LTC660 100mA CMOS Voltage Converter U DESCRIPTION FEATURES ■ ■ ■ ■ ■ ■ ■ ■ Simple Conversion of 5V to – 5V Supply Output Drive: 100mA ROUT: 6.5Ω (0.65V Loss at 100mA) BOOST Pin (Pin 1) for Higher Switching Frequency Inverting and Doubling Modes Minimum Open Circuit Voltage Conversion Efficiency: 99% Typical Power Conversion Efficiency with a 100mA Load: 88% Easy to Use U APPLICATIONS ■ ■ ■ ■ Conversion of 5V to ±5V Supplies Inexpensive Negative Supplies Data Acquisition Systems High Current Upgrade to LTC1044 or LTC7660 The LTC®660 is a monolithic CMOS switched-capacitor voltage converter. It performs supply voltage conversion from positive to negative from an input range of 1.5V to 5.5V, resulting in complementary output voltages of – 1.5V to – 5.5V. It also performs a doubling at an input voltage range of 2.5V to 5.5V, resulting in a doubled output voltage of 5V to 11V. Only two external capacitors are needed for the charge pump and charge reservoir functions. 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 LTC660 contains an internal oscillator, divide-by-two, voltage level shifter and four power MOSFETs. , LTC and LT are registered trademarks of Linear Technology Corporation. U TYPICAL APPLICATION Output Voltage vs Load Current for V + = 5V Generating – 5V from 5V + C1 150µF 3 4 CAP + OSC LTC660 GND CAP – LV VOUT –5.0 8 5V INPUT TA = 25°C ROUT = 6.5Ω 7 –4.8 6 5 –5V OUTPUT C2 150µF 660 TA01 OUTPUT VOLTAGE (V) 2 V+ BOOST + 1 –4.6 –4.4 –4.2 –4.0 0 20 60 80 40 LOAD CURRENT (mA) 100 660 TA02 1 LTC660 W U U W W U W ABSOLUTE MAXIMUM RATINGS PACKAGE/ORDER INFORMATION (Note 1) ORDER PART NUMBER TOP VIEW Supply Voltage (V +) .................................................. 6V Input Voltage on Pins 1, 6, 7 (Note 2) ............................ – 0.3V < VIN < (V + + 0.3V) Output Short-Circuit Duration to GND (Note 5) ............................................................. 1 sec Power Dissipation.............................................. 500mW Operating Temperature Range .................... 0°C to 70°C Storage Temperature Range ................. – 65°C to 150°C Lead Temperature (Soldering, 10 sec).................. 300°C BOOST 1 CAP + 2 GND 3 CAP – 4 8 V+ 7 OSC LTC660CN8 LTC660CS8 6 LV 5 VOUT N8 PACKAGE 8-LEAD PLASTIC DIP S8 PART MARKING S8 PACKAGE 8-LEAD PLASTIC SOIC 660 TJMAX = 100°C, θJA = 100°C/W (N) TJMAX = 100°C, θJA = 150°C/W (S) Consult Factory for Industrial and Military grade parts. ELECTRICAL CHARACTERISTICS V + = 5V, C1 and C2 = 150µF, Boost = Open, COSC = 0pF, TA = 25°C, unless otherwise noted. SYMBOL PARAMETER CONDITIONS MIN Supply Voltage RL = 1k Inverter, LV = Open Inverter, LV = GND Doubler, LV = VOUT ● ● ● IS Supply Current No Load Boost = Open Boost = V + ● ● IOUT Output Current VOUT More Negative Than – 4V ● ROUT Output Resistance IL = 100mA (Note 3) ● fOSC Oscillator Frequency Boost = Open Boost = V + (Note 4) Power Efficiency RL = 1k Connected Between V + and VOUT RL = 500Ω Connected Between VOUT and GND IL = 100mA to GND Voltage Conversion Efficiency No Load Oscillator Sink or Source Current Boost = Open Boost = V + The ● denotes specifications which apply over the full operating temperature range; all other limits and typicals are at TA = 25°C. Note 1: Absolute Maximum Ratings are those values beyond which the life of a device may be impaired. 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 source operating from external supplies be applied prior to power-up of the LTC660. Note 3: The output resistance is a combination of internal switch resistance and external capacitor ESR. To maximize output voltage and efficiency, keep external capacitor ESR < 0.2Ω. 2 ● ● TYP 3 1.5 2.5 MAX UNITS 5.5 5.5 5.5 V V V 0.08 0.23 0.5 3 mA mA 6.5 10 100 mA Ω 10 80 kHz kHz 96 92 98 96 88 % % % 99 99.96 % ±1.1 ±5.0 µA µA Note 4: 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. Note 5: OUT may be shorted to GND for 1 sec without damage, but shorting OUT to V + may damage the device and should be avoided. Also, for temperatures above 85°C, OUT must not be shorted to GND or V +, even instantaneously, or device damage may result. LTC660 U W TYPICAL PERFORMANCE CHARACTERISTICS (Using Test Circuit in Figure 1) 100 1000 300 TA = 25°C V + = 5V SUPPLY CURRENT (µA) 250 200 150 BOOST = V + 100 BOOST = OPEN TA = 25°C V + = 5V BOOST = OPEN 90 OUTPUT RESISTANCE (Ω) TA = 25°C SUPPLY CURRENT (µA) Output Resistance vs Oscillator Frequency Supply Current vs Oscillator Frequency Supply Current vs Supply Voltage 100 10 50 80 70 60 C1 = C2 = 150µF C1 = C2 = 1500µF 50 40 C1 = C2 = 22µF 30 20 10 0 1.5 2 4 4.5 2.5 3 3.5 SUPPLY VOLTAGE (V) 5 1 0.01 5.5 0.1 100 1 10 OSCILLATOR FREQUENCY (kHz) Output Resistance vs Supply Voltage –3.0 100 BOOST = OPEN 10 8 6 4 LTC660 EFFICIENCY –3.4 20 V + = 1.5V 15 V + = 3V 10 V + = 5V OUTPUT VOLTAGE (V) OUTPUT RESISTANCE (Ω) 12 TA = 25°C BOOST = OPEN 88 –3.8 84 –4.2 76 80 LTC660 OUTPUT VOLTAGE –4.6 5 72 68 2 64 0 –60 –40 –20 0 20 40 60 80 100 120 140 TEMPERATURE (°C) 0 1 3 4 2 SUPPLY VOLTAGE (V) 5 6 100 TA = 25°C BOOST = OPEN V + = 5.5V Output Voltage Drop vs Load Current V + = 5.5V V + = 4.5V V + = 3.5V 75 70 V + = 1.5V V + = 2.5V EFFICIENCY (%) 90 80 85 + V = 2.5V 70 60 60 LTC660 • TPC07 V + = 3.5V 75 65 10 20 30 40 50 60 70 80 90 100 LOAD CURRENT (mA) V + = 4.5V 80 65 0 LTC660 • TPC06 1.0 TA = 25°C BOOST = V + 95 90 85 60 10 20 30 40 50 60 70 80 90 100 LOAD CURRENT (mA) Efficiency vs Load Current Efficiency vs Load Current 95 0 LTC660 • TPC05 LTC690 • TPC04 100 –5.0 V + = 1.5V TA = 25°C BOOST = OPEN 0.9 OUTPUT VOLTAGE DROP FROM SUPPLY VOLTAGE (V) 0 EFFICIENCY (%) 96 92 EFFICIENCY (%) OUTPUT RESISTANCE (Ω) Output Voltage and Efficiency vs Load Current, V + = 5V 25 14 100 LTC660 • TPC03 Output Resistance vs Temperature TA = 25°C BOOST = OPEN 16 1 10 OSCILLATOR FREQUENCY (kHz) LTC660 • G02 LTC660 • G01 18 0 0.1 1000 0.8 V + = 2.5V 0.7 + V = 1.5V 0.6 0.5 V + = 3.5V V + = 4.5V 0.4 0.3 V + = 5.5V 0.2 0.1 0 0 10 20 30 40 50 60 70 80 90 100 LOAD CURRENT (mA) LTC660 • TPC08 0 10 20 30 40 50 60 70 80 90 100 LOAD CURRENT (mA) LTC660 • TPC09 3 LTC660 U W TYPICAL PERFORMANCE CHARACTERISTICS (Using Test Circuit in Figure 1) Output Voltage Drop vs Load Current Output Voltage vs Oscillator Frequency 1.0 TA = 25°C BOOST = V + IL = 1mA 0.8 95 90 –4.5 V + = 2.5V 0.6 0.5 V + = 1.5V 0.4 V + = 3.5V V + = 4.5V 0.3 V + = 5.5V 0.2 IL = 10mA –4.0 IL = 80mA –3.5 –3.0 TA =25°C V+ = 5V BOOST = OPEN 0.1 10 20 30 40 50 60 70 80 90 100 LOAD CURRENT (mA) 1 10 OSCILLATOR FREQUENCY (kHz) LTC660 • TPC10 70 55 50 0.1 100 6 4 2 70 60 50 40 30 20 10 8 6 4 2 V+ = 5V BOOST = OPEN OSC = OPEN 0 –60 –40 –20 0 20 40 60 80 100 120 140 TEMPERATURE (°C) 0 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 SUPPLY VOLTAGE (V) 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 SUPPLY VOLTAGE (V) LTC660 • TPC15 LTC660 • TPC14 LTC660 • TPC13 Oscillator Frequency vs External Capacitance Oscillator Frequency vs Temperature 100 100 OSCILLATOR FREQUENCY (kHz) OSCILLATOR FREQUENCY (kHz) 90 80 70 60 50 40 30 20 10 V+ = 5V BOOST = V+ OSC = OPEN 0 –60 –40 –20 0 20 40 60 80 100 120 140 TEMPERATURE (°C) LTC660 • TPC16 4 100 12 TA = 25°C 90 BOOST = V+ OSC = OPEN 80 10 0 1 10 OSCILLATOR FREQUENCY (kHz) Oscillator Frequency vs Temperature OSCILLATOR FREQUENCY (kHz) 8 TA = 25°C V+ = 5V BOOST = OPEN LTC660 • TPC12 100 OSCILLATOR FREQUENCY (kHz) OSCILLATOR FREQUENCY (kHz) 10 IL = 1mA 75 Oscillator Frequency vs Supply Voltage TA = 25°C BOOST = OPEN OSC = OPEN IL = 80mA LTC660 • TPC11 Oscillator Frequency vs Supply Voltage 12 IL = 10mA 80 60 –2.5 0 85 65 0.1 0 EFFICIENCY (%) 0.7 OUTPUT VOLTAGE (V) OUTPUT VOLTAGE DROP FROM SUPPLY VOLTAGE (V) 0.9 Efficiency vs Oscillator Frequency 100 –5.0 BOOST = V + 10 1 BOOST = OPEN 0.1 00.1 1 10 100 1000 CAPACITANCE (pF) 10000 LTC660 • TPC17 LTC660 U U PIN NAME INVERTER DOUBLER 1 BOOST Internal Oscillator Frequency Control Pin. BOOST = Open, fOSC = 10kHz typ; BOOST = V +, fOSC = 80kHz typ; when OSC is driven externally BOOST has no effect. Same 2 CAP + Positive Terminal for Charge Pump Capacitor Same 3 GND Power Supply Ground Input Positive Voltage Input 4 CAP – Negative Terminal for Charge Pump Capacitor Same 5 VOUT Negative Voltage Output Power Supply Ground Input 6 LV Tie LV to GND when the input voltage is less than 3V. LV may be connected to GND or left open for input voltages above 3V. Connect LV to GND when overdriving OSC. LV must be tied to VOUT for all input voltages. 7 OSC An external capacitor can be connected to this pin to slow the oscillator frequency. Keep stray capacitance to a minimum. An external oscillator can be applied to this pin to overdrive the internal oscillator. Same except standard logic levels will not be able to overdrive OSC pin. 8 V+ Positive Voltage Input Positive Voltage Output U PIN FUNCTIONS TEST CIRCUIT + C1 150µF 1 8 2 7 3 4 LTC660 IS V+ 5V EXTERNAL OSCILLATOR 6 COSC 5 RL IL + V+ C1 150µF VOUT LTC660 • F01 Figure 1. Test Circuit 5 LTC660 U U W U APPLICATIONS INFORMATION Theory of Operation V+ (8) I = f • ∆q = f • C1 (V1 – V2) Rewriting in terms of voltage and impedance equivalence, I= V1 − V2 V1 − V2 = 1/ fC1 REQUIV A new variable REQUIV has been defined such that REQUIV = 1/fC1. Thus, the equivalent circuit for the switchedcapacitor network is as shown in Figure 3. Figure 4 shows that the LTC660 has the same switching action as the basic switched-capacitor building block. V2 V1 C1 C2 RL 660 F02 Figure 2. Switched-Capacitor Building Block REQUIV V2 V1 C2 RL SW2 CAP+ (2) BOOST φ 4.5× (1) + C1 OSC +2 φ OSC (7) CAP – (4) VOUT (5) C2 LV (6) ∆q = q1 – q2 = C1 (V1 – V2) If the switch is cycled “f” times per second, the charge transfer per unit time (i.e., current) is: SW1 + To understand the theory of operation for the LTC660, 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 discharging 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: CLOSED WHEN V+ > 3.0V GND (3) LTC660 • F04 Figure 4. LTC660 Switched-Capacitor Voltage Converter Block Diagram This simplified circuit does not include finite on-resistance of the switches and output voltage ripple, however, it does give an intuitive feel for how the device works. For example, if you examine power conversion efficiency as a function of frequency this simple theory will explain how the LTC660 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/fC1 term and voltage losses will rise decreasing the efficiency. As the frequency increases the quiescent current increases. At high frequency this current loss becomes significant and the power efficiency starts to decrease. The LTC660 oscillator frequency is designed to run where the voltage loss is a minimum. With the external 150µF capacitors the effective output impedance is determined by the internal switch resistances and the capacitor ESRs. LV (Pin 6) The internal logic of the LTC660 runs between V + and LV (Pin 6). For V + ≥ 3V, an internal switch shorts LV to ground (Pin 3). For V + < 3V, the LV pin should be tied to ground. For V + ≥ 3V, the LV pin can be tied to ground or left floating. OSC (Pin 7) and BOOST (Pin 1) 1 REQUIV = fC1 660 F03 Figure 3. Switched-Capacitor Equivalent Circuit 6 The switching frequency can be raised, lowered or driven from an external source. Figure 5 shows a functional diagram of the oscillator circuit. LTC660 U U W U APPLICATIONS INFORMATION V+ 7.0I V+ REQUIRED FOR TTL LOGIC NC I + BOOST (1) C1 1 8 2 7 3 LTC660 4 100k OSC INPUT 6 5 –(V +) C2 + OSC (7) SCHMITT TRIGGER Figure 6. External Clocking ∼18pF 7.0I LTC660 • F06 I LV (6) LTC660 • F05 Figure 5. Oscillator By connecting the BOOST pin (Pin 1) to V +, the charge and discharge current is increased and, hence, the frequency is increased by approximately four and a half times. Increasing the frequency will decrease output impedance and ripple for high 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 LTC660 from an external frequency source can be easily achieved by driving Pin 7 and leaving the BOOST pin open, as shown in Figure 6. The output current from Pin 7 is small, typically 1.1µA to 8µA, so a logic gate is capable of driving this current. (A CMOS logic gate can be used to drive the OSC pin.) For 5V applications, a TTL logic gate can be used by simply adding an external pull-up resistor (see Figure 6). Capacitor Selection While the exact values of C1 and C2 are noncritical, good quality, low ESR capacitors are necessary to minimize voltage losses at high currents. For C1 the effect of the ESR of the capacitor will be multiplied by four, due to the fact the switch currents are approximately two times higher than the output current and losses will occur on both the charge and discharge cycle. This means using a capacitor with 1Ω of ESR for C1 will have the same effect as increasing the output impedance of the LTC660 by 4Ω. This represents a significant increase in the voltage losses. For C2 the effect of ESR is less dramatic. A C2 with 1Ω of ESR will increase the output impedance by 1Ω. The size of C2 and the load current will determine the output voltage ripple. It is alternately charged and discharged at a current approximately equal to the output current. This will cause a step function to occur in the output voltage at the switch transitions. For example, for a switching frequency of 5kHz (one-half the nominal 10kHz oscillator frequency) and C2 = 150µF with an ESR of 0.2Ω, ripple is approximately 90mV with a 100mA load current. 7 LTC660 U TYPICAL APPLICATIONS N Negative Voltage Converter Voltage Doubling Figure 7 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 LV pin (Pin 6) is shown grounded, but for V + ≥ 3V, it may be floated, since LV is internally switched to ground (Pin 3) for V + ≥ 3V. Figure 8 shows the LTC660 operating in the voltage doubling mode. The external Schottky (1N5817) diode is for start-up only. The output voltage is 2 • VIN without a load. The diode has no effect on the output voltage. 1 V+ BOOST 1N5817* 1 8 VIN 1.5V TO 5.5V 7 CAP+ OSC LTC660 6 3 GND LV 2 + C1 150µF 4 CAP – VOUT VIN 2.5V TO 5.5V 5 C1 150µF 2 + 3 4 CAP + OSC LTC660 GND LV CAP – VOUT VOUT = –VIN C2 150µF V+ BOOST 8 + 7 VOUT = 2VIN C2 150µF 6 5 * SCHOTTKY DIODE IS FOR START-UP ONLY LTC660 • F08 Figure 8. Voltage Doubler + LTC660 • F07 Figure 7. Voltage Inverter Ultraprecision Voltage Divider The output voltage (Pin 5) characteristics of the circuit are those of a nearly ideal voltage source in series with a 6.5Ω resistor. The 6.5Ω output impedance is composed of two terms: 1) the equivalent switched-capacitor resistance (see Theory of Operation), and 2) a term related to the onresistance of the MOS switches. At an oscillator frequency of 10kHz and C1 = 150µF, the first term is: R EQUIV = (f 1 ) OSC /2 C1 1 5 • 103 • 150 • 10 –6 = + C1 150µF V+ ± 0.002% 2 TMIN ≤ TA ≤ TMAX IL ≤ 100nA + 1 8 2 7 3 4 LTC660 V+ 3V TO 11V 6 5 C2 150µF = 1.3Ω. Notice that the 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 complex, but the dominant effect of the capacitor is clearly shown on the typical curves of output impedance and power efficiency versus frequency. For C1 = C2 = 150µF, the output impedance goes from 6.5Ω at fOSC = 10kHz to 110Ω at fOSC = 100Hz. As the 1/fC term becomes large compared to the switch on-resistance term, the output resistance is determined by 1/fC only. 8 An ultraprecision voltage divider is shown in Figure 9. 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. LTC660 • F09 Figure 9. Ultraprecision Voltage Divider Battery Splitter A common need in many systems is to obtain positive and negative supplies from a single battery or single power supply system. Where current requirements are small, the circuit shown in Figure 10 is a simple solution. It provides symmetrical positive or negative output voltages, both equal to one-half the input voltage. The output voltages are both referenced to Pin 3 (Output Common). LTC660 U TYPICAL APPLICATIONS N VB (9V) 1 2 C1 150µF 3 +VB/2 (4.5V) 7 LTC660 4 6 5 –VB/2 (–4.5V) C2 150µF + OUTPUT COMMON 3V ≤ VB ≤ 11V Additional flexibility of the LTC660 is shown in Figures 11 and 12. Figure 11 shows two LTC660s connected in parallel to provide a lower effective output resistance. If, however, the output resistance is dominated by 1/fC1, increasing the capacitor size (C1) or increasing the frequency will be of more benefit than the paralleling circuit shown. LTC1046 • TA10 Stacking for Higher Voltage Figure 10. Battery Splitter Figure 12 makes use of “stacking” two LTC660s to provide even higher voltages. In Figure 12, a negative voltage doubler or tripler can be achieved depending upon how Pin 8 of the second LTC660 is connected, as shown schematically by the switch. V+ + 1 8 1 2 7 2 3 C1 150µF LTC660 + 6 4 5 3 C1 150µF 8 7 LTC660 4 6 5 VOUT = –V + 1/4 CD4077 + C2 150µF OPTIONAL SYNCHRONIZATION CIRCUIT TO MINIMIZE RIPPLE LTC660 • F11 Figure 11. Paralleling for 200mA Load Current FOR VOUT = –3V + V+ 7 3 4 LTC660 1 150µF 6 5 1 3 –V + 8 7 2 LTC660 2 4 6 5 VOUT 150µF + 150µF 8 2 FOR VOUT = –2V + 150µF + + 1 + + Paralleling for Lower Output Resistance 8 LTC660 • F12 Figure 12. Stacking for High Voltage 9 LTC660 U PACKAGE DESCRIPTION Dimensions in inches (millimeters) unless otherwise noted. N8 Package 8-Lead PDIP (Narrow 0.300) (LTC DWG # 05-08-1510) 0.400* (10.160) MAX 8 7 6 5 1 2 3 4 0.255 ± 0.015* (6.477 ± 0.381) 0.300 – 0.325 (7.620 – 8.255) 0.009 – 0.015 (0.229 – 0.381) ( +0.035 0.325 –0.015 8.255 +0.889 –0.381 ) 0.045 – 0.065 (1.143 – 1.651) 0.065 (1.651) TYP 0.100 ± 0.010 (2.540 ± 0.254) *THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS. MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.010 INCH (0.254mm) 10 0.130 ± 0.005 (3.302 ± 0.127) 0.125 (3.175) 0.020 MIN (0.508) MIN 0.018 ± 0.003 (0.457 ± 0.076) N8 1197 LTC660 U PACKAGE DESCRIPTION Dimensions in inches (millimeters) unless otherwise noted. S8 Package 8-Lead Plastic Small Outline (Narrow 0.150) (LTC DWG # 05-08-1610) 0.189 – 0.197* (4.801 – 5.004) 8 7 6 5 0.150 – 0.157** (3.810 – 3.988) 0.228 – 0.244 (5.791 – 6.197) 1 0.010 – 0.020 × 45° (0.254 – 0.508) 0.008 – 0.010 (0.203 – 0.254) 0.053 – 0.069 (1.346 – 1.752) 0°– 8° TYP 0.016 – 0.050 0.406 – 1.270 0.014 – 0.019 (0.355 – 0.483) 2 3 4 0.004 – 0.010 (0.101 – 0.254) 0.050 (1.270) TYP *DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE **DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE 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. SO8 0996 11 LTC660 U TYPICAL APPLICATIONS N Voltage Inverter 1 V+ BOOST 8 VIN 1.5V TO 5.5V 7 CAP+ OSC LTC660 6 3 GND LV 2 + C1 150µF 4 CAP – VOUT 5 VOUT = –VIN C2 150µF + LTC660 • F07 Voltage Doubler 1N5817* 1 VIN 2.5V TO 5.5V C1 150µF + 2 3 4 V+ BOOST CAP + OSC LTC660 GND CAP – LV VOUT 8 7 + VOUT = 2VIN C2 150µF 6 5 * SCHOTTKY DIODE IS FOR START-UP ONLY LTC660 • F08 RELATED PARTS PART NUMBER OUTPUT CURRENT MAXIMUM VIN COMMENTS LTC660 100mA 6V LTC1046 50mA 6V LTC1044 20mA 9.5V LTC1044A 20mA 13V LTC1144 20mA 20V Highest Voltage LT1054 100mA 16V Adjustable Output LTC1262 30mA 6V 12V Fixed Output LTC1261 10mA 9V – 4V, – 4.5V and Adjustable Outputs Unregulated Output Voltage Highest Current Lowest Cost Regulated Output Voltage All devices are available in plastic 8-lead SO and PDIP packages 12 Linear Technology Corporation LT/GP 0598 2K REV A • PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408)432-1900 ● FAX: (408) 434-0507 ● www.linear-tech.com LINEAR TECHNOLOGY CORPORATION 1995