LTC1144 Switched-Capacitor Wide Input Range Voltage Converter with Shutdown Features Description Wide Operating Supply Voltage Range: 2V to 18V Boost Pin (Pin 1) for Higher Switching Frequency Simple Conversion of 15V to –15V Supply Low Output Resistance: 120Ω Maximum Power Shutdown to 8µA with SHDN Pin Open Circuit Voltage Conversion Efficiency: 99.9% Typical n Power Conversion Efficiency: 93% Typical n Easy to Use The LTC®1144 is a monolithic CMOS switched-capacitor voltage converter. It performs supply voltage conversion from positive to negative from an input range of 2V to 18V, resulting in complementary output voltages of –2V to –18V. Only two noncritical external capacitors are needed for the charge pump and charge reservoir functions. n n n n n n Applications n n n n n n n Conversion of 15V to ±15V Supplies Inexpensive Negative Supplies Data Acquisition Systems High Voltage Upgrade to LTC1044 or 7660 Voltage Division and Multiplications Automotive Applications Battery Systems with Wall Adapter/Charger The converter has an internal oscillator that can be overdriven by an external clock or slowed down when connected to a capacitor. The oscillator runs at a 10kHz frequency when unloaded. A higher frequency outside the audio band can also be obtained if the Boost Pin is tied to V+. The SHDN pin reduces supply current to 8µA and can be used to save power when the converter is not in use. The LTC1144 contains an internal oscillator, divide-by- two, voltage level shifter, and four power MOSFETs. A special logic circuit will prevent the power N-channel switch substrate from turning on. L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. Typical Application Output Voltage vs Load Current, V+ = 15V Generating –15V from 15V LTC1144 2 3 4 CAP+ –15 V+ OSC GND SHDN CAP– VOUT 8 ROUT = 56Ω TA = 25°C 15V INPUT 7 –14 6 5 –15V OUTPUT 10µF 1144 TA01 OUTPUT VOLTAGE (V) 10µF + BOOST + 1 –13 –12 –11 –10 0 10 30 40 20 LOAD CURRENT (mA) 50 1144 TA02 1144fa For more information www.linear.com/LTC1144 1 LTC1144 Absolute Maximum Ratings (Note 1) Supply Voltage (V+) (Transient) ................................20V Supply Voltage (V+) (Operating) ............................... 18V Input Voltage on Pins 1, 6, 7 (Note 2) ............................. –0.3V < VIN < (V+) + 0.3V Output Short-Circuit Duration V+ ≤ 10V ..................................................... Indefinite V+ ≤ 15V .......................................................... 30 sec V+ ≤ 20V .............................................. Not Protected Power Dissipation.............................................. 500mW Operating Temperature Range LTC1144C................................................. 0°C to 70°C LTC1144I...............................................–40°C to 85°C Storage Temperature Range................... –65°C to 150°C Lead Temperature (Soldering, 10 sec).................... 300°C Pin Configuration TOP VIEW TOP VIEW BOOST 1 + 8 V+ BOOST 1 8 V+ CAP+ 2 7 OSC 2 7 OSC GND 3 6 SHDN GND 3 6 SHDN CAP– 4 5 VOUT CAP– 4 5 VOUT CAP N8 PACKAGE 8-LEAD PLASTIC DIP TJMAX = 110°C, θJA = 100°C/W S8 PACKAGE 8-LEAD PLASTIC SOIC TJMAX = 110°C, θJA = 130°C/W Order Information LEAD FREE FINISH TAPE AND REEL PART MARKING PACKAGE DESCRIPTION TEMPERATURE RANGE LTC1144CN8#PBF LTC1144CN8#TRPBF LTC1144CN8 8-Lead Plastic DIP 0°C to 70°C LTC1144IN8#PBF LTC1144IN8#TRPBF LTC1144IN8 8-Lead Plastic DIP –40°C to 85°C LTC1144CS8#PBF LTC1144CS8#TRPBF 1144 8-Lead Plastic SOIC 0°C to 70°C LTC1144IS8#PBF LTC1144IS8#TRPBF 1144I 8-Lead Plastic SOIC –40°C to 85°C Consult LTC Marketing for parts specified with wider operating temperature ranges. Consult LTC Marketing for information on nonstandard lead based finish parts. For more information on lead free part marking, go to: http://www.linear.com/leadfree/ For more information on tape and reel specifications, go to: http://www.linear.com/tapeandreel/ 1144fa 2 For more information www.linear.com/LTC1144 LTC1144 Electrical Characteristics The l denotes the specifications which apply over the full operating temperature range,V+ = 15V, COSC = 0pF, Test Circuit Figure 1, otherwise specifications are at TA = 25°C. LTC1144C SYMBOL IS PARAMETER CONDITIONS Supply Voltage Range RL = 10k Supply Current RL = ∞, Pins 1, 6 No Connection, l fOSC = 10kHz l SHDN = 0V, RL = ∞, Pins 1, 7 No Connection V+ = 5V, RL = ∞, Pins 1, 6 No Connection, fOSC = 4kHz V+ = 5V, SHDN = 0V, RL = ∞, Pins 1, 7 No Connection ROUT Output Resistance MIN TYP 2 0.008 l l 2 0.03 0.008 MAX UNITS 18 V 1.1 1.6 mA mA 0.035 mA 0.10 0.15 mA mA 0.002 0.015 0.002 0.018 mA 56 100 120 56 100 140 Ω Ω 90 250 90 300 Ω l Oscillator Frequency V+ = 15V (Note 3) V+ = 5V Power Efficiency RL = 2k at 10kHz l 90 93 Voltage Conversion Efficiency RL = ∞ l 97.0 99.9 Oscillator Sink or Source Current V+ = 5V (VOSC = 0V to 5V) V+ = 15V (VOSC = 0V to 15V) 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: Connecting any input terminal to voltages greater than V+ or less than ground may cause destructive latch-up. It is recommended that no inputs from sources operating from external supplies be applied prior to power-up of the LTC1144. 18 TYP 0.10 0.13 l l fOSC MIN 1.1 1.3 V+ = 15V, IL = 20mA at 10kHz V+ = 5V, IL = 3mA at 4kHz LTC1144I MAX 10 4 0.5 4 10 4 kHz kHz 90 93 % 97.0 99.9 % 0.5 4 µA µA Note 3: fOSC is tested with COSC = 100pF to minimize the effects of test fixture capacitance loading. The 0pF frequency is correlated to this 100pF test point, and is intended to simulate the capacitance at pin 7 when the device is plugged into a test socket and no external capacitor is used. 1144fa For more information www.linear.com/LTC1144 3 LTC1144 Typical Performance Characteristics Output Resistance vs Supply Voltage 300 Output Resistance vs Temperature 200 150 100 V + = 5V IL = 3mA 100 80 60 V + = 15V IL = 20mA 40 50 6 10 12 14 8 SUPPLY VOLTAGE (V) 16 20 –55 –25 18 50 25 75 0 TEMPERATURE (°C) Oscillator Frequency as a Function of COSC OSCILLATOR FREQUENCY (kHz) OSCILLATOR FREQUENCY (kHz) 1000 100 BOOST = V + 10 1 BOOST = OPEN OR GROUND 0.1 BOOST = OPEN OR GROUND 1 –55 –25 0 25 50 75 TEMPERATURE (°C) 5 10 15 20 LOAD CURRENT (mA) OUTPUT VOLTAGE (V) SUPPLY CURRENT (µA) 25 30 LTC1144 • TPC07 16 18 TA = 25°C V+ = 15V C1 = C2 = 10µF BOOST = OPEN –5 –10 –15 125 0 10 20 30 40 LOAD CURRENT (mA) LTC1144 • TPC06 100 100 1000 V + = 15V 100 V + = 5V 10 1 10 0.1 OSCILLATOR FREQUENCY (kHz) 60 Power Conversion Efficiency and Supply Current vs Load Current TA = 25°C C1 = C2 = 10µF 1 0.01 50 100 LTC1144 • TPC08 PEFF 80 80 IS 60 60 40 40 20 0 0 TA = 25°C V+ = 15V 20 C1 = C2 = 10µF BOOST = OPEN (SEE TEST CIRCUIT) 0 10 30 40 50 20 LOAD CURRENT (mA) SUPPLY CURRENT (mA) 0 8 10 12 14 SUPPLY VOLTAGE (V) LTC1144 • TPC05 10000 ROUT = 90Ω –5 100 Supply Current as a Function of Oscillator Frequency –4 6 ROUT = 56Ω Output Voltage vs Load Current –3 4 Output Voltage vs Load Current BOOST = V + LTC1144 • TPC04 –2 2 LTC1144 • TPC03 TA = 25°C V + = 15V 10 100 10 1000 1 10000 EXTERNAL CAPACITANCE (PIN 7 TO GND), COSC (pF) –1 1 0 100 0.01 TA = 25°C V+ = 5V C1 = C2 = 10µF BOOST = OPEN BOOST = OPEN OR GROUND 10 Oscillator Frequency vs Temperature TA = 25°C V + = 15V 0 BOOST = V + LTC1144 • TPC02 LTC1144 • TPC01 1000 TA = 25°C COSC = 0 100 125 100 OUTPUT VOLTAGE (V) 4 POWER CONVERSION EFFICIENCY (%) 2 OSCILLATOR FREQUENCY (kHz) 120 OUTPUT RESISTANCE (Ω) OUTPUT RESISTANCE (Ω) 1000 140 TA = 25°C 250 0 Oscillator Frequency vs Supply Voltage LTC1144 • TPC09 1144fa 4 For more information www.linear.com/LTC1144 LTC1144 Typical Performance Characteristics Power Conversion Efficiency vs Oscillator Frequency 30 60 IS 20 4 20 TA = 25°C V + = 5V C1 = C2 = 10µF BOOST = OPEN (SEE TEST CIRCUIT) 12 16 8 LOAD CURRENT (mA) 20 10 95 100µF 10µF 90 85 IL = 3mA 1µF 80 75 0.1 –1 1µF 0.1µF 0.1µF 10µF 500 1µF 1µF 100µF IL = 20mA 1 10 OSCILLATOR FREQUENCY (kHz) 0 0.1 100 1 10 OSCILLATOR FREQUENCY (kHz) Output Voltage vs Load Current 0 V + = 5V TA = 25°C C1 = C2 BOOST = 5V BOOST = OPEN –2 0.1µF 10µF 0.1µF –3 1µF 1µF 10µF –5 V + = 15V TA = 25°C C1 = C2 BOOST = 15V BOOST = OPEN 0.1µF –10 0.1µF –4 10µF 0 0.01 0.1 1 10 LOAD CURRENT (mA) 100 –5 0.001 0.01 0.1 1 10 LOAD CURRENT (mA) 100 –15 0.001 LTC1144 • G14 LTC1144 • TPC13 100 LTC1144 • TPC12 Output Voltage vs Load Current 0 V + = 5V OUTPUT VOLTAGE (V) RIPPLE VOLTAGE (mV) 1000 10µF LTC1144 • TPC11 Ripple Voltage vs Load Current TA = 25°C C1 = C2 BOOST = 5V BOOST = OPEN TA = 25°C V + = 15V 1000 1µF LTC1144 • TPC10 1500 3000 2000 10µF 70 0 TA = 25°C, V + = 15V BOOST = OPEN 100µF OUTPUT VOLTAGE (V) 40 0 POWER CONVERSION EFFICIENCY (%) 40 SUPPLY CURRENT (mA) POWER CONVERSION EFFICIENCY (%) PEFF 80 0 100 50 100 Output Resistance vs Oscillator Frequency OUTPUT RESISTANCE (Ω) Power Conversion Efficiency and Supply Current vs Load Current 1µF 1µF 10µF 10µF 0.01 10 0.1 1 LOAD CURRENT (mA) 100 LTC1144 • TPC15 Pin Functions Boost (Pin 1): This pin will raise the oscillator frequency by a factor of 10 if tied high. CAP+ (Pin 2): Positive Terminal for Pump Capacitor. SHDN (Pin 6): Shutdown Pin. Tie to V+ pin or leave floating for normal operation. Tie to ground when in shutdown mode. CAP– (Pin 4): Negative Terminal for Pump Capacitor. OSC (Pin 7): Oscillator Input Pin. This pin can be overdriven with an external clock or can be slowed down by connecting an external capacitor between this pin and ground. VOUT (Pin 5): Output of the Converter. V+ (Pin 8): Input Voltage. GND (Pin 3): Ground Reference. 1144fa For more information www.linear.com/LTC1144 5 LTC1144 Test Circuit V+ 15V 1 2 C1 + 3 10µF IS 8 EXTERNAL OSCILLATOR R L 7 LTC1144 4 6 IL 5 COSC C2 10µF VOUT + 1144 F01 Figure 1. Applications Information Theory of Operation To understand the theory of operation of the LTC1144, a review of a basic switched-capacitor building block is helpful. In Figure 2, when the switch is in the left position, capacitor C1 will charge to voltage V1. The total charge on C1 will be q1 = C1V1. The switch then moves to the right, discharging C1 to voltage V2. After this discharge time, the charge on C1 is q2 = C1V2. Note that charge has been transferred from the source V1 to the output V2. The amount of charge transferred is: REQUIV = 1/(f × C1). Thus, the equivalent circuit for the switched-capacitor network is as shown in Figure 3. Examination of Figure 4 shows that the LTC1144 has the same switching action as the basic switched-capacitor building block. With the addition of finite switch onresistance and output voltage ripple, the simple theory, although not exact, provides an intuitive feel for how the device works. For example, if you examine power conversion efficiency as a function of frequency (see Figure 5), this simple ∆q = q1 – q2 = C1(V1 – V2) V1 V1 REQUIV C2 V2 1 REQUIV = f × C1 f RL C1 V2 C2 RL 1144 F03 Figure 3. Switched-Capacitor Equivalent Circuit 1144 F02 Figure 2. Switched-Capacitor Building Block If the switch is cycled f times per second, the charge transfer per unit time (i.e., current) is: Rewriting in terms of voltage and impedance equivalence, BOOST V1− V2 V1− V2 = 1 REQUIV f ×C1 SW1 φ 10X (1) I = f × ∆q = f × C1(V1 – V2) I= V+ (8) ÷2 OSC OSC (7) φ CAP + (2) C1 SW2 + CAP – (4) VOUT (5) + GND (3) SHDN (6) A new variable REQUIV has been defined such that C2 1144 F04 Figure 4. LTC1144 Switched-Capacitor Voltage Converter Block Diagram 1144fa 6 For more information www.linear.com/LTC1144 LTC1144 Applications Information theory will explain how the LTC1144 behaves. The loss, and hence the efficiency, is set by the output impedance. As frequency is decreased, the output impedance will eventually be dominated by the 1/(f × C1) term and power efficiency will drop. V+ 9I BOOST (1) Note also that power efficiency decreases as frequency goes up. This is caused by internal switching losses which occur due to some finite charge being lost on each switching cycle. This charge loss per unit cycle, when multiplied by the switching frequency, becomes a current loss. At high frequency this loss becomes significant and the power efficiency starts to decrease. 90 400 85 300 80 200 OUTPUT RESISTANCE 75 70 0.1 GND (3) 500 POWER CONVERSION EFFICIENCY 1144 F06 V+ REQUIRED FOR TTL LOGIC NC C1 + 1 8 2 7 3 LTC1144 4 6 5 100 1 10 OSCILLATOR FREQUENCY (kHz) ≈20pF I Figure 6. Oscillator OUTPUT RESISTANCE (Ω) POWER CONVERSION EFFICIENCY (%) 95 9I 600 V + = 15V, C1 = C2 = 10µF IL = 20mA, TA = 25°C SCHMITT TRIGGER OSC (7) 100k OSC INPUT –(V + 100 I 0 100 +) C2 1144 F07 Figure 7. External Clocking 1144 F05 Figure 5. Power Conversion Efficiency and Output Resistance vs Oscillator Frequency SHDN (Pin 6) The LTC1144 has a SHDN pin that will disable the internal oscillator when it is pulled low. The supply current will also drop to 8µA. OSC (Pin 7) and Boost (Pin 1) The switching frequency can be raised, lowered or driven from an external source. Figure 6 shows a functional diagram of the oscillator circuit. By connecting the boost pin (pin 1) to V+, the charge and discharge current is increased, and hence the frequency is increased by approximately 10 times. Increasing the frequency will decrease output impedance and ripple for higher load currents. Loading pin 7 with more capacitance will lower the frequency. Using the boost (pin 1) in conjunction with external capacitance on pin 7 allows user selection of the frequency over a wide range. Driving the LTC1144 from an external frequency source can be easily achieved by driving pin 7 and leaving the boost pin open as shown in Figure 7. The output current from pin 7 is small, typically 4µA, so a logic gate is capable of driving this current. The choice of using a CMOS logic gate is best because it can operate over a wide supply voltage range (3V to 15V) and has enough voltage swing to drive the internal Schmitt trigger shown in Figure 6. For 5V applications, a TTL logic gate can be used by simply adding an external pull-up resistor (see Figure 7). Capacitor Selection External capacitors C1 and C2 are not critical. Matching is not required, nor do they have to be high quality or tight tolerance. Aluminum or tantalum electrolytics are excellent choices, with cost and size being the only consideration. 1144fa For more information www.linear.com/LTC1144 7 LTC1144 Typical Applications Negative Voltage Converter V IN 2V TO 18V Figure 8 shows a typical connection which will provide a negative supply from an available positive supply. This circuit operates over full temperature and power supply ranges without the need of any external diodes. The output voltage (pin 5) characteristics of the circuit are those of a nearly ideal voltage source in series with a 56Ω resistor. The 56Ω output impedance is composed of two terms: 1) the equivalent switched capacitor resistance (see Theory of Operation), and 2) a term related to the on-resistance of the MOS switches. V+ 2V TO 18V 1 3 2 7 3 4 Vd 1N4148 + 5 4 + 10µF VOUT = 2(VIN – 1) + 10µF 1144 F09 Figure 9. Voltage Doubler Ultra-Precision Voltage Divider An ultra-precision voltage divider is shown in Figure 10. To achieve the 0.002% accuracy indicated, the load current should be kept below 100nA. However, with a slight loss in accuracy, the load current can be increased. 6 1 VOUT = –V + 10µF C1 10µF 1144 F08 At an oscillator frequency of 10kHz and C1 = 10µF, the first term is: 1 1 = = 20Ω 3 (fOSC / 2) ×C1 5×10 ×10 ×10−6 Notice that the above equation for REQUIV is not a capacitive reactance equation (XC = 1/ωC) and does not contain a 2π term. The exact expression for output impedance is extremely complex, but the dominant effect of the capacitor is clearly shown in Figure 5. For C1 = C2 = 10µF, the output impedance goes from 56Ω at fOSC = 10kHz to 250Ω at fOSC = 1kHz. As the 1/(f × C) term becomes large compared to the switch on-resistance term, the output resistance is determined by 1/(f × C) only. 8 2 + 3 7 LTC1144 6 4 V+ ±0.002% 2 TMIN ≤ TA ≤ TMAX IL ≤ 100nA Figure 8. Negative Voltage Converter 6 V+ 4V TO 36V 5 TMIN ≤ TA ≤ TMAX REQUIV = LTC1144 Vd + 1N4148 7 LTC1144 + 10µF 8 8 2 + 1 + 5 C2 10µF 1144 F10 Figure 10. Ultra-Precision Voltage Divider Battery Splitter A common need in many systems is to obtain (+) and (–) supplies from a single battery or single power supply system. Where current requirements are small, the circuit shown in Figure 11 is a simple solution. It provides symmetrical ± output voltages, both equal to one half the input voltage. The output voltages are both referenced to pin 3 (output common). VB 18V + C1 10µF + 1 8 2 7 3 4 LTC1144 VB /2 9V 6 5 –VB /2 –9V Voltage Doubling + Figure 9 shows a two-diode capacitive voltage doubler. With a 15V input, the output is 29.45V with no load and 28.18V with a 10mA load. C2 10µF OUTPUT COMMON 1144 F11 Figure 11. Battery Splitter 1144fa 8 For more information www.linear.com/LTC1144 LTC1144 Package Description Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings. N Package 8-Lead PDIP (Narrow .300 Inch) (Reference LTC DWG # 05-08-1510 Rev I) .400* (10.160) MAX 8 7 6 5 1 2 3 4 .255 ±.015* (6.477 ±0.381) .300 – .325 (7.620 – 8.255) .008 – .015 (0.203 – 0.381) ( +.035 .325 –.015 8.255 +0.889 –0.381 ) .045 – .065 (1.143 – 1.651) .065 (1.651) TYP .100 (2.54) BSC .130 ±.005 (3.302 ±0.127) .120 (3.048) .020 MIN (0.508) MIN .018 ±.003 N8 REV I 0711 (0.457 ±0.076) NOTE: 1. DIMENSIONS ARE INCHES MILLIMETERS *THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS. MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED .010 INCH (0.254mm) 1144fa For more information www.linear.com/LTC1144 9 LTC1144 Package Description Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings. S8 Package 8-Lead Plastic Small Outline (Narrow .150 Inch) (Reference LTC DWG # 05-08-1610 Rev G) .189 – .197 (4.801 – 5.004) NOTE 3 .045 ±.005 .050 BSC 8 .245 MIN .160 ±.005 .010 – .020 × 45° (0.254 – 0.508) 2 .053 – .069 (1.346 – 1.752) 0°– 8° TYP .016 – .050 (0.406 – 1.270) 5 .150 – .157 (3.810 – 3.988) NOTE 3 1 RECOMMENDED SOLDER PAD LAYOUT .008 – .010 (0.203 – 0.254) 6 .228 – .244 (5.791 – 6.197) .030 ±.005 TYP NOTE: 1. DIMENSIONS IN 7 .014 – .019 (0.355 – 0.483) TYP INCHES (MILLIMETERS) 2. DRAWING NOT TO SCALE 3. THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS. MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED .006" (0.15mm) 4. PIN 1 CAN BE BEVEL EDGE OR A DIMPLE 3 4 .004 – .010 (0.101 – 0.254) .050 (1.270) BSC SO8 REV G 0212 1144fa 10 For more information www.linear.com/LTC1144 LTC1144 Revision History REV DATE DESCRIPTION A 04/14 Change 0.0002% to 0.002% under the Ultra-Precision Voltage Divider section. PAGE NUMBER 8 1144fa 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. For more information www.linear.com/LTC1144 11 LTC1144 Typical Application Regulated –5V Output Voltage 9V 1 Figure 12 shows a regulated –5V output with a 9V input. With a 0mA to 5mA load current, the ROUT is below 20Ω. 1µF 8 2 + 3 7 LTC1144 6 4 Paralleling for Lower Output Resistance Additional flexibility of the LTC1144 is shown in Figure 13. Two LTC1144s are connected in parallel to provide a lower effective output resistance. However, if the output resistance is dominated by 1/(f × C1), increasing the capacitor size (C1) or increasing the frequency will be of more benefit than the paralleling circuit shown. 2N2369 5 36k 300k – 5V 100µF + 1144 F12 Figure 12. A Regulated –5V Supply V+ 8 1 C1 10µF + 7 2 3 LTC1144 6 5 4 8 1 C1 10µF + 7 2 3 LTC1144 6 5 4 VOUT = –(V +) + 1/4 CD4077* C2 20µF * THE EXCLUSIVE NOR GATE SYNCHRONIZES BOTH LTC1144s TO MINIMIZE RIPPLE 1144 F13 Figure 13. Paralleling for Lower Output Resistance Related Parts PART NUMBER DESCRIPTION COMMENTS LTC1054 15V, 100mA Inverting Charge Pump VIN = 3.5V to 15V, VOUT(MAX) = ±15V, IQ = 2.5mA, ISD = <1µA, DIP-8, S0-8 Packages LTC1046 6V, 100mA Inverting Charge Pump VIN = 1.5V to 6V, VOUT(MAX) = 3V, IQ = 200µA, ISD = <1µA, SO-8 Package LT®3463/ LT3463A 250mA (ISW), Boost/Inverter Dual, Micropower DC/DC Converter with Integrated Schottky Diodes VIN = 2.4V to 15V, VOUT(MAX) = ±40V, IQ = 40µA, ISD = <1µA, DFN Package LT1615/ LT1615-1 300mA/80mA ISW, Constant Off-Time, High Efficiency VIN = 1.2V to 15V, VOUT(MAX) = 34V, IQ = 20µA, ISD = <1µA, ThinSOT Package Step-Up DC/DC Converter LT3467/ LT3467A 1.1A (ISW), 1.3MHz/2.1MHz, High Efficiency Step-Up DC/DC Converter with Integrated Soft-Start VIN = 2.4V to 16V, VOUT(MAX) = 40V, IQ = 1.2mA, ISD = <1µA, ThinSOT Package LT1931/ LT1931A 1A (ISW), 1.2MHz/2.2MHz High Efficiency Inverting DC/DC Converter VIN = 2.6V to 16V, VOUT(MAX) = 34V, IQ = 4.2mA/5.5mA, ISD = <1µA, ThinSOT Package 1144fa 12 Linear Technology Corporation 1630 McCarthy Blvd., Milpitas, CA 95035-7417 For more information www.linear.com/LTC1144 (408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com/LTC1144 LT 0414 REV A • PRINTED IN USA LINEAR TECHNOLOGY CORPORATION 1994