LT3492

FEATURES n n n n n n n n n n n n n n n Three 100mA Buck Regulators, Each Drives Up to 10 LEDs with Fast NPN Current Sources Fast Current Sources for 3 1-3 >3 1-3 >3 COUT (µF) 3.3 2.2 4.7 3.3 15 6.8 Sumida www.sumida.com Diode Selection Schottky diodes, with their low forward voltage drop and fast switching speed, must be used for all LT3597 applications. Do not use P-N junction diodes. The diode’s average current rating must exceed the application’s average current. The diode’s maximum reverse voltage must exceed the application’s input voltage. Table 4 lists some recommended Schottky diodes. Table 4. Recommended Diodes PART DFLS160 B160 CMMSH1-60 ESIPB MAX CURRENT MAX REVERSE (A) VOLTAGE (V) 1 1 1 1 60 60 60 100 MANUFACTURER Diodes, Inc. www.diodes.com Central www.centralsemi.com Vishay www.vishay.com Toko www.toko.com TDK www.tdk.com Coiltronics www.cooperet.com Capacitor Selection Low ESR (equivalent series resistance) capacitors should be used at the outputs to minimize output ripple voltage. Use only X5R or X7R dielectrics, as these materials retain their capacitance over wider voltage and temperature ranges than other dielectrics. Table 2 lists some suggested manufacturers. Consult the manufacturers for detailed information on their entire selection of ceramic surface mount parts. Table 2. Recommended Ceramic Capacitor Manufacturers Taiyo Yuden AVX Murata Kemet TDK www.t-yuden.com www.avxcorp.com www.murata.com www.kemet.com www.tdk.com 3597f 11 LT3597 APPLICATIONS INFORMATION Undervoltage Lockout (UVLO) The EN/UVLO can be used to program the input UVLO threshold by connecting it to a resistor divider from the VIN pin as shown in Figure 2. LT3597 VIN R2 R1 EN/UVLO Programming Maximum LED Current Maximum LED current can be programmed by placing a resistor (RISET1-3) between the ISET1-3 pin and ground. RISET1-3 values between 20k and 100k can be chosen to set the maximum LED current between 100mA and 20mA respectively. The LED current is programmed according to the following equation: + – 1.51V ILED1-3 = 2 • 1V RISET1-3 (mA) 3597 F02 Figure 2. EN/UVLO Control See Table 5 and Figure 3 for resistor values and corresponding programmed LED current. Table 5. LED Current Programming RISET1-3 VALUE (kΩ) 20 25 33.3 50 100 LED CURRENT (mA) 100 80 60 40 20 Select R1 and R2 according to the following equation:  R2  VIN(UVLO) = 1.51V •  1+   R1 In UVLO an internal 5.1µA pull-down current source is connected to the pin for programmable UVLO hysteresis. The hysteresis can be set according to the following equation: VUVLO(HYST) = 5.1µA • R2 100 LED CURRENT (mA) Care must be taken if too much hysteresis is programmed, the pin voltage might drop too far and cause the current source to saturate. Once the EN/UVLO pin falls below 0.4V, the part enters into shutdown. 80 60 40 20 0 0 25 50 RSET1-3 (k ) 75 100 3597 F03 Figure 3. RISET1-3 Value for LED Current 3597f 12 LT3597 APPLICATIONS INFORMATION LED Current Dimming Two different types of dimming control are available with the LT3597. The LED current can be dimmed using the CTRL1-3 pin or the PWM1-3 pin. For some applications, a variable DC voltage that adjusts the LED current is the preferred method for brightness control. In that case, the CTRL1-3 pin can be modulated to set the LED dimming (see Figure 4). As the CTRL1-3 pin voltage rises from 0V to 1.0V, the LED current increases from 0mA to the maximum programmed LED current in a linear fashion. As the CTRL1-3 pin continues to increase past 1.0V, the maximum programmed LED current is maintained. If this type of dimming control is not desired, the CTRL1-3 pin can be tied to VREF . 120 100 LED CURRENT (mA) 80 60 40 20 0 For True Color PWM dimming, the LT3597 provides up to 10,000:1 PWM dimming range at 100Hz. This is achieved by allowing the duty cycle of the PWM1-3 pin to be reduced from 100% to 0.01% for a PWM frequency of 100Hz (see Figure 5), hence a minimum on-time of 1µs and a maximum period of 100ms. PWM duty cycle dimming allows for constant LED color to be maintained over the entire dimming range. Using the TSET Pin for Thermal Protection The LT3597 contains a special programmable thermal regulation loop that limits the internal junction temperature. This thermal regulation feature provides important protection at high ambient temperatures, and allows a given application to be optimized for typical, not worstcase, ambient temperatures with the assurance that the LT3597 will automatically protect itself and the LED strings under worst-case conditions. As the ambient temperature increases, so does the internal junction temperature of the part. Once the programmed maximum junction temperature is reached, the LT3597 linearly reduces the LED current, as needed, to maintain this junction temperature. This can only be achieved when the ambient temperature stays below the maximum programmed junction temperature. If the ambient temperature continues to rise above the programmed maximum junction temperature, the LED current will reduce to less than 20% of the full current. A resistor divider from the VREF pin programs the maximum part junction temperature as shown in Figure 6. LT3597 0 0.25 0.5 0.75 1 CTRL1-3 (V) 1.25 1.5 3597 F04 Figure 4. LED Current vs CTRL1-3 Voltage tPWM tON(PWM) PWM1-3 LED1-3 CURRENT MAX ILED 3597 F06 VREF R2 TSET R1 3597 F07 Figure 5. LED Current Using PWM Dimming Figure 6. Programming the TSET Pin 3597f 13 LT3597 APPLICATIONS INFORMATION Table 6 shows commonly used values for R1 and R2. Choose the ratio of R1 and R2 for the desired junction temperature limit as described in Figure 7. Table 6. TSET Programmed Junction Temperature TJ (°C) 85 100 115 R1 (kΩ) 49.9 49.9 49.9 R2 (kΩ) 97.6 90.9 84.5 LED Current Derating Using the CTRLM Pin Another feature of the LT3597 is its ability to program a derating curve for maximum LED current versus temperature. LED data sheets provide curves of maximum allowable LED current versus temperature to warn against exceeding this current limit and damaging the LED. The LT3597 allows the output LEDs to be programmed for maximum allowable current while still protecting the LEDs from excessive currents at high temperature. This is achieved by programming a voltage at the CTRLM pin with a negative temperature coefficient using a resistor divider with temperature dependent resistance (Figure 8). As ambient temperature increases, the CTRLM voltage will fall below the internal 1V voltage reference, causing LED currents to be controlled by the CTRLM pin voltage. The LED current curve breakpoint and slope versus temperature are defined by the choice of resistor ratios and use of temperature-dependent resistance in the divider for the CTRLM pin. LT3597 VREF R2 R1 (OPTION A TO D) CTRLM RNTC A B RNTC RX RY RY RNTC C D 3597 F08 The TSET pin must be tied to VREF if the temperature protection feature is not desired. 0.8 0.7 TSET VOLTAGE (V) 0.6 0.5 0.4 0.3 –50 –25 75 0 25 50 TEMPERATURE (°C) 100 125 RNTC RX 3597 F07 Figure 7. TSET Voltage for Temperature Derating Figure 8. Programming the CTRLM Pin 3597f 14 LT3597 APPLICATIONS INFORMATION Table 7 shows a list of manufacturers/distributors of NTC resistors. There are several other manufacturers available and the chosen supplier should be contacted for more detailed information. If an NTC resistor is used to indicate LED temperature, it is effective only if the resistor is placed as closely as possible to the LED strings. LED derating curves shown by manufacturers are listed for ambient temperature. The NTC resistor should have the same ambient temperature as the LEDs. Since the temperature dependency of an NTC resistor can be nonlinear over a wide range of temperatures, it is important to obtain a resistor’s exact value over temperature from the manufacturer. Hand calculations of the CTRLM voltage can then be performed at each given temperature, resulting in the CTRLM versus temperature plotted curve. Iterations of resistor value calculations may be necessary to achieve the desired break point and slope of the LED current derating curve. From the CTRLM voltage, the LED current can be found using the curve shown in Figure 9. Table 7. NTC Resistor Manufacturers/Distributors Murata TDK Corporation Digi-Key www.murata.com www.tdk.com www.digikey.com Murata Electronics provides a selection of NTC resistors with complete data over a wide range of temperatures. In addition, a software tool is available which allows the user to select from different resistor networks and NTC resistor values, and then simulate the exact output voltage curve (CTRLM behavior) over temperature. Referred to as the “Murata Chip NTC Thermistor Output Voltage Simulator,” users can log onto www.murata.com and download the software followed by instructions for creating an output voltage VOUT (CTRLM) from a specified VCC supply (VREF). The CTRLM pin must be tied to VREF if the temperature derating function is not desired. Programming Switching Frequency The switching frequency of the LT3597 can be programmed between 200kHz and 1MHz by an external resistor connected between the RT pin and ground. Do not leave this pin open. See Table 8 and Figure 10 for resistor values and corresponding frequencies. Table 8. RT Resistor Selection SWITCHING FREQUENCY (MHz) 1.0 0.5 0.2 RT VALUE (kΩ) 33.2 80 220 If calculating the CTRLM voltage at various temperatures gives a downward slope that is too strong, use alternative resistor networks (B, C, D in Figure 8). They use temperature independent resistance to reduce the effects off the NTC resistor over temperature. 120 1.2 SWITCHING FREQUENCY (MHz) 0 0.25 0.5 0.75 1 CTRLM (V) 1.25 1.5 3597 F09 100 LED CURRENT (mA) 80 60 40 20 0 1.0 0.8 0.6 0.4 0.2 0 25 50 75 100 125 150 175 200 225 RT (k ) 3597 F10 Figure 9. LED Current vs CTRLM Voltage Figure 10. Programming Switching Frequency 3597f 15 LT3597 APPLICATIONS INFORMATION Selecting the optimum switching frequency depends on several factors. Inductor size is reduced with higher frequency, but efficiency drops slightly due to higher switching losses. Some applications require very low duty cycles to drive a small number of LEDs from a high supply. Low switching frequency allows a greater range of operational duty cycle and hence a lower number of LEDs can be driven. In each case, the switching frequency can be tailored to provide the optimum solution. When programming the switching frequency, the total power losses within the IC should be considered. Switching Frequency Synchronization The nominal operating frequency of the LT3597 is programmed using a resistor from the RT pin to ground over a 200kHz to 1MHz range. In addition, the internal oscillator can be synchronized to an external clock applied to the SYNC pin. The synchronizing clock signal input to the LT3597 must have a frequency between 240kHz and 1MHz, a duty cycle between 20% and 80%, a low state below 0.4V and a high state above 1.6V. Synchronization signals outside of these parameters will cause erratic switching behavior. For proper operation, an RT resistor is chosen to program a switching frequency 20% slower than the SYNC pulse frequency. Synchronization occurs at a fixed delay after the rising edge of SYNC. The SYNC pin must be grounded if the clock synchronization feature is not used. When the SYNC pin is grounded, the internal oscillator controls the switching frequency of the converter. Operating Frequency Trade-offs Selection of the operating frequency is a trade-off between efficiency, component size, output voltage and maximum input voltage. The advantage of high frequency operation is smaller component sizes and values. The disadvantages are lower efficiency and lower input voltage range for a desired output voltage. The highest acceptable switching frequency (fSW(MAX)) for a given application can be calculated as follows: fSW(MAX) = VD + VOUT tON(MIN) ( VD + VIN − VSW ) where VIN is the typical input voltage, VOUT is the output voltage, VD is the catch diode drop (0.5V) and VSW is the internal switch drop (0.5V at max load). This equation shows that slower switching is necessary to accommodate high VIN /VOUT ratios. The reason the input voltage range depends on the switching frequency is due to the finite minimum switch on and off times. The switch minimum on and off times are 200ns. Adaptive Loop Control The LT3597 uses an adaptive control mechanism to set the buck output voltage. This control scheme ensures maximum efficiency while not compromising minimum PWM pulse widths. When PWM1-3 is low, the output of the respective buck rises to a maximum value set by an external resistor divider to the respective FB pin. Once PWM1-3 goes high, the output voltage is adaptively reduced until the voltage across the LED current sink is 1V. Figure 11 shows how the maximum output voltage can be set by an external resistor divider. LT3597 VOUT1-3 R2 FB1-3 R1 3597 F11 VOUT1-3 Figure 11. Programming Maximum VOUT1-3 3597f 16 LT3597 APPLICATIONS INFORMATION The maximum output voltage must be set to exceed the maximum LED drop plus 1V by a margin greater than 10%. However, this margin must not exceed a voltage of 10V. This ensures proper adaptive loop control. The equations below are used to estimate the resistor divider ratio. The sum of the resistors should be less than 100k to avoid noise coupling to the FB pin.  R2  VOUT(MAX) = 1.1 VLED(MAX) + 1.1V = 1.2V •  1+   R1 Fault Flag The FAULT pin is an open-collector output and needs an external resistor tied to a supply. If the LED1-3 pin voltage exceeds 12V or if the LED1-3 pin voltage is within 1.25V of VOUT1-3 pins while PWM1-3 is high, the FAULT pin will be pulled low. The FAULT pin will also be pulled low if the internal junction temperature exceeds the TSET programmed temperature limit. There is a 3µs delay for FAULT flag generation when the PWM1-3 signal is enabled to avoid generating a spurious flag signal. The maximum current the FAULT can sink is typically 1mA. Thermal Considerations The LT3597 provides three channels for LED strings with internal NPN devices serving as constant current sources. When LED strings are regulated, the lowest LED pin voltage is typically 1V. More power dissipation occurs in the LT3597 at higher programmed LED currents. For 100mA of LED current with a 100% PWM dimming ratio, at least 300mW is dissipated within the IC due to current sources. Thermal calculations must include the power dissipation in the current sources in addition to conventional switch DC loss, switch transient loss and input quiescent loss. In addition, the die temperature of the LT3597 must be lower than the maximum rating of 125°C. This is generally not a concern unless the ambient temperature is above 100°C. Care should be taken in the board layout to ensure good heat sinking of the LT3597. The maximum load current should be derated as the ambient temperature approaches 125°C. The die temperature rise above ambient is calculated by multiplying the LT3597 power dissipation by the thermal resistance from junction to ambient. Power dissipation within the LT3597 is estimated by calculating the total power loss from an efficiency measurement and subtracting the losses of the catch diode and the inductor. Thermal resistance depends on the layout of the circuit board, but 32°C/W is typical for the 5mm × 8mm QFN package. ( ) VOUT(MAX) = VLED(MAX) +1.1V +VMARGIN VMARGIN ≤ 10V Minimum Input Voltage The minimum input voltage required to generate an output voltage is limited by the maximum duty cycle and the output voltage (VOUT) set by the FB resistor divider. The duty cycle is: VD + VOUT DC = VIN − VCESAT + VD where VD is the Schottky forward drop and VCESAT is the saturation voltage of the internal switch. The minimum input voltage is:  VD + VOUT(MAX)  VIN(MIN) =   + VCESAT − VD DCMAX   where VOUT(MAX) is calculated from the equation in the Adaptive Loop Control section, and DCMAX is the minimum rating of the maximum duty cycle. 3597f 17 LT3597 APPLICATIONS INFORMATION Board Layout 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). Always use a ground plane under the switching regulator to minimize interplane coupling. Good grounding is essential in LED fault detection. Proper grounding is also essential for the external resistors and resistor dividers that set critical operation parameters. Both the LT3597 exposed pad and pin 18 are ground. Resistors connected between ground and the CTRL1-3, CTRLM, FB1-3, TSET, ISET1-3, RT and EN/UVLO pins are best tied to pin 18 and not the ground plane. 3597f 18 LT3597 TYPICAL APPLICATIONS 48V 1MHz Triple Step-Down 100mA RGB LED Driver VIN 48V VIN EN/UVLO 91k BOOST1 VOUT1 97k R 9.1k 100µH 3.3µF DA1 FB1 VOUT1 LED1 BIAS 10µF 3 3 100k FAULT PWM1-3 CTRL1-3 SYNC RT 33.2k (1MHz) ISET1 20k ISET2 20k ISET3 20k GND LT3597 VOUT2 LED2 BOOST3 0.1µF 100µH SW3 2.2µF DA3 FB3 VOUT3 LED3 VREF TSET CTRLM 3597 TA02 10µF 270k BOOST2 0.1µF 100µH SW2 2.2µF DA2 FB2 4.7k B 97k VOUT2 0.1µF SW1 VOUT3 97k 3.83k G VCC 5V 10k 82.5k 49.9k VREF 100k Efficiency 90 80 70 EFFICIENCY (%) 60 50 40 30 20 10 0 0 10 20 30 40 50 60 70 80 90 100 LED CURRENT PER CHANNEL (mA) 3597 TA02b 3597f 19 LT3597 TYPICAL APPLICATIONS 48V 1MHz Triple Step-Down 10W 100mA White LED Driver (3.6V LEDs) VIN 48V 10µF 270k 91k VIN EN/UVLO BOOST1 BOOST2 0.1µF 100µH SW2 2.2µF DA2 FB2 VOUT2 LED2 BOOST3 0.1µF 100µH SW3 2.2µF DA3 FB3 3.24k VOUT3 97k 3.24k VOUT2 97k VOUT1 97k 3.24k 100µH 2.2µF 0.1µF SW1 DA1 FB1 VOUT1 LED1 BIAS LT3597 VCC 5V 10µF 3 3 100k FAULT PWM1-3 CTRL1-3 SYNC RT 33.2k ISET1 20k ISET2 20k ISET3 20k VOUT3 LED3 VREF TSET GND CTRLM 3597 TA03 10k 82.5k 49.9k VREF 100k Efficiency 90 80 70 EFFICIENCY (%) 60 50 40 30 20 10 0 0 10 20 30 40 50 60 70 80 90 100 LED CURRENT PER CHANNEL (mA) 3597 TA03b 3597f 20 LT3597 TYPICAL APPLICATIONS 24V 200kHz Triple Step-Down 100mA RGB LED Driver VIN 24V VIN EN/UVLO BOOST1 VOUT1 97k R 9.1k 470µH 15µF DA1 FB1 VOUT1 LED1 BIAS 10µF 3 3 100k FAULT PWM1-3 CTRL1-3 SYNC RT 220k ISET1 20k ISET2 20k ISET3 20k GND LT3597 VOUT2 LED2 BOOST3 SW3 15µF DA3 FB3 VOUT3 LED3 VREF TSET CTRLM 3597 TA04 10µF BOOST2 SW2 0.22µF 470µH 15µF 97k VOUT2 DA2 FB2 9.1k G 0.22µF SW1 0.22µF 470µH 97k VOUT3 9.1k B VREF Efficiency 90 80 70 EFFICIENCY (%) 60 50 40 30 20 10 0 0 10 20 30 40 50 60 70 80 90 100 LED CURRENT PER CHANNEL (mA) 3597 TA04b 3597f 21 LT3597 TYPICAL APPLICATIONS 48V 1MHz Triple Step-Down 20mA RGB LED Driver VIN 48V VIN EN/UVLO 91k BOOST1 VOUT1 97k R 9.1k 100µH 3.3µF DA1 FB1 VOUT1 LED1 BIAS 10µF 3 3 100k FAULT PWM1-3 CTRL1-3 SYNC RT 33.2k ISET1 100k ISET2 100k ISET3 100k GND LT3597 VOUT2 LED2 BOOST3 0.1µF 100µH SW3 2.2µF DA3 FB3 VOUT3 LED3 VREF TSET CTRLM 3597 TA05 10µF 270k BOOST2 0.1µF 100µH SW2 2.2µF DA2 FB2 4.7k B 97k VOUT2 0.1µF SW1 VOUT3 97k 3.83k G VCC 5V 10k 82.5k 49.9k VREF 100k 3597f 22 LT3597 PACKAGE DESCRIPTION (Reference LTC DWG # 05-08-1846 Rev B) 43 41 39 37 6.40 REF 35 34 33 32 31 30 29 28 27 0.70 ± 0.05 44 46 48 2.90 ±0.05 5.90 ±0.05 26 25 24 23 22 3.20 REF 21 20 19 18 PACKAGE OUTLINE 2 4 6 0.80 BSC 7 9 11 12 13 14 15 16 0.40 BSC 17 0.20 ± 0.05 UHG Package Variation: UHG52 (39) 52-Lead Plastic QFN (5mm × 8mm) 5.50 ± 0.05 4.10 ± 0.05 50 51 7.10 ± 0.05 8.50 ± 0.05 RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS APPLY SOLDER MASK TO AREAS THAT ARE NOT SOLDERED 51 50 48 46 44 PIN 1 NOTCH R = 0.30 TYP OR 0.35 × 45° CHAMFER 50 51 0.40 ±0.10 43 43 2 41 4 39 6 7 9 8.00 ± 0.10 11 12 13 14 15 16 17 37 35 34 33 32 31 30 29 28 27 37 35 6.40 REF 34 33 32 31 30 29 28 27 5.90 ±0.10 2.90 ±0.10 39 6 7 9 11 12 13 14 15 16 17 0.70 TYP 0.200 REF 0.75 ± 0.05 18 19 20 21 22 23 24 25 26 0.00 – 0.05 NOTE: 1. DRAWING IS NOT A JEDEC PACKAGE OUTLINE 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 0.20mm 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 26 25 24 23 22 21 20 19 3.20 REF BOTTOM VIEW—EXPOSED PAD 18 (UHG39) QFN 0410 REV B 5.00 ± 0.10 PIN 1 TOP MARK (SEE NOTE 6) 0.75 ± 0.05 0.00 – 0.05 R = 0.10 TYP 44 R = 0.10 TYP 46 48 2 41 4 0.20 ± 0.05 0.80 BSC 0.60 TYP 0.40 BSC 3597f 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. 23 LT3597 TYPICAL APPLICATION Triple Step-Down RGB Single Pixel LED Driver, 100mA Current VIN 48V 10µF 270k 91k BOOST1 VOUT1 97k R 9.1k 100µH 3.3µF DA1 FB1 VOUT1 LED1 BIAS 10µF 100k FAULT PWM1:3 CTRL1:3 SYNC RT 33.2k ISET1 20k ISET2 20k ISET3 20k GND LT3597 VOUT2 LED2 BOOST3 0.1µF 100µH SW3 3.3µF DA3 FB3 VOUT3 LED3 VREF TSET CTRLM 3597 TA06 10,000:1 Dimming at 100Hz VOUT2 3.3µF 97k 9.1k G PWM 2V/DIV VIN EN/UVLO BOOST2 0.1µF 100µH SW2 DA2 FB2 0.1µF SW1 ILED 50mA/DIV VOUT3 97k 9.1k B 200ns/DIV 3597 TA06b VCC 5V 10µF 10k 82.5k 49.9k VREF 100k RELATED PARTS PART NUMBER DESCRIPTION LT3476 LT3492 LT3496 LT3590 LT3595 LT3596 LT3598 LT3599 LT3754 LT3760 Quad Output 1.5A, 2MHz High Current LED Driver with 1000:1 Dimming 60V, 2.1MHz 3-Channel (ILED = 1A) Full Featured LED Driver 45V, 2.1MHz 3-Channel (ILED = 1A) Full Featured LED Driver 48V, 850kHz 50mA Buck Mode LED Driver 45V, 2.5MHz 16-Channel Full Featured LED Driver 60V, 1MHz 3-Channel Full Featured LED Driver 44V, 1.5A, 2.5MHz Boost 6-Channel LED Driver COMMENTS VIN: 2.8V to 16V, VOUT(MAX) = 36V, True Color PWM Dimming = 1000:1, ISD < 10µA, 5mm × 7mm QFN-10 Package VIN: 3V to 30V (40VMAX), VOUT(MAX) = 60V, True Color PWM Dimming = 3000:1, ISD < 1µA, 4mm × 5mm QFN-28 Package VIN: 3V to 30V (40VMAX), VOUT(MAX) = 45V, True Color PWM Dimming = 3000:1, ISD < 1µA, 4mm × 3mm QFN-28 Package VIN: 4.5V to 55V, True Color PWM Dimming = 200:1, ISD < 15µA, 2mm × 2mm DFN-6 and SC70 Packages VIN: 4.5V to 55V, VOUT(MAX) = 45V True Color PWM Dimming = 5000:1, ISD < 1µA, 5mm × 9mm QFN-56 Package VIN: 6V to 60V, VOUT(MAX) = 40V, True Color PWM Dimming = 10,000:1, ISD ≤ 2µA, 5mm × 8mm QFN-52 Package VIN: 3V to 30V (40VMAX), VOUT(MAX) = 44V, True Color PWM Dimming = 1000:1, ISD < 1µA, 4mm × 4mm QFN-24 Package 2A Boost Converter with Internal 4-String 150mA LED VIN: 3V to 30V, VOUT(MAX) = 44V, True Color PWM Dimming = 1000:1, ISD < 1µA, 5mm × 5mm QFN-32 and TSSOP-28 Packages Ballaster 16-Channel x 50mA LED Driver with 60V Boost Controller and PWM Dimming 8-Channel x 100mA LED Driver with 60V Boost Controller and PWM Dimming VIN: 6V to 40V, VOUT(MAX) = 60V, True Color PWM Dimming = 3000:1, ISD < 2µA, 5mm × 5mm QFN-52 Package VIN: 6V to 40V, VOUT(MAX) = 60V, True Color PWM Dimming = 3000:1, ISD < 2µA, TSSOP-28 Package 3597f 24 Linear Technology Corporation 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 ● FAX: (408) 434-0507 ● LT 0311 • PRINTED IN USA www.linear.com  LINEAR TECHNOLOGY CORPORATION 2011