LT3591 White LED Driver with Integrated Schottky in 3mm 2mm DFN DESCRIPTION FEATURES APPLICATIONS TYPICAL APPLICATION

Transcription

1 FEATURES Drives Up to Ten White s from a 3V Supply High Side Sense Allows One Wire Current Source Internal Schottky Diode One Pin Dimming and Shutdown 8: True Color PWM TM Dimming Range V Open Protection MHz Switching Frequency ±% Reference Accuracy Range:.V to V Requires Only.µF Output Capacitor Low Profile 8-Lead DFN Package (3mm mm.7mm) APPLICATIONS Cellular Phones PDAs, Handheld Computers Digital Cameras MP3 Players GPS Receivers White Driver with Integrated Schottky in 3mm mm DFN DESCRIPTION The LT 39 is a fixed frequency step-up DC/DC converter specifi cally designed to drive up to ten white s in series from a Li-Ion cell. Series connection of the s provides identical currents resulting in uniform brightness and eliminating the need for ballast resistors. The device features a unique high side current sense that enables the part to function as a one wire current source; one side of the string can be returned to ground anywhere, allowing a simpler one wire connection. Traditional drivers use a grounded resistor to sense current, requiring a -wire connection to the string. The high switching frequency allows the use of tiny inductors and capacitors. A single pin performs both shutdown and accurate dimming control. Few external components are needed: open- protection and the Schottky diode are all contained inside a low profi le 3mm mm DFN package., LT, LTC and LTM 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. TYPICAL APPLICATION Li-Ion Driver for Ten White s Conversion Effi ciency SHUTDOWN AND DIMMING CONTROL 8 = 3.6V s 3V TO V µh Ω.µF CURRENT (ma) 39 TAb 39 TAa

2 ABSOLUTE MAXIMUM RATINGS (Note ) Input Voltage ( )... V Voltage... V Voltage... V Voltage... V Voltage... V Operating Junction Temperature Range (Note )... C to 8 C Maximum Junction Temperature... C Storage Temperature Range... 6 C to C PACKAGE/ORDER INFORMATION NC 3 TOP VIEW 9 DDB PACKAGE 8-LEAD (3mm mm) PLASTIC DFN T JMAX = C, θ JA = 76 C/W EXPOSED PAD (PIN 9) SHOULD BE CONNECTED TO PCB GROUND ORDER PART NUMBER EDDB NC DDB PART MARKING LCPG Order Options Tape and Reel: Add #TR Lead Free: Add #PBF Lead Free Tape and Reel: Add #TRPBF Lead Free Part Marking: Consult LTC Marketing for parts specified with wider operating temperature ranges. ELECTRICAL CHARACTERISTICS The denotes the specifi cations which apply over the full operating temperature range, otherwise specifications are at T A = C. = 3V, V = 3V, unless otherwise specified. PARAMETER CONDITIONS MIN TYP MAX UNITS Minimum Operating Voltage. V Current Sense Voltage (V V ) V = V, I = 3mA 9 mv Pin Bias Current V = 36V, V = 3.8V 8 µa Pin Bias Current V = 36V, V = 3.8V µa Supply Current V = V, V = 3V = V 9 ma µa Switching Frequency.7. MHz Maximum Duty Cycle 9 9 % Switch Current Limit 8 ma Switch V CESAT I = 3mA mv Switch Leakage Current V = V. µa V for Full Current V = V. V V to Shut Down IC mv V to Turn On IC mv Pin Bias Current na Pin Overvoltage Protection V Schottky Forward Drop I SCHOTTKY = ma.8 V Schottky Leakage Current V R = 3V µa Note : 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 : The E is guaranteed to meet performance specifications from C to 8 C operating junction temperature range. Specifications over the C to 8 C operating junction temperature range are assured by design, characterization and correlation with statistical process controls.

3 TYPICAL PERFORMANCE CHARACTERISTICS T A = C, unless otherwise specifi ed. Switch Saturation Voltage (V CESAT ) Schottky Forward Voltage Drop Shutdown Current (V = V) 6 ITCH SATURATION VOLTAGE (mv) 3 C C C SCHOTTKY FORWARD CURRENT (ma) 3 C C C SHUTDOWN CURRENT (µa) C C C ITCH CURRENT (ma) 6 8 SCHOTTKY FORWARD DROP (mv) (V) 39 G 39 G 39 G3 SENSE VOLTAGE (mv) 6 8 Sense Voltage (V V ) vs V C C C OUTPUT CLAMP VOLTAGE (V) 3 Open-Circuit Output Clamp Voltage C C C INPUT CURRENT (ma) Input Current in Output Open Circuit C C C 3 V (mv) (V) (V) 39 G 39 G 39 G6 Switching Waveform Transient Response V V/DIV V V/DIV V mv/div V V/DIV I L ma/div I L ma/div = 3.6V ms/div FRONT PAGE APPLICATION CIRCUIT 39 G7 = 3.6V ms/div FRONT PAGE APPLICATION CIRCUIT 39 G8 3

4 TYPICAL PERFORMANCE CHARACTERISTICS T A = C, unless otherwise specified. QUIESCENT CURRENT (ma) 6 3 Quiescent Current (V = 3V) Current Limit vs Temperature C C C CURRENT LIMIT (ma) 8 6 SCHOTTKY LEAKAGE CURRENT (µa) Schottky Leakage Current vs Temperature V R = V V R = 6V V R = V (V) 7 7 TEMPERATURE ( C) TEMPERATURE ( C) 39 G9 39 G 39 G OUTPUT CLAMP VOLTAGE (V) 3 Open-Circuit Output Clamp Voltage vs Temperature INPUT CURRENT (ma) Input Current in Output Open Circuit vs Temperature = 3V ITCHING FREQUENCY (khz) Switching Frequency vs Temperature 7 TEMPERATURE ( C) 7 TEMPERATURE ( C) 7 7 TEMPERATURE ( C) 39 G 39 G3 39 G Maximum Duty Cycle vs Temperature 8 Sense Voltage (V V ) Sense Voltage (V V ) vs V vs Temperature 8 MAXIMUM DUTY CYCLE (%) SENSE VOLTAGE (mv) 96 9 C C C SENSE VOLTAGE (mv) TEMPERATURE ( C) V (V) 88 7 TEMPERATURE ( C) 39 G 39 G6 39 G7

5 PIN FUNCTIONS (Pin ): Input Supply Pin. Must be locally bypassed. (Pin ): Ground Pin. Should be tied directly to local ground plane. (Pin ): Switch Pin. Minimize trace area at this pin to minimize EMI. Connect the inductor at this pin. (Pin ): Output of the Driver. This pin is connected to the cathode of internal Schottky. Connect the output capacitor to this pin and the sense resistor from this pin to the pin. (Pin 7): Connection Point for the Anode of the First and the Sense Resistor. The current can be programmed by : mv I = R SENSE (Pin 8): Dimming and Shutdown Pin. Connect this pin below mv to disable the driver. As the pin voltage is ramped from V to.v, the current ramps from to I ( = mv/ ). The pin must not be left fl oating. Exposed Pad (Pin 9): Ground. The Exposed Pad must be soldered to PCB ground to achieve the rated thermal performance. BLOCK DIAGRAM + A PWM COMP R Q S DRIVER + Q OVERVOLTAGE PROTECTION Σ A3 R RAMP GENERATOR SHDN V REF.V OSCILLATOR A + A = R C + START-UP CONTROL C C 8 39 F Figure. Block Diagram

6 OPERATION The 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 in Figure. At power-up, the capacitor at the pin is charged up to (input supply voltage) through the inductor and the internal Schottky diode. If is pulled higher than mv, the bandgap reference, the start-up bias and the oscillator are turned on. At the start of each oscillator cycle, the power switch Q is turned 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, A. When this voltage exceeds the level at the negative input of A, the PWM logic turns off the power switch. The level at the negative input of A is set by the error amplifier A, and is simply an amplified version of the difference between the V and V voltage and the bandgap reference. In this manner the error amplifier, A, sets the correct peak current level in inductor to keep the output in regulation. The pin is used to adjust the current. The enters into shutdown when is pulled lower than mv. Minimum Output Current The can drive a - string at ma current without pulse skipping using the same external components shown in the application circuit on the front page of this data sheet. As current is further reduced, the device will begin skipping pulses. This will result in some low frequency ripple, although the average current remains regulated down to zero. The photo in Figure details circuit operation driving two white s at ma load. Peak inductor current is less than ma and the regulator operates in discontinuous mode, meaning the inductor current reaches zero during the discharge phase. After the inductor current reaches zero, the 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. I L ma/div V V/DIV =.V I = ma s ns/div 39 F Figure. Switching Waveforms 6

7 APPLICATIONS INFORMATION INDUCTOR SELECTION A µh inductor is recommended for most applications. Although small size and high efficiency are major concerns, the inductor should have low core losses at MHz and low DCR (copper wire resistance). Some small inductors in this category are listed in Table. The efficiency comparison of different inductors is shown in Figure 3. Table. Recommended Inductors PART VLFAT- MR VLCF8T- MR9- VLCFT- MR6 L (µh) CURRENT RATING (ma) MAX DIMENSION L W H (mm) VENDOR 3.8. TDK LQH3CNK Murata NR8TM Taiyo Yuden NRTM... CDRH3D8- NC 6 Sumida B87-A3-M Epcos ACITOR SELECTION The small size of ceramic capacitors make them ideal for applications. Use only XR and X7R types because they retain their capacitance over wider temperature ranges than other types such as YV or ZU. A input capacitor and a V,.µF output capacitor are suffi cient for most applications. A limited number of manufacturers produce small V capacitors. Table shows a list of several recommended V capacitors. Consult the manufacturer for detailed information on their entire selection of ceramic parts. Table. Recommended Output Capacitors PART VOLTAGE C (µf) TEMP. CASE SIZE HEIGHT (mm) VENDOR GRMBR7HKAL V 8 Murata X7R. ±. GRM3MR7HKA88 V 6 X7R. ±. GRM3CR7HKA88. V 6 X7R.6 ±. GRM3CR7H7KAL.7 V 6 X7R.6 ±. UMK36BJ7KL-T.7 V 6 Taiyo Yuden X7R.6 ± = 3.6V s CURRENT (ma) TAIYO YUDEN NR8TM TDK VLCF8T-MR9- TAIYO YUDEN NRTM TDKVLCFAT-MR MURATA LQH3CNK3 TDK VLCFT-MR6 SUMIDA CDRH3D8-NC EPCOS B87-A3-M 39 F3 Figure 3. Effi ciency Comparison of Different Inductors 7

8 APPLICATIONS INFORMATION SCHOTTKY DIODE The has a built-in Schottky diode. The internal schottky saves board space in space constrained applications. In less space sensitive applications, an external schottky diode connected between the node and the node increases efficiency one to two percent. It is important to use a properly rated schottky diode that can handle the peak switch current of the. In addition, the schottky diode must have a breakdown voltage of at least V along with a low forward voltage in order to achieve higher effi ciency. One recommended external schottky diode for the is the Phillips PMEGAEA. OVERVOLTAGE PROTECTION The has an internal open-circuit protection circuit. In the cases of output open circuit, when the s are disconnected from the circuit or the s fail open circuit, V is clamped at V (typ). The will then switch at a very low frequency to minimize input current. The V and input current during output open circuit are shown in the Typical Performance Characteristics. Figure shows the transient response when the s are disconnected. For low DCR inductors, which is usually the case for this application, the peak inrush current can be simplifi ed as follows: I PK VIN 6. = exp L ω r α = L ω = r L C L α ω π where L is the inductance, r is the DCR of the inductor and C is the output capacitance. Table 3 gives inrush peak currents for some component selections. Table 3. Inrush Peak Currents (V) r (Ω) L (µh) C OUT (µf) I P (A) I L ma/div V V/DIV = 3.6V CIRCUIT OF FRONT PAGE APPLICATION INRUSH CURRENT µs/div s DISCONNECTED AT THIS INSTANT Figure. Output Open-Circuit Waveform 39 F The has a built-in Schottky diode. When supply voltage is applied to the pin, an inrush current fl ows through the inductor and the Schottky diode and charges up the voltage. The Schottky diode inside the can sustain a maximum current of A. PROGRAMMING CURRENT The feedback resistor ( ) and the sense voltage (V V ) control the current. The pin controls the sense reference voltage as shown in the Typical Performance Characteristics. For higher than.v, the sense reference is mv, which results in full current. In order to have accurate current, precision resistors are preferred (% is recommended). The formula and table for selection are shown below. mv RSENSE = I 8

9 APPLICATIONS INFORMATION Table. Value Selection for mv Sense I (ma) (Ω) 3.3 DIMMING CONTROL There are three different types of dimming control circuits. The current can be set by modulating the pin with a DC voltage, a filtered PWM signal or directly with a PWM signal. Using a DC Voltage For some applications, the preferred method of brightness control is a variable DC voltage to adjust the current. The pin voltage can be modulated to set the dimming of the string. As the voltage on the pin increases from V to.v, the current increases from to I. As the pin voltage increases beyond.v, it has no effect on the current. The current can be set by: I I mv, when V >. V R SENSE V 6. R SENSE, when V. V < Feedback voltage variation versus control voltage is given in the Typical Performance Characteristics. Using a Filtered PWM Signal A fi ltered PWM signal can be used to control the brightness of the string. The PWM signal is fi ltered (Figure ) by a RC network and fed to the pin. The corner frequency of R, should be much lower than the frequency of the PWM signal. R needs to be much smaller than the internal impedance of the pin which is MΩ (typ). Direct PWM Dimming Changing the forward current fl owing in the s not only changes the intensity of the s, it also changes the color. The chromaticity of the s changes with the change in forward current. Many applications cannot tolerate any shift in the color of the s. Controlling the intensity of the s with a direct PWM signal allows dimming of the s without changing the color. In addition, direct PWM dimming offers a wider dimming range to the user. Dimming the s via a PWM signal essentially involves turning the s on and off at the PWM frequency. The typical human eye has a limit of ~6 frames per second. By increasing the PWM frequency to ~8Hz 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 s can be controlled. The color of the s remains unchanged in this scheme since the current value is either zero or a constant value. Figure 6 shows a Li-Ion powered driver for ten white s. Direct PWM dimming method requires an external NMOS tied between the cathode of the lowest in the string 3V TO V µh Ω.µF PWM khz TYP R k. 39 F V V PWM FREQ k Q Si38 39 F6 Figure. Dimming Control Using a Filtered PWM Signal Figure 6. Li-Ion to Ten White s with Direct PWM Dimming 9

10 APPLICATIONS INFORMATION and ground as shown in Figure 6. A Si38 MOSFET can be used since its source is connected to ground. The PWM signal is applied to the pin of the and the gate of the MOSFET. The PWM signal should traverse between V to V, to ensure proper turn on and off of the driver and the NMOS transistor Q. When the PWM signal goes high, the s are connected to ground and a current of I = mv/ flows through the s. When the PWM signal goes low, the s are disconnected and turn off. The MOSFET ensures that the s quickly turn off without discharging the output capacitor which in turn allows the s to turn on faster. Figure 7 shows the PWM dimming waveforms for the circuit in Figure 6. PWM V/DIV The calculations show that for a Hz signal the dimming range is 83 to. In addition, the minimum PWM duty cycle of.% ensures that the current has enough time to settle to its final value. Figure 8 shows the dimming range achievable for different frequencies with a settling time of µs. PWM DIMMING RANGE PULSING MAY BE VISIBLE I L ma/div PWM DIMMING FREQUENCY (Hz) 39 F8 I ma/div = 3.6V s ms/div Figure 7. Direct PWM Dimming Waveforms 39 F7 The time it takes for the current to reach its programmed value sets the achievable dimming range for a given PWM frequency. For example, the settling time of the current in Figure 7 is approximately µs for a 3.6V input voltage. The achievable dimming range for this application and Hz PWM frequency can be determined using the following method. Example: ƒ = Hz, t = µs t PERIOD SETTLE = = = ƒ. s t Dim Range PERIOD. s = = = 83: t µs SETTLE t µs Min Duty Cycle = SETTLE = t. s =. % PERIOD Duty Cycle Range = %. % at Hz Figure 8. Dimming Range vs Frequency In addition to extending the dimming range, PWM dimming improves the efficiency of the converter for currents below ma. Figure 9 shows the efficiency for traditional analog dimming of the front page application and PWM dimming of the application in Figure PWM DIMMING ANALOG DIMMING CURRENT (ma) = 3.6V s Figure 9. PWM vs Analog Dimming Effi ciency 39 F9

11 APPLICATIONS INFORMATION LOW INPUT VOLTAGE APPLICATIONS The can be used in low input voltage applications. The input supply voltage to the must be.v or higher. However, the inductor can be run off a lower battery voltage. This technique allows the s to be powered off two alkaline cells. Most portable devices have a 3.3V logic supply voltage which can be used to power the. The s can be driven straight from the battery, resulting in higher efficiency. Figure shows six s powered by two AA cells. The battery is connected to the inductor and the chip is powered off a 3.3V logic supply voltage. 3.3V AA CELLS V TO 3.V µh SHUTDOWN AND DIMMING CONTROL Ω.7µF 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 (). Keep the sense voltage pins ( and ) away from the switching node. Place C OUT next to the pin. Always use a ground plane under the switching regulator to minimize interplane coupling. Recommended component placement is shown in Figure. C IN C OUT 39 F : TAIYO YUDEN EMK7BJMA : MURATA GRM3CR7H7KAL : TAIYO YUDEN NR8TM 39 F Figure. Recommended Component Placement Figure. AA Cells to Six White s

12 TYPICAL APPLICATIONS Li-Ion Driver for Ten White s Effi ciency 3V TO V SHUTDOWN AND DIMMING CONTROL µh D *OPTIONAL Ω.µF = 3.6V s NO SCHOTTKY EXTERNAL SCHOTTKY 39 TAa CURRENT (ma) 39 TAb :TAIYO YUDEN EMK7BJMA : MURATA GRM3CR7HKA88 : TAIYO YUDEN NR8TM D: PHILLIPS PMEGAEA Li-Ion Driver for Four White s at ma Effi ciency SHUTDOWN AND DIMMING CONTROL 8 = 3.6V s 3V TO V µh 3.9Ω.7µF :TAIYO YUDEN EMK7BJMA : MURATA GRM3CR7H7KAL : MURATA LQH3CNK3 39 TA3a 6 3 CURRENT (ma) 39 TA3b

13 TYPICAL APPLICATIONS V to Four White s at ma Effi ciency.7µf 9 P V 3V SHUTDOWN AND DIMMING CONTROL C3 Ω : TAIYO YUDEN EMK7BJMA : MURATA GRM3CR7H7KAL C3: MURATA GRMBR7HKAL : TAIYO YUDEN NR8TM 39 TAa µh CURRENT (ma) 39 TAb V to Five White s at ma Effi ciency.7µf 9 P V C3 Ω 9 3V SHUTDOWN AND DIMMING CONTROL 39 TA6a µh : TAIYO YUDEN EMK7BJMA : MURATA GRM3CR7H7KAL C3: MURATA GRMBR7HKAL : TAIYO YUDEN NR8TM CURRENT (ma) 39 TA6b 3

14 TYPICAL APPLICATIONS Li-Ion Driver for Seven White s Conversion Effi ciency 3V TO V µh SHUTDOWN AND DIMMING CONTROL Ω.µF = 3.6V 7 s CURRENT (ma) 39 TA7b : TAIYO YUDEN EMK7BJMA : MURATA GRM3CR7HKA88 : TAIYO YUDEN NR8TM 39 TA7a Li-Ion Driver for Eight White s Conversion Effi ciency 3V TO V µh SHUTDOWN AND DIMMING CONTROL Ω.µF = 3.6V 8 s 6 CURRENT (ma) 39 TA8b : TAIYO YUDEN EMK7BJMA : MURATA GRM3CR7HKA88 : TAIYO YUDEN NR8TM 39 TA8a

15 PACKAGE DESCRIPTION DDB Package 8-Lead Plastic DFN (3mm mm) (Reference LTC DWG # -8-7 Rev B). ±.. ±..6 ±. ( SIDES).7 ±.. ±.. BSC. ±. ( SIDES) PACKAGE OUTLINE RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS 3. ±. ( SIDES) R =. TYP R =. TYP 8. ±. PIN BAR TOP MARK (SEE NOTE 6). REF. ±. ( SIDES).7 ±...6 ±. ( SIDES). ±.. BSC. ±. ( SIDES) BOTTOM VIEW EXPOSED PAD PIN R =. OR. CHAMFER (DDB8) DFN 9 REV B NOTE:. DRAWING CONFORMS TO VERSION (WECD-) IN JEDEC PACKAGE OUTLINE M-9. DRAWING NOT TO SCALE 3. ALL DIMENSIONS ARE IN MILLIMETERS. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED.mm ON ANY SIDE. EXPOSED PAD SHALL BE SOLDER PLATED 6. SHADED AREA IS ONLY A REFERENCE FOR PIN LOCATION ON THE TOP AND BOTTOM OF PACKAGE 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.

16 TYPICAL APPLICATION Li-Ion Driver for Nine White s Conversion Effi ciency SHUTDOWN AND DIMMING CONTROL 8 8 = 3.6V 9 s 3V TO V µh Ω.µF CURRENT (ma) : TAIYO YUDEN EMK7BJMA : MURATA GRM3CR7HKA88 : TAIYO YUDEN NR8TM 39 TA9a 39 TA9b RELATED PARTS PART NUMBER DESCRIPTION COMMENTS LT68 Constant-Current, Constant Voltage.MHz, High Effi ciency Up to 6 White s, :.6V to 8V, V OUT(MAX) = 3V, Boost Regulator I Q =.8mA, I SD < µa, MS Package LT937 Constant-Current,.MHz, High Effi ciency White Boost Regulator Up to White s, :.V to V, V OUT(MAX) = 3V, I Q =.9mA, I SD < µa, ThinSOT TM /SC7 Packages LTC 3 Low Noise, MHz Regulated Charge Pump White Driver Up to 6 White s, :.7V to.v, I Q = 8mA, I SD < µa, MS Package LTC3- Low Noise, MHz Regulated Charge Pump White Driver Up to 6 White s, :.7V to.v, I Q = 8mA, I SD < µa, ThinSOT Package LTC3 Low Noise,.7MHz Regulated Charge Pump White Driver Up to 6 White s, :.7V to.v, I Q = 6.mA, I SD < µa, MS Package LTC3 Low Noise,.MHz Regulated Charge Pump White Driver Up to 8 White s, :.7V to.v, I Q = ma, I SD < µa, MS Package LTC3 High Effi ciency, Multidisplay Controller Up to (Main), (Sub) and RGB, :.8V to.v, I Q = µa, I SD < µa, -Lead QFN Package LT36/LT36A LT366/LT366- LT386 Constant-Current,.MHz/.7MHz, High Effi ciency White Boost Regulator with Integrated Schottky Diode Dual Full Function, MHz Diodes White Step-Up Converter with Built-In Schottkys Dual.3A White Converter with : True Color PWM Dimming Up to 6 White s, :.7V to 6V, V OUT(MAX) = 3V, I Q =.9mA, I SD < µa, ThinSOT Package Up to White s, :.7V to V, V OUT(MAX) = 39V, DFN, TSSOP-6 Packages Drives Up to 6 ma White s. :.V to V, V OUT(MAX) = 36V, DFN, TSSOP Packages LT39.3MHz White Driver with Integrated Schottky Diode Drives Up to 6 s. :.V to V, V OUT(MAX) = 7V, SC7 and DFN Packages LT397 Dual Full Function.3MHz Driver with : True Color PWM Dimming with Integrated Schottky Diodes ThinSOT is a trademark of Linear Technology Corporation Up to White s, :.V to V, V OUT(MAX) = 3V, 3mm mm DFN Package 6 LT 7 PRINTED IN USA Linear Technology Corporation 63 McCarthy Blvd., Milpitas, CA (8) 3-9 FAX: (8) LINEAR TECHNOLOGY CORPORATION 7