FEATURES 4.5V to 55V Input Voltage Range Up to 5mA Current 8mA, 55V Switch Internal Schottky Diode 15μA Supply Current in Shutdown 5μA Supply Current Operating, Not Switching Switching Frequency: 85kHz 2mV Feedback Voltage with ±5% Accuracy Input Performs Dimming and Shutdown 91% Effi ciency (1 s, 5mA) Requires Only Output Capacitor 8-Lead SC7 Package 6-Lead 2mm 2mm DFN Package APPLICATIONS Fixed Signage Traffi c Signs Neon Sign Replacement LT359 48V Buck Mode Driver in SC7 and 2mm x 2mm DFN DESCRIPTION The LT 359 is a fixed frequency buck mode converter specifically designed to drive up to 1 s in series from a 48V DC source. Series connection of the s provides identical currents of up to 5mA, 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 85kHz permits the use of tiny, low profile inductors and capacitors. A single pin performs both shutdown and accurate dimming control. The power switch, Schottky diode and control circuitry are all contained inside a space saving SC7 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. TYPICAL APPLICATION Buck Mode Driver for Ten White s Conversion Effi ciency 1 48V 4Ω LT359 5mA 47μH EFFICIENCY (%) 9 8 7 6. 359 TA1a 5 4 1 2 3 4 5 CURRENT (ma) 359 TA1b 359f 1
LT359 ABSOLUTE MAXIMUM RATINGS (Note 1) Input Voltage ( )....3V to 55V Voltage....3V to 55V Voltage... V to 6.V Voltage... V to 4.V Operating Junction Temperature Range (Note 2)... 4 C to 85 C Maximum Junction Temperature... 125 C Storage Temperature Range... 65 C to 15 C Lead Temperature (Soldering, 1 sec) SC 8 Package Only... 3 C PIN CONFIGURATION TOP VIEW TOP VIEW 1 2 3 7 6 5 4 1 2 3 4 8 7 6 5 DC PACKAGE 6-LEAD (2mm 2mm) PLASTIC DFN T JMAX = 125 C, θ JA = 65 C/W TO 85 C/W, θ JC = 2 C/W EXPOSED PAD (PIN 7) IS, MUST BE SOLDERED TO PCB SC8 PACKAGE 8-LEAD PLASTIC SC7 T JMAX = 125 C, θ JA = 75 C/W TO 95 C/W ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL PART MARKING PACKAGE DESCRIPTION TEMPERATURE RANGE LT359EDC#PBF LT359EDC#TRPBF LCNZ 6-Lead (2mm 2mm) Plastic DFN 4 C to 85 C LT359ESC8#PBF LT359ESC8#TRPBF LCPB 8-Lead Plastic SC7 4 C to 85 C Consult LTC Marketing for parts specifi ed with wider operating temperature ranges. Consult LTC 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/ 2 359f
ELECTRICAL CHARACTERISTICS 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 LT359E is guaranteed to meet performance specifi cations from C to 85 C junction temperature. Specifi cations over the 4 C to 85 C operating junction temperature range are assured by design, characterization and correlation with statistical process controls. LT359 The denotes the specifi cations which apply over the full operating temperature range, otherwise specifi cations are at T A = 25 C, = 48V, V = 3.3V, unless otherwise noted. PARAMETER CONDITIONS MIN TYP MAX UNITS Minimum Operating Voltage 4.5 V Current Sense Voltage ( -V ) 19 2 21 mv Sense Voltage Load Regulation ΔI = 1mA to 5mA 5 mv Quiescent Current ON, No Switching V = 47.7V 5 7 μa Quiescent Current in Shutdown V = V 15 2 μa Switching Frequency 65 85 15 khz Maximum Duty Cycle 9 % Switch Current Limit 8 115 15 ma Switch V CESAT I = 5mA 5 mv Switch Leakage Current V = 48V 1 2 μa V for Full Current 1.5 V V to Shut Down IC 1 mv V to Turn on IC 15 mv Pin Bias Current V = 1V, Current Out of Pin 1 na Pin Bias Current V = 47.8V 9 14 μa LDO Voltage V REG I = 1mA 3.1 3.3 3.5 V LDO Load Regulation ΔI = ma to 1mA 17 mv LDO Current Limit 1.5 ma Schottky Forward Drop I SCHOTTKY = 5mA.8 V Schottky Leakage Current V R = 48V 4 μa 359f 3
LT359 TYPICAL PERFORMANCE CHARACTERISTICS ITCH SATURATION VOLTAGE (V).8.7.6.5.4.3 Switch Saturation Voltage (V CESAT ) Schottky Forward Voltage Drop 25 C 4 C 125 C SCHOTTKY FORWARD DROP (V) 1.2 1.1 1..9.8.7.6.5 4 C 25 C 125 C SHUTDOWN CURRENT (μa) 2 18 16 14 12 Shutdown Quiescent Current vs V = V T A = 25 C.2 2 4 6 8 ITCH CURRENT (ma) 1.4 5 1 15 SCHOTTKY FORWARD CURRENT (ma) 2 1 1 2 3 4 (V) 5 6 359 G1 359 G2 359 G3 SHUTDOWN CURRENT (μa) 2 18 16 14 12 1 5 Shutdown Quiescent Current vs Temperature Quiescent Current Schottky Leakage Current V = V = 48V 25 25 5 75 1 125 TEMPERATURE ( C) 359 G4 QUIESCENT CURRENT (μa) 6 55 5 45 4 V = 3.3V T A = 25 C 1 2 3 4 (V) 5 6 359 G5 SCHOTTKY LEAKAGE CURRENT (μa) 2. 1.5 1..5 5 = 4.5V = 24V = 48V 25 25 5 75 1 125 TEMPERATURE ( C) 359 G6 Switching Waveform Transient Response I L 2mA/DIV 5V/DIV V 5V/DIV V 2V/DIV I L 5mA/DIV 1μs/DIV = 48V I = 5mA 1 WHITE s L = 47μH (COILCRAFT) 359 G7 I 5mA/DIV = 48V I = 5mA 1 BLUE s 4μs/DIV 359 G8 4 359f
TYPICAL PERFORMANCE CHARACTERISTICS LT359 SENSE VOLTAGE ( -V ).25.2.15.1.5 Sense Voltage ( V ) vs V = 48V I = 5mA T A = 25 C ITCHING CURRENT LIMIT (ma) 15 14 13 12 11 1 9 Switching Current Limit vs Duty Cycle T A = 25 C ITCHING CURRENT LIMIT (ma) 15 14 13 12 11 1 9 Switching Current Limit vs Temperature.5 1 1.5 V (V) 2 8 2 4 6 8 1 DUTY CYCLE (%) 8 5 25 25 5 75 1 125 TEMPERATURE ( C) 359 G9 359 G1 359 G11 -V (mv) 26 24 22 2 198 196 Sense Voltage ( V ) Sense Voltage ( V ) vs vs Temperature I = 5mA 1 WHITE s T A = 25 C -V (mv) 26 24 22 2 198 196 ITCHING FREQUENCY (KHz) 1 95 9 85 8 75 Switching Frequency over Temperature = 48V 194 1 2 3 4 5 6 (V) 194 5 25 25 5 75 1 125 TEMPERATURE ( C) 7 5 25 25 5 75 1 125 TEMPERATURE ( C) 359 G12 359 G13 359 G14 3.4 3.35 Internal Regulator Line Regulation T A = 25 C V = V I LOAD = V 3.4 3.35 Internal Regulator Load Regulation T A = 25 C V = V I = V 3.4 3.35 Internal Regulator V REG vs Temperature V = 3.3V I LOAD = 1mA V REG (V) 3.3 V = 3.3V I LOAD = 1mA V REG (V) 3.3 V = 3.3V I = 5mA T REG (V) 3.3 3.25 3.25 3.25 3.2 1 2 3 4 5 6 (V) 3.2.2.4.6.8 1 I LOAD (ma) 3.2 5 25 25 5 75 1 125 TEMPERATURE ( C) 359 G15 359 G16 359 G17 359f 5
+ + + LT359 PIN FUNCTIONS (SC7/DFN) (Pin 1/Pin 3): Switch Pin. Minimize trace area at this pin to minimize EMI. Connect the inductor at this pin. (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. (Pin 5/Pin 1): Dimming and Shutdown Pin. Connect it below 1mV to disable the switcher. As the pin voltage is ramped from V to 1.5V, the feedback voltage ( -V ) ramps from mv to 2mV, controlling the LBD current. VIN V I = (Pin 6/Pin 6): Internally Generated 3.3V Regulated Output Pin. Must be locally bypassed with a. X5R capacitor. (Pin 7/Pin 5): Connection point for the anode of the highest and the sense resistor. (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 48V 6.8Ω REG + EAMP A = 6.25 +. VREF 1.25V START-UP 47μH V OUT PWM R S Q RAMP GENERATOR + ISNS 85kHz OSCILLATOR 359 F1 6 Figure 1. Block Diagram 359f
OPERATION The LT359 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 is pulled higher than 15mV, the switching converter sub-blocks including the oscillator, the PWM comparator and the error amplifi er 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 and V voltage and the bandgap reference. In this manner, the error amplifier sets the correct peak current level in inductor to keep the output in regulation. The pin is used to adjust the reference voltage. The LT359 enters into shutdown when is pulled lower than 1mV. Input Voltage Range The minimum input voltage required to generate a particular output voltage in an LT359 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: V V DC + = D V V + V IN D Where V D is the forward voltage drop of the catch diode (~.8V) and V is the voltage drop of the internal switch at maximum load (~.5V). Given DC MAX =.9, this leads to minimum input voltage of: LT359 The maximum input voltage is limited by the absolute maximum rating of 55V. Pulse-Skipping For strings with a low number of s (1, 2, or 3), the LT359 can drive currents without pulse-skipping as long as the voltage across the and sense resistor is greater than roughly 15% of the input supply voltage. If the 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 current remains regulated on an average basis down to zero. Discontinuous Current Mode The pin, in conjunction with the sense resistor, can be used to program the current as discussed under Applications Information. The LT359 can drive a 1- string at 1mA current operating in continuous conduction mode, using the recommended external components shown in the front page application circuit with the sense resistor equal to 1Ω. As current is further reduced, the regulator enters discontinuous conduction mode. The photo in Figure 2 details circuit operation driving ten s at 2mA load. During the discharge phase, the inductor current reaches zero. 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. The ringing can be damped by application of a 3kΩ resistor across the inductor, although this will degrade efficiency. V 2V/DIV I L 1mA/DIV V IN( MIN) ( V + VD ) = + V V DC MAX D 4ns/DIV = 48V I = 2mA 1 WHITE s L = 47μH (MURATA) 359 F2 Figure 2. Switching Waveforms 359f 7
LT359 APPLICATIONS INFORMATION Inductor Selection A 22μH inductor is recommended for most LT359 applications with < 25V and 47μH is recommended for applications with > 25V. Although small size and high efficiency are major concerns, the inductor should have low core losses at 85kHz 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 VENDOR Coilcraft www.coilcraft.com Sumida www.sumida.com Toko www.tokoam.com Würth Elektronik www.we-online.com Coiltronics www.cooperet.com PART SERIES DO165 LPS412 LPS31 1812FS MSS5131 INDUCTANCE RANGE (μh) (RELEVANT TO THIS PART) 1 TO 68 1 TO 68 1 TO 33 1 TO 68 1 TO 39 DIMENSIONS (mm) 5.4 4.2 1.8 4. 4. 1.2 3. 3..9 5.1 5.1 3.1 CDC4D2 1 TO 68 4.8 4.8 2. LLQ168 LLQ212 WE-PD2 TYPE M WE-PD2 TYPE L 1 TO 27 1 TO 68 1 TO 22 1 to 47 5.2 5.8 4.5 7. 7.8 5. CTX32C 1 to 33 2.5 3.2 2.2 Capacitor Selection The small size of ceramic capacitors make them ideal for LT359 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 input capacitor and a. regulator capacitor are suffi cient for most applications. For the output capacitor, is generally recommended, but if the voltage across the capacitor exceeds 1V, a.47μf capacitor may be used instead. For applications driving one or two s 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 (48) 573-415 www.t-yuden.com AVX (83) 448-9411 www.avxcorp.com Murata (714) 852-21 www.murata.com Kemet (48) 986-424 www.kemet.com Murata www.murata.com LQH32M LQH43M 1 to 56 1 to 68 3.2 2.5 2. 4.5 3.2 2. EFFICIENCY (%) 92 9 88 = 48V 1 s FRONT PAGE APPLICATION CIRCUIT TDK SLF7145-471MR22-PF MURATA QH32CN471K23 MURATA LQH43CN471K3 COILCRAFT LP613-474KLB COILCRAFT 18PS-474KLB COILCRAFT LPS412-474ML 86 84 1 2 3 4 5 CURRENT (ma) 359 F3 Figure 3. Effi ciency Comparison of Different Inductors 8 359f
APPLICATIONS INFORMATION Programming Current The feedback resistor ( in Figure 1) and the sense voltage ( -V ) control the current. I V = IN V The pin controls the sense reference voltage as shown in the Typical Performance Characteristics. For higher than 1.5V, the sense reference is 2mV, which results in full current. In order to have accurate current, precision resistors are preferred (1% is recommended). The formula and table for selection are shown below. mv = 2 I Table 3. Theoretical Value for 2mV Sense I (ma) (Ω) 1 2 2 1 3 6.8 4 5. 5 4. 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..25 LT359 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 1.5V, the current increases from to I. As the pin voltage increases beyond 1.5V, it has no effect on the current. The current can be set by: I = 2mV,when V > 1.5V I = V 6.25,when V < 1.25V 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 string. The PWM signal is fi ltered (Figure 5) by a RC network and fed to the pin. The corner frequency of, should be much lower than the frequency of the PWM signal. needs to be much smaller than the internal impedance in the pin which is 1kΩ. PWM khz TYP 1k LT359.2 359 F5 -V (V).15.1 Figure 5. Dimming Control Using a Filtered PWM Signal.5.5 1. 1.5 V (V) 2. 359 F4 Figure 4. Dimming and Shutdown Using Pin 359f 9
LT359 APPLICATIONS INFORMATION Direct PWM Dimming Changing the forward current flowing 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. 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 6 is approximately 5μs for a 48V input voltage. The achievable dimming range for this application and 1Hz PWM frequency can be determined using the following method. Example: ƒ = 1Hz, t = 5μs t PERIOD SETTLE 1 1 = = = ƒ 1 1. s t Dim Range PERIOD 1. s = = = 2: 1 t 5μs SETTLE t Min Duty Cycle SETTLE 5μs = 1 = t 1. s 1 =.% 5 PERIOD Duty Cycle Range = 1%. 5% at 1Hz The calculations show that for a 1Hz signal the dimming range is 2 to 1. In addition, the minimum PWM duty cycle of.5% ensures that the 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 5μs. PWM 5V/DIV V 2V/DIV 1kHz 1Hz 1kHz I 2mA/DIV = 48V 4 s 2ms/DIV 359 F6 Figure 6. Direct PWM Dimming Waveforms 1 1 1 1 PWM DIMMING RANGE 359 F7 Figure 7. Dimming Range Comparison of Three PWM Frequencies 1 359f
LT359 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 pin. In this manner both analog dimming and direct PWM dimming extend the dimming range for a given application. The color of the s no longer remains constant because the forward current of the changes with the height of the signal. For the ten application described above, the s 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 15mV. The use of both techniques together allows the average current for the ten application to be varied from 5mA down to less than 5μA. Internal Voltage Regulator The LT359 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 LT359. The 3.3V is available even during shutdown. It is required to place a. capacitor from V REG 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 (). Keep the sense voltage pins ( and ) away from the switching node. Place the output capacitor,, next to the pin. Always use a ground plane under the switching regulator to minimize interplane coupling. Recommended component placement is shown in Figure 8. V REG V REG V REG V REG 5 4 1 6 6 7 8 3 2 1 2 3 7 5 4 OUT OUT 359 F8 (a) SC7 Package (b) 2mm 2mm DFN Package Figure 8. Recommended Component Placement 359f 11
LT359 TYPICAL APPLICATIONS 48V Supply for 6 String, 5mA Current Conversion Effi ciency 1 9 48V >1.5V. 4Ω LT359 6 s 5mA 47μH 359 TA2a EFFICIENCY (%) 8 7 6 5 4 1 2 3 4 5 CURRENT (ma) : MURATA LQH32CN221K3 359 TA2b 48V Supply for 5 String, 3mA Current Conversion Effi ciency 1 9 48V >1.5V 6.8Ω LT359 3mA 47μH EFFICIENCY (%) 8 7 6 5. 359 TA3a 4 5 1 15 2 25 3 CURRENT (ma) : MURATA LQH32CN-391 359 TA3b 24V Supply for a 5 String, 3mA Current Conversion Effi ciency 1 9 24V >1.5V 6.8Ω LT359 3mA 22μH EFFICIENCY (%) 8 7 6 5. 359 TA4a 4 5 1 15 2 25 3 CURRENT (ma) : MURATA LQH32CN-221 12 359 TA4b 359f
TYPICAL APPLICATIONS 12V or 24V Supply for a Single, 5mA Current Conversion Effi ciency LT359 2.2μF 8 75 12V OR 24V >1.5V. 4Ω LT359 5mA 22μH 359 TA5a EFFICIENCY (%) 7 65 6 55 5 45 4 12V 24V 1 2 3 4 5 CURRENT (ma) 359 TA5b 48V >1.5V. 48V Supply for Two Strings of 1 s, 25mA Current 4Ω LT359 25mA 25mA 47μH 359 TA6a EFFECIENCY (%) 1 9 8 7 6 5 4 Conversion Effi ciency 5 1 15 2 25 CURRENT (ma) 359 TA6b 12V Supply for a 3 String, 5mA Current 1 Conversion Effi ciency 12V >1.5V. 4Ω LT359 5mA 22μH 359 TA7a EFFICIENCY (%) 9 8 7 6 5 4 1 2 3 4 5 CURRENT (ma) : MURATA LQH32CN-221 359 TA7b 359f 13
LT359 PACKAGE DESCRIPTION DC Package 6-Lead Plastic DFN (2mm 2mm) (Reference LTC DWG # 5-8-173).675 ±.5 R =.115 TYP.56 ±.5 (2 SIDES) 4 6.38 ±.5 2.5 ±.5 1.15 ±.5.61 ±.5 (2 SIDES) PACKAGE PIN 1 BAR OUTLINE TOP MARK (SEE NOTE 6).25 ±.5.5 BSC 1.42 ±.5 (2 SIDES) RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS.2 REF NOTE: 1. DRAWING TO BE MADE A JEDEC PACKAGE OUTLINE M-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.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 2. ±.1 (4 SIDES).75 ±.5..5 PIN 1 CHAMFER OF EXPOSED PAD (DC6) DFN 113 3 1.25 ±.5.5 BSC 1.37 ±.5 (2 SIDES) BOTTOM VIEW EXPOSED PAD 14 359f
LT359 PACKAGE DESCRIPTION SC8 Package 8-Lead Plastic SC7 (Reference LTC DWG # 5-8-1639 Rev Ø).3 MAX.5 REF PIN 8 1.8 2.2 (NOTE 4) 1. REF 2.8 BSC 1.8 REF 1.8 2.4 1.15 1.35 (NOTE 4) INDEX AREA (NOTE 6) PIN 1 GAUGE PLANE.15 BSC RECOMMENDED SOLDER PAD LAYOUT PER IPC CALCULATOR.1.4 1. MAX.5 BSC.8 1..15.27 8 PLCS (NOTE 3)..1 REF.26.46 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.1.18 (NOTE 3) 5. MOLD FLASH SHALL NOT EXCEED.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-7 AND JEDEC MO-23 VARIATION BA SC8 SC7 95 REV Ø 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. 359f 15
LT359 TYPICAL APPLICATION 24V Supply for 6 String, 5mA Current Conversion Effi ciency 1 95 4Ω 5mA 9 24V >1.5V LT359 22μH EFFICIENCY (%) 85 8 75 7. 359 TA8a 65 6 1 2 3 4 5 CURRENT (ma) : MURATA LQH32CN-221 359 TA8b RELATED PARTS PART NUMBER DESCRIPTION COMMENTS LT1932 16 Constant Current, 1.2MHz, High Effi ciency White Boost Regulator : 1.V to 1.V, V OUT(MAX) = 34V, Dimming Analog/PWM, I SD < 1μA, ThinSOT Package LT33 Three Channel Ballaster with PWM Dimming : 3.V to 48.V, Dimming 3,:1 True Color PWM, I SD <5μA, MSOP-1 Package LT3465/A LT3466/-1 Constant Current, 1.2/2.7MHz, High Effi ciency White Boost Regulator with Integrated Schottky Diode Dual Constant Current, 2MHz, High Effi ciency White Boost Regulator with Integrated Schottky Diode : 2.7V to 16.V, V OUT(MAX) = 34V, Dimming Analog/PWM, I SD <1μA, ThinSOT Package : 2.7V to 24.V, V OUT(MAX) = 4V, Dimming 5mA, I SD <16μA, 3mm 3mm DFN-1 LT3474 36V, 1A (I ), 2MHz,Step-Down Driver : 4.V to 36V, V OUT(MAX) = 13.5V, Dimming 4:1 True Color PWM, I SD <1μA, TSSOP16E Package LT3475 Dual 1.5A(I ), 36V, 2MHz, Step-Down Driver : 4.V to 36V, V OUT(MAX) = 13.5V, Dimming 3,:1 True Color PWM, I SD <1μA, TSSOP2E Package LT3476 Quad Output 1.5A, 2MHz High Current Driver with 1,:1 Dimming : 2.8V to 16.V, V OUT(MAX) = 36.V, Dimming 1,:1 True Color PWM, I SD <1μA, 5mm 7mm QFN-1 LT3478/-1 4.5A, 2MHz High Current Driver with 3,:1 Dimming : 2.8V to 36.V, V OUT(MAX) = 4.V, Dimming 1,:1 True Color PWM, I SD <1μA, 5mm 7mm QFN-1 LT3486 Dual 1.3A, 2MHz High Current Driver : 2.5V to 24.V, V OUT(MAX) = 36.V, Dimming 1,:1 True Color PWM, I SD <1μA, 5mm 3mm DFN, TSSOP-16E Package LT3491 Constant Current, 2.3MHz, High Effi ciency White Boost Regulator with Integrated Schottky Diode LT3496 Triple Output 75mA, 2.1 MHz High Current Driver with 3,:1 Dimming LT3497 Dual 2.3MHz, Full Function Driver with Integrated Schottkys and 25:1 True Color PWM Dimming : 2.5V to 12.V, V OUT(MAX) = 27V, Dimming 3:1 True Color PWM, I SD <8μA, 2mm 2mm DFN-6, SC7 Package : 3.V to 3.V, V OUT(MAX) = 4., Dimming 3,:1 True Color PWM, I SD <1μA, 4mm 5mm QFN-28 : 2.5V to 1.V, V OUT(MAX) = 32, Dimming 25:1 True Color PWM, I SD <12μA, 2mm 3mm DFN-1 LT3498 2mA Driver and O Driver Integrated Schottkys : 2.5 to 12.V, V OUT(MAX) = 32, Dimming Analog/PWM, I SD <8.5μA, 2mm 3mm DFN-12 LT3517 1.3A, 2.5MHz High Current Driver with 3,:1 Dimming : 3.V to 3.V, Dimming 3,:1 True Color PWM, I SD <1μA, 4mm 4mm QFN-16 LT3518 2.3A, 2.5MHz High Current Driver with 3,:1 Dimming : 3.V to 3.V, Dimming 3,:1 True Color PWM, I SD <1μA, 4mm 4mm QFN-16 LT3591 Constant Current, 1MHz, High Effi ciency White Boost Regulator with Integrated Schottky Diode and 8:1 True Color PWM Dimming ThinSOT and True Color PWM are trademarks of Linear Technology Corporation. : 2.5V to 12.V, V OUT(MAX) = 4, Dimming 8:1 True Color PWM, I SD <9μA, 2mm 3mm DFN-8 LT 77 PRINTED IN USA Linear Technology Corporation 163 McCarthy Blvd., Milpitas, CA 9535-7417 (48) 432-19 FAX: (48) 434-57 www.linear.com LINEAR TECHNOLOGY CORPORATION 27 359f