LT1932 Constant-Current DC/DC LED Driver in ThinSOT FEATURES DESCRIPTIOU n Up to 80% Efficiency The LT®1932 is a fixed frequency step-up DC/DC converter n Inherently Matched LED Current designed to operate as a constant-current source. Be- n Adjustable Control of LED Current cause it directly regulates output current, the LT1932 is n Drives Five White LEDs from 2V ideal for driving light emitting diodes (LEDs) whose light n Drives Six White LEDs from 2.7V intensity is proportional to the current passing through n Drives Eight White LEDs from 3V them, not the voltage across their terminals. n Disconnects LEDs In Shutdown With an input voltage range of 1V to 10V, the device works n 1.2MHz Fixed Frequency Switching from a variety of input sources. The LT1932 accurately n Uses Tiny Ceramic Capacitors regulates LED current even when the input voltage is n Uses Tiny 1mm-Tall Inductors higher than the LED voltage, greatly simplifying battery- n Regulates Current Even When V > V IN OUT powered designs. A single external resistor sets LED n Operates with V as Low as 1V IN current between 5mA and 40mA, which can then be easily n Low Profile (1mm) ThinSOTTM Package adjusted using either a DC voltage or a pulse width APPLICATIOU S modulated (PWM) signal. When the LT1932 is placed in shutdown, the LEDs are disconnected fmroAm fo trh teh eo uetnptuirte,ensuring a quiescent current of under 1 n Cellular Telephones circuit. The device’s 1.2MHz switching frequency permits n Handheld Computers the use of tiny, low profile chip inductors and capacitors to n Digital Cameras minimize footprint and cost in space-conscious portable n Portable MP3 Players applications. n Pagers , LTC and LT are registered trademarks of Linear Technology Corporation. ThinSOT is a trademark of Linear Technology Corporation. TYPICAL APPLICATIOU Li-Ion Driver for Four White LEDs Efficiency L1 85 6.8µH D1 2.7V TO 4V.2IVN 80 VIN = 4.2V C4.17µF 6 1 Y (%) 75 VIN = 2.7V VIN SW NC E LT1932 CI DIMMPWINMG 5 SHDN LED 3 C1µ2F EFFI 65 CONTROL RSET GND 15mA 60 4 2 RSET 1.50k 55 0 5 10 15 20 C1: TAIYO YUDEN JMK212BJ475 LED CURRENT (mA) 1932 TA01 C2: TAIYO YUDEN EMK212BJ105 1932 TA02 D1:ZETEX ZHCS400 L1: SUMIDA CLQ4D106R8 OR PANASONIC ELJEA6R8 1932f 1

LT1932 ABSOLUTE W AXIW UW RATIU GS PACKAGE/ORDER IU FORW ATIOU (Note 1) V Voltage ............................................................. 10V ORDER PART IN SHDN Voltage......................................................... 10V TOP VIEW NUMBER SW Voltage............................................................. 36V SW 1 6 VIN LT1932ES6 LED Voltage............................................................. 36V GND 2 5 SHDN RSET Voltage............................................................. 1V LED 3 4 RSET Junction Temperature.......................................... 125(cid:176) C S6 PART MARKING S6 PACKAGE Operating Temperature Range (Note 2).. –40(cid:176) C to 85(cid:176) C 6-LEAD PLASTIC SOT-23 LTST Storage Temperature Range................. –65(cid:176) C to 150(cid:176) C TJMAX = 125(cid:176)C, q JA = 250(cid:176)C/W Lead Temperature (Soldering, 10 sec)..................300(cid:176) C Consult LTC Marketing for parts specified with wider operating temperature ranges. ELECTRICAL CHARACTERISTICS The l denotes specifications that apply over the full operating temperature range, otherwise specifications are at T = 25(cid:176) C. V = 1.2V, V = 1.2V, unless otherwise noted. A IN SHDN PARAMETER CONDITIONS MIN TYP MAX UNITS Minimum Input Voltage 1 V Quiescent Current V = 0.2V 1.2 1.6 mA RSET V = 0V 0.1 1.0 m A SHDN R Pin Voltage R = 1.50k 100 mV SET SET LED Pin Voltage R = 1.50k, V < V (Figure 1) 120 180 mV SET IN OUT LED Pin Current R = 562W , V = 1.5V 33 38 45 mA SET IN R = 750W , V = 1.2V 25 30 36 mA SET IN R = 1.50k, V = 1.2V 12.5 15 17.5 mA SET IN R = 4.53k, V = 1.2V 5 mA SET IN LED Pin Current Temperature Coefficient I = 15mA –0.02 mA/(cid:176) C LED Switching Frequency V = 1V 0.8 1.2 1.6 MHz IN Maximum Switch Duty Cycle l 90 95 % Switch Current Limit 400 550 780 mA Switch V I = 300mA 150 200 mV CESAT SW SHDN Pin Current V = 0V 0 0.1 m A SHDN V = 2V 15 30 m A SHDN Start-Up Threshold (SHDN Pin) 0.85 V Shutdown Threshold (SHDN Pin) 0.25 V Switch Leakage Current Switch Off, V = 5V 0.01 5 m A SW Note 1: Absolute Maximum Ratings are those values beyond which the life of a device may be impaired. Note 2: The LT1932E is guaranteed to meet specifications from 0(cid:176) C to 70(cid:176) C. Specifications over the –40(cid:176) C to 85(cid:176) C operating temperature range are assured by design, characterization and correlation with statistical process controls. 1932f 2

LT1932 TYPICAL PERFORW AU CE CHARACTERISTICS Switch Saturation Voltage (V ) Switch Current Limit Switching Frequency CESAT 400 700 2.0 1.8 GE (mV) 330500 TJ = 125°C 600 VIN = 10V VIN = 1.2V MHz) 1.6 TION VOLTA 220500 TJ = 25°C RRENT (mA) 450000 REQUENCY ( 111...042 VVIINN == 11.02VV CH SATURA 110500 TJ = –50°C PEAK CU 320000 WITCHING F 000...684 SWIT 50 100 S 0.2 0 0 0 0 100 200 300 400 500 600 –50 –25 0 25 50 75 100 125 –50 –25 0 25 50 75 100 125 SWITCH CURRENT (mA) TEMPERATURE (°C) TEMPERATURE (°C) 1932 G01 1932 G02 1932 G03 LED Pin Voltage LED Current LED Current 400 50 50 45 45 350 RSET = 562Ω RSET = 562Ω 40 40 ED PIN VOLTAGE (mV) 213205050000 TJ = 25°CTJ = 125°C TJ = –50°C LED CURRENT (mA) 3232150055 RRSSEETT == 715.500Ωk LED CURRENT (mA) 3232150055 RRSSEETT == 715.500Ωk L 100 10 10 50 RSET = 4.53k RSET = 4.53k 5 5 0 0 0 0 5 10 15 20 25 30 35 40 –50 –25 0 25 50 75 100 125 0 2 4 6 8 10 LED CURRENT (mA) TEMPERATURE (°C) INPUT VOLTAGE (V) 1932 G04 1932 G05 1932 G06 Quiescent Current SHDN Pin Current Switching Waveforms 2.00 50 1.75 45 TJ = –50°C 10V/VDSIWV mA)1.50 40 IL1 ESCENT CURRENT (110...027055 VVIINN == 11.02VV SHDN PIN CURRENT 3213250505 TJ T=J 1 =2 52°5C°C AC2 021C000OmmmUAVAPV///LIDDDOLEUEIIIDVVVDTVIN = 3V 0.5m s/DIV 1093 G09 UI0.50 4 WHITE LEDs Q 10 ILED = 15mA 0.25 CIRCUIT ON FIRST PAGE 5 OF THIS DATA SHEET 0 0 –50 –25 0 25 50 75 100 125 0 2 4 6 8 10 TEMPERATURE (°C) SHDN PIN VOLTAGE (V) 1932 G07 1932 G08 1932f 3

LT1932 PIU FUU CTIOU S SW (Pin 1): Switch Pin. This is the collector of the internal R (Pin 4): A resistor between this pin and ground SET NPN power switch. Minimize the metal trace area con- programs the LED current (that flows into the LED pin). nected to this pin to minimize EMI. This pin is also used to provide LED dimming. GND (Pin 2): Ground Pin. Tie this pin directly to local SHDN (Pin 5): Shutdown Pin. Tie this pin higher than ground plane. 0.85V to turn on the LT1932; tie below 0.25V to turn it off. LED (Pin 3): LED Pin. This is the collector of the internal V (Pin 6): Input Supply Pin. Bypass this pin with a IN NPN LED switch. Connect the cathode of the bottom LED capacitor to ground as close to the device as possible. to this pin. BLOCK DIAGRAW D1 L1 VOUT VIN C1 SHDN VIN SW C2 5 6 1 DRIVER Q1 + 0.04Ω · 5 – LED + 3 1.2MHz S OSCILLATOR + ILED DRIVER Q2 S + Q R A2 – – A1 + LED CURRENT REFERENCE 2 4 1932 F01 GND ISET RSET RSET Figure 1. LT1932 Block Diagram OPERATIOU The LT1932 uses a constant frequency, current mode power switch. In this manner, A1 sets the correct peak control scheme to regulate the output current, I . current level to keep the LED current in regulation. If A1’s LED Operation can be best understood by referring to the output increases, more current is delivered to the output; block diagram in Figure 1. At the start of each oscillator if it decreases, less current is delivered. A1 senses the cycle, the SR latch is set, turning on power switch Q1. The LED current in switch Q2 and compares it to the current signal at the noninverting input of the PWM comparator reference, which is programmed using resistor R . The SET A2 is proportional to the switch current, summed to- R pin is regulated to 100mV and the output current, SET gether with a portion of the oscillator ramp. When this I , is regulated to 225 • I . Pulling the R pin higher LED SET SET signal reaches the level set by the output of error amplifier than 100mV will pull down the output of A1, turning off A1, comparator A2 resets the latch and turns off the power switch Q1 and LED switch Q2. 1932f 4

LT1932 APPLICATIOU S IU FORW ATIOU Inductor Selection efficiency by up to 12% over the smaller, thinner ones. Keep this in mind when choosing an inductor. Several inductors that work well with the LT1932 are listed in Table 1. Many different sizes and shapes are available. The value of inductance also plays an important role in the Consult each manufacturer for more detailed information overall system efficiency. While a 1m H inductor will have and for their entire selection of related parts. As core a lower DCR and a higher current rating than the 6.8m H losses at 1.2MHz are much lower for ferrite cores that for version of the same part, lower inductance will result in the cheaper powdered-iron ones, ferrite core inductors higher peak currents in the switch, inductor and diode. should be used to obtain the best efficiency. Choose an Efficiency will suffer if inductance is too small. Figure 3 inductor that can handle at least 0.5A and ensure that the shows the efficiency of the Typical Application on the front inductor has a low DCR (copper wire resistance) to mini- page of this data sheet, with several different values of the mize I2R power losses. A 4.7m H or 6.8m H inductor will be same type of inductor (Panasonic ELJEA). The smaller a good choice for most LT1932 designs. values give an efficiency 3% to 5% lower than the 6.8m H value. Table 1. Recommended Inductors MAX MAX L DCR HEIGHT 85 PART (m H) (mW ) (mm) VENDOR PANASONIC 80 ELJEA6R8 ELJEA4R7 4.7 180 2.2 Panasonic SUMIDA ELJEA6R8 6.8 250 2.2 (714) 373-7334 CLQ4D10-6R8 LQH3C4R7M24 4.7 260 2.2 wMwurwa.tpaanasonic.com NCY (%) 7705 CMSDU4DM0ID6-A6R8 E LQH3C100M24 10 300 2.2 (814) 237-1431 CI FI www.murata.com EF 65 TAIYO YUDEN LB2016B6R8 LB2016B4R7 4.7 250 1.6 Taiyo Yuden VIN = 3.6V 60 4 WHITE LEDs LB2016B100 6.8 350 1.6 (408) 573-4150 TAIYO YUDEN ALL ARE 10µH www.t-yuden.com LB2012B6R8 INDUCTORS 55 CMD4D06-4R7 4.7 216 0.8 Sumida 0 5 10 15 20 CMD4D06-6R8 6.8 296 0.8 (847) 956-0666 LED CURRENT (mA) CLQ4D10-4R7 4.7 162 1.2 www.sumida.com 1932 F02 CLQ4D10-6R8 6.8 195 1.2 Figure 2. Efficiency for Several Different Inductor Types Inductor Efficiency Considerations 85 Many applications have thickness requirements that re- 80 strict component heights to 1mm or 2mm. There are 2mm 6.8µH tall inductors currently available that provide a low DCR and low core losses that help provide good overall effi- Y (%) 75 42.72µµHH 2.2µH C ciency. Inductors with a height of 1mm (and less) are N 70 E CI becoming more common, and a few companies have FI F E 65 introduced chip inductors that are not only thin, but have VIN = 3.6V a very small footprint as well. While these smaller induc- 60 4 WHITE LEDs PANASONIC ELJEA tors will be a necessity in some designs, their smaller size INDUCTORS 55 gives higher DCR and core losses, resulting in lower 0 5 10 15 20 efficiencies. Figure 2 shows efficiency for the Typical LED CURRENT (mA) 1932 F03 Application circuit on the front page of this data sheet, with several different inductors. The larger devices improve Figure 3. Efficiency for Several Different Inductor Values 1932f 5

LT1932 APPLICATIOU S IU FORW ATIOU Capacitor Selection turned off (typically less than one-third the time), so a 0.4A or 0.5A diode will be sufficient for most designs. Low ESR (equivalent series resistance) capacitors should be used at the output to minimize the output ripple Table 3. Recommended Schottky Diodes voltage. Because they have an extremely low ESR and are PART VENDOR available in very small packages, multilayer ceramic ca- MBR0520 ON Semiconductor pacitors are an excellent choice. X5R and X7R type MBR0530 (800) 282-9855 MBR0540 www.onsemi.com capacitors are preferred because they retain their capaci- ZHCS400 Zetex tance over wider voltage and temperature ranges than ZHCS500 (631) 543-7100 other types such as Y5V or Z5U. A 1m F or 2.2m F output www.zetex.com capacitor is sufficient for most applications. Always use a capacitor with a sufficient voltage rating. Ceramic capaci- Programming LED Current tors do not need to be derated (do not buy a capacitor with a rating twice what your application needs). A 16V ce- The LED current is programmed with a single resistor ramic capacitor is good to more than 16V, unlike a 16V connected to the R pin (see Figure 1). The R pin is SET SET tantalum, which may be good to only 8V when used in internally regulated to 100mV, which sets the current certain applications. Low profile ceramic capacitors with flowing out of this pin, I , equal to 100mV/R . The SET SET a 1mm maximum thickness are available for designs LT1932 regulates the current into the LED pin, I , to 225 LED having strict height requirements. times the value of I . For the best accuracy, a 1% (or SET better) resistor value should be used. Table 4 shows Ceramic capacitors also make a good choice for the input several typical 1% R values. For other LED current decoupling capacitor, which should be placed as close as SET values, use the following equation to choose R . possible to the LT1932. A 2.2m F or 4.7m F input capacitor SET is sufficient for most applications. Table 2 shows a list of (cid:230) 0.1V(cid:246) several ceramic capacitor manufacturers. Consult the R =225•(cid:231) (cid:247) SET Ł I ł manufacturers for detailed information on their entire LED selection of ceramic parts. Table 4. R Resistor Values SET Table 2. Recommended Ceramic Capacitor Manufacturers I (mA) R VALUE LED SET VENDOR PHONE URL 40 562W Taiyo Yuden (408) 573-4150 www.t-yuden.com 30 750W Murata (814) 237-1431 www.murata.com 20 1.13k Kemet (408) 986-0424 www.kemet.com 15 1.50k 10 2.26k Diode Selection 5 4.53k Schottky diodes, with their low forward voltage drop and Most white LEDs are driven at maximum currents of 15mA fast switching speed, are the ideal choice for LT1932 to 20mA. Some higher power designs will use two parallel applications. Table 3 shows several different Schottky strings of LEDs for greater light output, resulting in 30mA diodes that work well with the LT1932. Make sure that the to 40mA (two strings of 15mA to 20mA) flowing into the diode has a voltage rating greater than the output voltage. LED pin. The diode conducts current only when the power switch is 1932f 6

LT1932 APPLICATIOU S IU FORW ATIOU Open-Circuit Protection If the R pin is used, increasing the duty cycle will SET decrease the brightness. Using this method, the LEDs are For applications where the string of LEDs can be discon- dimmed using R and turned off completely using nected or could potentially become an open circuit, a zener SET SHDN. If the R pin is used to provide PWM dimming, diode can be added across the LEDs to protect the LT1932 SET the approximate value of R should be (where V is (see Figure 4). If the device is turned on without the LEDs PWM MAX the “high” value of the PWM signal): present, no current feedback signal is provided to the LED pin. The LT1932 will then switch at its maximum duty (cid:230) V (cid:246) cycle, generating an output voltage 10 to 15 times greater R =R •(cid:231) MAX –1(cid:247) PWM SET Ł ł 0.15V than the input voltage. Without the zener, the SW pin could see more than 36V and exceed its maximum rating. The In addition to providing the widest dimming range, PWM zener voltage should be larger than the maximum forward brightness control also ensures the “purest” white LED voltage of the LED string. color over the entire dimming range. The true color of a white LED changes with operating current, and is the L1 6.8µH D1 “purest” white at a specific forward current, usually 15mA VIN or 20mA. If the LED current is less than or more than this value, the emitted light becomes more blue. For color 6 1 24V LCDs, this often results in a noticeable and undesirable VIN SW blue tint to the display. LT1932 C1 5 3 C2 When a PWM control signal is used to drive the SHDN pin 4.7µF SHDN LED 1µF of the LT1932 (see Figure 6), the LEDs are turned off and RSET GND 15mA on at the PWM frequency. The current through them 4 2 RSET alternates between full current and zero current, so the 1.50k average current changes with duty cycle. This ensures 1932 F04 that when the LEDs are on, they can be driven at the appropriate current to give the purest white light. Figure Figure 4. LED Driver with Open-Circuit Protection 5 shows the LED current when a 5kHz PWM dimming control signal is used with the LT1932. The LED current Dimming Using a PWM Signal waveform cleanly tracks the PWM control signal with no PWM brightness control provides the widest dimming delays, so the LED brightness varies linearly with the range (greater than 20:1) by pulsing the LEDs on and off PWM duty cycle. using the control signal. The LEDs operate at either zero or full current, but their average current changes with the PWM signal duty cycle. Typically, a 5kHz to 40kHz PWM signal is used. PWM dimming with the LT1932 can be VPWM 2V/DIV accomplished two different ways (see Figure 6). The SHDN pin can be driven directly or a resistor can be added to drive the R pin. SET ILED If the SHDN pin is used, increasing the duty cycle will 10mA/DIV increase the LED brightness. Using this method, the LEDs can be dimmed and turned off completely using the same 50m s/DIV 1932 F05 control signal. A 0% duty cycle signal will turn off the LT1932, reducing the total quiescent current to zero. Figure 5. PWM Dimming Using the SHDN Pin 1932f 7

LT1932 APPLICATIOU S IU FORW ATIOU Dimming Using a Filtered PWM Signal of the R pin, thus reducing the LED current. Choose the SET R value as shown below where V is the maximum While the direct PWM method provides the widest dim- ADJ MAX DC control voltage, I is the current programmed ming range and the purest white light output, it causes the LED(MAX) by R , and I is the minimum value of I (when LT1932 to enter into Burst Mode® operation. This opera- SET LED(MIN) LED the DC control voltage is at V ). tion may be undesirable for some systems, as it may MAX reflect some noise to the input source at the PWM fre- (cid:230) (cid:246) V –0.1V quency. The solution is to filter the control signal by adding RADJ =225•(cid:231) MAX (cid:247) a 10k resistor and a 0.1m F capacitor as shown in Figure 6, Ł ILED(MAX) –ILED(MIN)ł converting the PWM to a DC level before it reaches the RSET pin. The 10k resistor minimizes the capacitance seen Regulating LED Current when VIN > VOUT by the R pin. SET The LT1932 contains special circuitry that enables it to regulate the LED current even when the input voltage is Dimming Using a Logic Signal higher than the output voltage. When V is less than V , IN OUT For applications that need to adjust the LED brightness in the internal NPN LED switch (transistor Q2 in Figure 1) is discrete steps, a logic signal can be used as shown in saturated to provide a lower power loss. When V is IN Figure 6. R sets the minimum LED current value (when MIN greater than V , the NPN LED switch comes out of OUT the NMOS is off): saturation to keep the LED current in regulation. (cid:230) (cid:246) 0.1V RMIN =225•(cid:231) (cid:247) Soft-Start/Controlling Inrush Current Ł I ł LED(MIN) For many applications, it is necessary to minimize the inrush current at start-up. When first turned on and the R sets how much the LED current is increased when INCR LED current is zero, the LT1932 will initially command the the NMOS is turned on: maximum switch current of 500mA to 600mA, which may (cid:230) (cid:246) give an inrush current too high for some applications. A 0.1V RINCR =225•(cid:231) (cid:247) soft-start circuit (Figure 7) can be added to significantly Ł I ł LED(INCREASE) reduce the start-up current spike. Figure 8 shows that without soft-start the input current reaches almost 600mA. Dimming Using a DC Voltage Figure 9 shows that when the soft-start circuit is added, the input current has only a brief 300mA spike, and on For some applications, the preferred method of brightness average does not exceed 100mA. control uses a variable DC voltage to adjust the LED current. As the DC voltage is increased, current flows through R into R , reducing the current flowing out ADJ SET Burst Mode is a registered trademark of Linear Technology Corporation. LT1932 LT1932 LT1932 LT1932 LT1932 SHDN RSET RSET RSET RSET 5 4 RPWM 4 10k RPWM 4 RADJ 4 RINCR PWM PWM PWM VDC LOGIC RSET RSET 0.1µF RSET RMIN SIGNAL 1932 F06 PWM PWM FILTERED PWM DC VOLTAGE LOGIC Figure 6. Five Methods of LED Dimming 1932f 8

LT1932 APPLICATIOU S IU FORW ATIOU L1 IIN 6.8µH D1 VOUT VIN C3 0.047µF C1 6 1 4.7µF Q1 VIN SW 2N3904 LT1932 C2 5 3 1µF SHDN LED R1 RSET GND 1.5k 4 2 RSET 1.50k SOFT-START 1932 F07 CIRCUIT Figure 7. Soft-Start Circuit for the LT1932 VOUT VOUT 5V/DIV 5V/DIV IIN 200mA/DIV IIN 200mA/DIV 100m s/DIV 1932 F08 100m s/DIV 1932 F09 Figure 8. Input Current at Start-Up Without Soft-Start Figure 9. Input Current at Start-Up with Soft-Start Board Layout Considerations As with all switching regulators, careful attention must be L1 C1 D1 paid to the PCB board layout and component placement. To maximize efficiency, switch rise and fall times are made as short as possible. To prevent radiation and high fre- C2 1 6 VIN quency resonance problems, proper layout of the high 2 5 SHDN frequency switching path is essential. Minimize the length 3 4 and area of all traces connected to the SW pin and always GND use a ground plane under the switching regulator to RSET minimize interplane coupling. The signal path including DIMMING CONTROL the switch, output diode D1 and output capacitor C2, 1932 F10 contains nanosecond rise and fall times and should be Figure 10. Recommended Component Placement kept as short as possible. In addition, the ground connec- tion for the R resistor should be tied directly to the GND SET pin and not be shared with any other component, ensuring a clean, noise-free connection. Recommended compo- nent placement is shown in Figure 10. 1932f 9

LT1932 TYPICAL APPLICATIOU S Single Cell Driver for One White LED Efficiency L1 80 4.7µH D1 VIN 1V TO 1.5V 75 VIN = 1.5V 6 1 VIN SW Y (%) 70 VIN = 1.1V LT1932 C N 65 C4.17µF 5 SHDN LED 3 C4.27µF FICIE RSET GND 15mA EF 60 4 2 2.5V PWM 24.9k DIMMING 55 CONTROL RSET 1.50k 50 0 2.5 5 7.5 10 12.5 15 C1, C2: TAIYO YUDEN JMK212BJ475 (408) 573-4150 LED CURRENT (mA) 1932 TA03a D1: ZETEX ZHCS400 (631) 543-7100 L1: MURATA LQH3C4R7M24 (814) 237-1431 1932 TA03b Single Cell Driver for Two White LEDs Efficiency L1 4.7µH D1 80 VIN 1V TO 1.5V 75 VIN = 1.5V 6 1 VIN SW %) 70 VIN = 1.1V LT1932 Y ( C C1 5 3 C2 N 65 4.7µF SHDN LED 2.2µF CIE RSET GND 15mA EFFI 60 4 2 2.5V PWM 24.9k DIMMING 55 CONTROL RSET 1.50k 50 0 2.5 5 7.5 10 12.5 15 C1: TAIYO YUDEN JMK212BJ475 (408) 573-4150 C2: TAIYO YUDEN LMK212BJ225 (408) 573-4150 1932 TA04a LED CURRENT (mA) D1: ZETEX ZHCS400 (631) 543-7100 1932 TA04b L1: MURATA LQH3C4R7M24 (814) 237-1431 1932f 10

LT1932 TYPICAL APPLICATIOU S 2-Cell Driver for Two White LEDs Efficiency L1 85 4.7µH D1 VIN 1.8V TO 3V 80 VIN = 3V 6 1 VIN SW Y (%) 75 VIN = 1.8V LT1932 NC 70 C4.17µF 5 SHDN LED 3 C2.22µF FICIE RSET GND 15mA EF 65 4 2 2.5V DC 60.4k 60 DIMMING CONTROL RSET 1.50k 55 0 5 10 15 20 C1: TAIYO YUDEN JMK212BJ475 (408) 573-4150 LED CURRENT (mA) 1932 TA15a C2: TAIYO YUDEN LMK212BJ225 (408) 573-4150 1932 TA15b D1: ZETEX ZHCS400 (631) 543-7100 L1: MURATA LQH3C4R7M24 (814) 237-1431 2-Cell Driver for Three White LEDs Efficiency L1 4.7µH D1 85 VIN 1.8V TO 3V 80 6 1 VIN = 3V VIN SW %) 75 LT1932 Y ( VIN = 1.8V C C4.17µF 5 SHDN LED 3 C2.22µF CIEN 70 RSET GND 15mA EFFI 65 4 2 2.5V DC 60.4k DIMMING 60 CONTROL RSET 1.50k 55 0 5 10 15 20 C1: TAIYO YUDEN JMK212BJ475 (408) 573-4150 1932 TA06a LED CURRENT (mA) C2: TAIYO YUDEN EMK316BJ225 (408) 573-4150 D1: ZETEX ZHCS400 (631) 543-7100 1932 TA06b L1: MURATA LQH3C4R7M24 (814) 237-1431 1932f 11

LT1932 TYPICAL APPLICATIOU S 2-Cell Driver for Four White LEDs Efficiency L1 85 4.7µH D1 VIN 1.8V TO 3V 80 VIN = 3V C1 6 1 %) 75 4.7µF VIN SW CY ( VIN = 1.8V N 70 E LT1932 CI PWM 5 3 C2 FFI DIMMING SHDN LED 1µF E 65 CONTROL RSET GND 15mA 4 2 60 RSET 1.50k 55 0 5 10 15 20 C1: TAIYO YUDEN JMK212BJ475 (408) 573-4150 1932 TA07a LED CURRENT (mA) C2: TAIYO YUDEN EMK212BJ105 (408) 573-4150 1932 TA07b D1: ZETEX ZHCS400 (631) 543-7100 L1: MURATA LQH3C4R7M24 (814) 237-1431 2-Cell Driver for Five White LEDs Efficiency L1 85 4.7µH D1 VIN 2V TO 3V 80 C4.17µF VIN6 SW1 Y (%) 75 VIN = 3V LT1932 NC 70 CDOIMNMTPRWINOMGL 5 SRHSDETN GNLEDD 3 C1µ2F EFFICIE 65 VIN = 2V 4 2 60 RSET 1.50k 15mA 55 0 5 10 15 20 C1: TAIYO YUDEN JMK212BJ475 (408) 573-4150 LED CURRENT (mA) 1932 TA05a C2: TAIYO YUDEN TMK316BJ105 (408) 573-4150 1932 TA05b D1: ZETEX ZHCS400 (631) 543-7100 L1: MURATA LQH3C4R7M24 (814) 237-1431 1932f 12

LT1932 TYPICAL APPLICATIOU S Li-Ion Driver for Two White LEDs Efficiency 6.L81µH D1 85 VIN 2.7V TO 4.2V 80 VIN = 4.2V 6 1 VIN SW %) 75 VIN = 2.7V LT1932 Y ( C C4.17µF 5 SRHSDETN GNLEDD 3 15mA C2.22µF EFFICIEN 6750 4 2 3.3V PWM 31.6k DIMMING 60 CONTROL RSET 1.50k 55 0 5 10 15 20 C1: TAIYO YUDEN JMK212BJ475 (408) 573-4150 1932 TA08a LED CURRENT (mA) C2: TAIYO YUDEN LMK212BJ225 (408) 573-4150 D1: ZETEX ZHCS400 (631) 543-7100 1932 TA08b L1: PANASONIC ELJEA6R8 (714) 373-7334 Li-Ion Driver for Three White LEDs Efficiency L1 85 6.8µH D1 2.7V TO 4V.2IVN 80 VIN = 4.2V 6 1 VIN = 2.7V VIN SW %) 75 Y ( LT1932 C N 70 C4.17µF 5 SHDN LED 3 C2.22µF FICIE RSET GND 15mA EF 65 4 2 3.3V PWM 31.6k DIMMING 60 CONTROL RSET 1.50k 55 0 5 10 15 20 C1: TAIYO YUDEN JMK212BJ475 (408) 573-4150 LED CURRENT (mA) 1932 TA09a C2: TAIYO YUDEN EMK316BJ225 (408) 573-4150 D1: ZETEX ZHCS400 (631) 543-7100 1932 TA09b L1: PANASONIC ELJEA6R8 (714) 373-7334 1932f 13

LT1932 TYPICAL APPLICATIOU S Li-Ion Driver for Four White LEDs Efficiency L1 85 6.8µH D1 2.7V TO 4V.2IVN 80 VIN = 4.2V C1 6 1 %) 75 VIN = 2.7V 4.7µF VIN SW NCY ( 70 E LT1932 CI DIMMPWINMG 5 SHDN LED 3 C1µ2F EFFI 65 CONTROL RSET GND 15mA 60 4 2 RSET 1.50k 55 0 5 10 15 20 C1: TAIYO YUDEN JMK212BJ475 (408) 573-4150 LED CURRENT (mA) 1932 TA10a C2: TAIYO YUDEN EMK212BJ105 (408) 573-4150 1932 TA10b D1: ZETEX ZHCS400 (631) 543-7100 L1: PANASONIC ELJEA6R8 (714) 373-7334 Li-Ion Driver for Five White LEDs Efficiency L1 85 4.7µH D1 VIN 2.7V TO 4.2V 80 VIN = 4.2V 6 1 C4.17µF VIN SW Y (%) 75 VIN = 2.7V LT1932 NC 70 PWM 5 3 C2 CIE CDOIMNMTRINOGL SRHSDETN GNLEDD 1µF EFFI 65 4 2 60 RSET 1.50k 15mA 55 0 5 10 15 20 LED CURRENT (mA) C1: TAIYO YUDEN JMK212BJ475 (408) 573-4150 1932 TA11a C2: TAIYO YUDEN TMK316BJ105 (408) 573-4150 1932 TA11b D1: ZETEX ZHCS400 (631) 543-7100 L1: MURATA LQH3C4R7M24 (814) 237-1431 1932f 14

LT1932 TYPICAL APPLICATIOU S Li-Ion Driver for Eight White LEDs Efficiency L1 85 4.7µH D1 VIN 3V TO 4.2V 80 VIN = 4.2V 6 1 VIN SW Y (%) 75 LT1932 NC 70 E C4.17µF 5 SHDN LED 3 C1µ2F FFICI VIN = 3V RSET GND E 65 4 2 3.3V DC 80.6k 60 DIMMING CONTROL RSET 1.50k 15mA 55 0 5 10 15 20 C1: TAIYO YUDEN JMK212BJ475 (408) 573-4150 LED CURRENT (mA) 1932 TA13a C2: TAIYO YUDEN GMK316BJ105 (408) 573-4150 1932 TA13b D1: ZETEX ZHCS400 (631) 543-7100 L1: MURATA LQH3C4R7M24 (814) 237-1431 PACKAGE DESCRIPTIOU S6 Package 6-Lead Plastic SOT-23 (LTC DWG # 05-08-1634) (LTC DWG # 05-08-1636) 2.80 – 3.10 (.110 – .118) (NOTE 3) .20 (.008) A A2 DATUM ‘A’ 2.60 – 3.00 1.50 – 1.75 (.102 – .118) (.059 – .069) (NOTE 3) L 1.90 PIN ONE ID .09 – .20 (.074) A1 (.004 – .008) REF NOTE: (NOTE 2) 1. CONTROLLING DIMENSION: MILLIMETERS SOT-23 SOT-23 MILLIMETERS (Original) (ThinSOT) 2. DIMENSIONS ARE IN (INCHES) .90 – 1.45 1.00 MAX 3. DRAWING NOT TO SCALE A (.035 – .057) (.039 MAX) .95 4. DIMENSIONS ARE INCLUSIVE OF PLATING .00 – 0.15 .01 – .10 (.037) 5. DIMENSIONS ARE EXCLUSIVE OF MOLD FLASH AND METAL BURR A1 (.00 – .006) (.0004 – .004) REF .25 – .50 6. MOLD FLASH SHALL NOT EXCEED .254mm (.010 – .020) 7. PACKAGE EIAJ REFERENCE IS: A2 .90 – 1.30 .80 – .90 (6PLCS, NOTE 2) S6 SOT-23 0401 SC-74A (EIAJ) FOR ORIGINAL (.035 – .051) (.031 – .035) JEDEL MO-193 FOR THIN .35 – .55 .30 – .50 REF L (.014 – .021) (.012 – .019 REF) 1932f Information furnished by Linear Technology Corporation is believed to be accurate and reliable. 15 However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen- tation that the interconnection of its circuits as described herein will not infringe on existing patent rights.

LT1932 TYPICAL APPLICATIOU Li-Ion Driver for Ten White LEDs Efficiency L1 80 VIN 10µH D1 VIN = 4.2V 2.7V TO 4.2V 75 6 1 VIN = 2.7V %) 70 VIN SW Y ( C LT1932 N 65 C1 5 3 C2 CIE 4.7µF SHDN LED 4.7µF FFI RSET GND E 60 4 2 100Ω 100Ω 55 RSET 750Ω 30mA 50 0 5 10 15 20 25 30 C1: TAIYO YUDEN JMK212BJ475 (408) 573-4150 1932 TA16a TOTAL LED CURRENT (mA) C2: TAIYO YUDEN TMK325BJ475 (408) 573-4150 D1: ZETEX ZHCS400 (631) 543-7100 1932 TA16b L1: MURATA LQH3C100M24 (814) 237-1431 Li-Ion Driver for Six White LEDs Efficiency L1 85 4.7µH D1 VIN 2.7V TO 4.2V 80 VIN = 4.2V 6 1 VIN SW Y (%) 75 VIN = 2.7V LT1932 NC 70 E C4.17µF 5 SHDN LED 3 C1µ2F FFICI RSET GND E 65 4 2 3.3V DC 80.6k 60 DIMMING CONTROL RSET 1.50k 15mA 55 0 5 10 15 20 LED CURRENT (mA) C1: TAIYO YUDEN JMK212BJ475 (408) 573-4150 1932 TA12a C2: TAIYO YUDEN TMK316BJ105 (408) 573-4150 1932 TA12b D1: ZETEX ZHCS400 (631) 543-7100 L1: MURATA LQH3C4R7M24 (814) 237-1431 RELATED PARTS PART NUMBER DESCRIPTION COMMENTS LT1615 Micropower DC/DC Converter in 5-Lead ThinSOT 20V at 12mA from 2.5V Input, ThinSOT Package LT1617 Micropower Inverting DC/DC Converter in 5-Lead ThinSOT –15V at 12mA from 2.5V Input, ThinSOT Package LT1618 Constant-Current/Constant-Voltage DC/DC Converter Drives 20 White LEDs from Li-Ion, MS10 Package LTC1682 Doubler Charge Pump with Low Noise Linear Regulator 3.3V and 5V Outputs with 60m V Noise, Up to 80mA Output RMS LT1930 1.4MHz Switching Regulator in 5-Lead ThinSOT 5V at 480mA from 3.3V Input, ThinSOT Package LT1931 Inverting 1.2MHz Switching Regulator in 5-Lead ThinSOT –5V at 350mA from 5V Input, ThinSOT Package LTC3200 Low Noise Regulated Charge Pump 5V Output with Up to 100mA Output LTC3201 Ultralow Noise, Charge Pump 100mA, Integrated LP Filter, MSOP8 LTC3202 High Efficiency, Fractional Charge Pump 125mA, Integrated 2-Bit DAC 1932f 16 Linear Technology Corporation LT/TP 1201 2K • PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 l FAX: (408) 434-0507 l www.linear.com ª LINEAR TECHNOLOGY CORPORATION 2001