 0.1μF 40 0 5 20 15 10 LED CURRENT (mA) 25 30 3590 TA03b L1: MURATA LQH32CN-391 24V Supply for a 5 LED String, 30mA Current C2 1μF R1 6.8Ω VIN 24V 30mA EFFICIENCY (%) 80 70 60 50 SW GND 3590 TA04a Conversion Efficiency 100 90 C1 1μF VIN CTRL LT3590 VREG LED L1 220μH CONTROL >1.5V C3 0.1μF 40 0 5 20 15 10 LED CURRENT (mA) 25 30 3590 TA04b L1: MURATA LQH32CN-221 3590f 12 LT3590 TYPICAL APPLICATIONS 12V or 24V Supply for a Single LED, 50mA Current C2 2.2μF R1 4Ω VIN 12V OR 24V 50mA EFFICIENCY (%) 80 75 70 65 24V 60 55 50 45 3590 TA05a Conversion Efficiency 12V C1 1μF VIN CTRL LT3590 VREG LED L1 220μH SW GND CONTROL >1.5V C3 0.1μF 40 0 10 20 30 LED CURRENT (mA) 40 50 3590 TA05b 48V Supply for Two Strings of 10 LEDs, 25mA Current C2 1μF R1 4Ω 25mA EFFECIENCY (%) 80 70 60 50 VIN CTRL LT3590 VREG C3 0.1μF GND SW LED L1 470μH 40 0 5 100 90 Conversion Efficiency 25mA VIN 48V C1 1μF CONTROL >1.5V 10 15 LED CURRENT (mA) 20 25 3590 TA06b 3590 TA06a 12V Supply for a 3 LED String, 50mA Current C2 1μF R1 4Ω VIN 12V 50mA EFFICIENCY (%) 80 70 60 50 SW GND 3590 TA07a Conversion Efficiency 100 90 C1 1μF VIN CTRL LT3590 VREG LED L1 220μH CONTROL >1.5V C3 0.1μF 40 0 10 20 30 LED CURRENT (mA) 40 50 3590 TA07b L1: MURATA LQH32CN-221 3590f 13 LT3590 PACKAGE DESCRIPTION DC Package 6-Lead Plastic DFN (2mm × 2mm) (Reference LTC DWG # 05-08-1703) R = 0.115 TYP 0.56 ± 0.05 (2 SIDES) 2.00 ± 0.10 (4 SIDES) PIN 1 CHAMFER OF EXPOSED PAD 3 0.25 ± 0.05 0.50 BSC 1.42 ± 0.05 (2 SIDES) RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS NOTE: 1. DRAWING TO BE MADE A JEDEC PACKAGE OUTLINE M0-229 VARIATION OF (WCCD-2) 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 0.200 REF 0.75 ± 0.05 1 (DC6) DFN 1103 0.38 ± 0.05 4 6 0.675 ± 0.05 2.50 ± 0.05 1.15 ± 0.05 0.61 ± 0.05 (2 SIDES) PACKAGE OUTLINE PIN 1 BAR TOP MARK (SEE NOTE 6) 0.25 ± 0.05 0.50 BSC 1.37 ± 0.05 (2 SIDES) 0.00 – 0.05 BOTTOM VIEW—EXPOSED PAD 3590f 14 LT3590 PACKAGE DESCRIPTION SC8 Package 8-Lead Plastic SC70 (Reference LTC DWG # 05-08-1639 Rev Ø) 0.30 MAX 0.50 REF PIN 8 1.80 – 2.20 (NOTE 4) 1.00 REF 2.8 BSC 1.8 REF 1.80 – 2.40 1.15 – 1.35 (NOTE 4) INDEX AREA (NOTE 6) PIN 1 RECOMMENDED SOLDER PAD LAYOUT PER IPC CALCULATOR 0.10 – 0.40 0.50 BSC 0.15 – 0.27 8 PLCS (NOTE 3) 0.80 – 1.00 0.00 – 0.10 REF 1.00 MAX GAUGE PLANE 0.15 BSC 0.26 – 0.46 0.10 – 0.18 (NOTE 3) NOTE: 1. DIMENSIONS ARE IN MILLIMETERS 2. DRAWING NOT TO SCALE 3. DIMENSIONS ARE INCLUSIVE OF PLATING 4. DIMENSIONS ARE EXCLUSIVE OF MOLD FLASH AND METAL BURR SC8 SC70 0905 REV Ø 5. MOLD FLASH SHALL NOT EXCEED 0.254mm 6. DETAILS OF THE PIN 1 IDENTIFIER ARE OPTIONAL, BUT MUST BE LOCATED WITHIN THE INDEX AREA 7. EIAJ PACKAGE REFERENCE IS EIAJ SC-70 AND JEDEC MO-203 VARIATION BA 3590f 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 representation that the interconnection of its circuits as described herein will not infringe on existing patent rights. 15 LT3590 TYPICAL APPLICATION 24V Supply for 6 LED String, 50mA Current C2 1μF R1 4Ω VIN 24V 50mA EFFICIENCY (%) 100 95 90 85 80 75 70 65 3590 TA08a Conversion Efficiency C1 1μF VIN CTRL LT3590 VREG LED L1 220μH SW GND CONTROL >1.5V C3 0.1μF 60 0 10 20 30 LED CURRENT (mA) 40 50 3590 TA08b L1: MURATA LQH32CN-221 RELATED PARTS PART NUMBER DESCRIPTION LT1932 LT3003 LT3465/A LT3466/-1 LT3474 LT3475 LT3476 LT3478/-1 LT3486 LT3491 LT3496 LT3497 LT3498 LT3517 LT3518 LT3591 Constant Current, 1.2MHz, High Efficiency White LED Boost Regulator Three Channel LED Ballaster with PWM Dimming Constant Current, 1.2/2.7MHz, High Efficiency White LED Boost Regulator with Integrated Schottky Diode Dual Constant Current, 2MHz, High Efficiency White LED Boost Regulator with Integrated Schottky Diode 36V, 1A (ILED), 2MHz,Step-Down LED Driver Dual 1.5A(ILED), 36V, 2MHz, Step-Down LED Driver Quad Output 1.5A, 2MHz High Current LED Driver with 1,000:1 Dimming 4.5A, 2MHz High Current LED Driver with 3,000:1 Dimming Dual 1.3A, 2MHz High Current LED Driver Constant Current, 2.3MHz, High Efficiency White LED Boost Regulator with Integrated Schottky Diode Triple Output 750mA, 2.1 MHz High Current LED Driver with 3,000:1 Dimming COMMENTS VIN: 1.0V to 10.0V, VOUT(MAX) = 34V, Dimming Analog/PWM, ISD < 1μA, ThinSOT™ Package VIN: 3.0V to 48.0V, Dimming 3,000:1 True Color PWM™, ISD