LTC1046 "Inductorless" 5V to - 5V Converter U FEATURES DESCRIPTIO 50mA Output Current Plug-In Compatible with ICL7660/LTC1044 ROUT = 35 Maximum 300A Maximum No Load Supply Current at 5V Boost Pin (Pin 1) for Higher Switching Frequency 97% Minimum Open-Circuit Voltage Conversion Efficiency 95% Minimum Power Conversion Efficiency Wide Operating Supply Voltage Range: 1.5V to 6V Easy to Use Low Cost U APPLICATIO S Designed to be pin-for-pin and functionally compatible with the ICL7660 and LTC1044, the LTC1046 provides 2.5 times the output drive capability. , LTC and LT are registered trademarks of Linear Technology Corporation. Conversion of 5V to 5V Supplies Precise Voltage Division, VOUT = VIN /2 Supply Splitter, VOUT = VS /2 U The LTC(R)1046 is a 50mA monolithic CMOS switched capacitor voltage converter. It plugs in for the ICL7660/ LTC1044 in 5V applications where more output current is needed. The device is optimized to provide high current capability for input voltages of 6V or less. It trades off operating voltage to get higher output current. The LTC1046 provides several voltage conversion functions: the input voltage can be inverted (VOUT = - VIN), divided (VOUT = VIN/2) or multiplied (VOUT = nVIN). TYPICAL APPLICATIO Output Voltage vs Load Current for V + = 5V -5 TA = 25C Generating - 5V from 5V 2 + 10F 3 4 BOOST V+ CAP + OSC GND CAP - LV VOUT 8 5V INPUT 7 6 5 -5V OUTPUT 10F + 1 1046 TA01 OUTPUT VOLTAGE (V) -4 LTC1046 ICL7660/LTC1044, ROUT = 55 -3 LTC1046, ROUT = 27 -2 -1 0 0 10 20 30 40 LOAD CURRENT, IL (mA) 50 1046 TA02 1046fb 1 LTC1046 W W W AXI U U ABSOLUTE RATI GS (Note 1) Supply Voltage ....................................................... 6.5V Input Voltage on Pins 1, 6 and 7 (Note 2) ............................ - 0.3 < VIN < (V +) + 0.3V Current into Pin 6 .................................................. 20A Output Short Circuit Duration (V + 6V) ............................................... Continuous Operating Temperature Range LTC1046C .................................... 0C TA 70C LTC1046I ................................. - 40C TA 85C LTC1046M (OBSOLETE) ............ - 55C to 125C Storage Temperature Range ............... - 65C to + 150C Lead Temperature (Soldering, 10 sec.)................. 300C U W U PACKAGE/ORDER I FOR ATIO ORDER PART NUMBER ORDER PART NUMBER TOP VIEW TOP VIEW BOOST 1 CAP + 8 LTC1046MJ8 V+ 2 7 OSC GND 3 6 LV CAP - 4 5 VOUT 8 V+ 2 7 OSC GND 3 6 LV 5 VOUT BOOST 1 CAP + CAP - 4 N8 PACKAGE 8-LEAD PDIP J8 PACKAGE 8-LEAD CERDIP LTC1046CN8 LTC1046CS8 LTC1046IN8 LTC1046IS8 S8 PACKAGE 8-LEAD PLASTIC SO S8 PART MARKING TJMAX = 110C, JA = 130C (N8) TJMAX = 150C, JA = 150C (S8) TJMAX = 160C, JA = 100C 1046 1046I OBSOLETE PACKAGE Consider the N8 or S8 for Alternate Source Consult LTC Marketing for parts specified with wider operating temperature ranges. ELECTRICAL CHARACTERISTICS The denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25C. V + = 5V, COSC = 0pF, unless otherwise noted. SYMBOL PARAMETER CONDITIONS IS Supply Current RL = , Pins 1 and 7 No Connection RL = , Pins 1 and 7 No Connection, V+ = 3V V+L Minimum Supply Voltage RL = 5k V+H Maximum Supply Voltage RL = 5k ROUT Output Resistance V+ = 5V, IL = 50mA (Note 3) V+ = 2V, IL = 10mA MIN LTC1046C TYP MAX 165 35 MIN 300 1.5 LTC1046I/M TYP MAX 165 35 1.5 fOSC Oscillator Frequency V+ = 5V (Note 4) V+ = 2V 20 4 35 45 85 A A V 6 27 27 60 300 UNITS 27 27 60 6 V 35 50 90 30 5.5 20 4 30 5.5 kHz kHz PEFF Power Efficiency RL = 2.4k 95 97 95 97 % VOUTEFF Voltage Conversion Efficiency RL = 97 99.9 97 99.9 % IOSC Oscillator Sink or Source Current VOSC = 0V or V+ Pin 1 = 0V Pin 1 = V+ 4.2 15 35 45 4.2 15 40 50 A A 1046fb 2 LTC1046 ELECTRICAL CHARACTERISTICS Note 1: Absolute Maximum Ratings are those values beyond which the life of the 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 sources operating from external supplies be applied prior to power-up of the LTC1046. Note 3: ROUT is measured at TJ = 25C immediately after power-on. 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. U W TYPICAL PERFOR A CE CHARACTERISTICS Output Resistance vs Supply Voltage 1000 TA = 25C V + = 5V IL = 10mA 400 300 OUTPUT RESISTANCE, RO () OUTPUT RESISTANCE, RO () 500 C1 = C2 = 1F 200 C1 = C2 = 10F C1 = C2 = 100F 100 Output Resistance vs Temperature 80 TA = 25C IL = 3mA C1 = C2 = 10F 70 OUTPUT RESISTANCE () Output Resistance vs Oscillator Frequency (Using Test Circuit in Figure 1) COSC = 100pF 100 COSC = 0pF 60 V + = 2V, COSC = 0pF 50 40 V + = 5V, COSC = 0pF 30 20 1k 10k 10 100k 0 1 2 3 4 5 OSCILLATOR FREQUENCY, fOSC (Hz) 8 80 IS 6 50 5 40 4 3 30 TA = 25C V + = 2V C1 = C2 = 10F fOSC = 8kHz 20 10 0 0 1 2 3 4 5 6 7 8 LOAD CURRENT, IL (mA) 9 2 1 0 10 1046 G04 Power Conversion Efficiency vs Oscillator Frequency 100 100 90 90 PEFF 80 80 70 70 60 60 50 50 IS 40 40 30 30 TA = 25C V + = 5V C1 = C2 = 10F fOSC = 30kHz 20 10 0 0 10 20 50 30 40 LOAD CURRENT, IL (mA) 60 20 10 0 70 1046 G05 SUPPLY CURRENT (mA) 7 70 POWER CONVERSION EFFICIENCY, PEFF (%) 9 SUPPLY CURRENT (mA) POWER CONVERSION EFFICIENCY, PEFF (%) 10 PEFF 125 1046 G03 Power Conversion Efficiency vs Load Current for V+ = 5V 100 -25 0 75 100 25 50 AMBIENT TEMPERATURE (C) 1046 G02 Power Conversion Efficiency vs Load Current for V+ = 2V 60 10 -55 7 SUPPLY VOLTAGE, V (V) 1046 G01 90 6 + POWER CONVERSION EFFICIENCY, PEFF (%) 0 100 100 98 A = 100F, 1mA B = 100F, 15mA C = 10F, 1mA D = 10F, 15mA E = 1F, 1mA F = 1F, 15mA A 96 94 92 C V + = 5V TA = 25C C1 = C2 B 90 88 E 86 84 82 80 100 D F 1k 10k 100k OSCILLATOR FREQUENCY, fOSC (Hz) 1M 1046 G06 1046fb 3 LTC1046 U W TYPICAL PERFOR A CE CHARACTERISTICS Output Voltage vs Load Current for V+ = 5V 100 5 TA = 25C 2.0 V + = 2V fOSC = 8kHz 1.5 C1 = C2 = 10F 1.0 TA = 25C V + = 5V fOSC = 30kHz C1 = C2 = 10F 4 3 OUTPUT VOLTAGE (V) OUTPUT VOLTAGE (V) 2.5 0.5 0.0 -0.5 -1.0 Oscillator Frequency as a Function of COSC OSCILLATOR FREQUENCY, fOSC (kHz) Output Voltage vs Load Current for V+ = 2V (Using Test Circuit in Figure 1) 2 1 0 -1 -2 -1.5 -3 SLOPE = 52 -2.0 -4 -2.5 SLOPE = 27 2 4 6 8 10 12 14 16 18 20 LOAD CURRENT, IL (mA) 0 1046 G09 40 OSCILLATOR FREQUENCY, fOSC (kHz) OSCILLATOR FREQUENCY, fOSC (kHz) 10 100 10000 1000 1 EXTERNAL CAPACITOR (PIN 7 TO GND), COSC (pF) Oscillator Frequency vs Temperature TA = 25C COSC = 0pF 10 1 1 PIN 1 = OPEN 1 1046 G08 Oscillator Frequency as a Function of Supply Voltage 0 10 10 20 30 40 50 60 70 80 90 100 LOAD CURRENT, IL (mA) 1046 G07 100 PIN 1 = V + 0.1 -5 0 V + = 5V TA = 25C 2 3 6 4 5 AMBIENT TEMPERATURE (C) 38 36 34 32 30 28 26 -55 7 V + = 5V COSC = 0pF -25 0 75 100 25 50 AMBIENT TEMPERATURE (C) 1046 G10 125 1046 G11 TEST CIRCUIT V + (5V) LTC1046 1 2 + C1 10F 3 4 BOOST CAP + GND CAP - V+ OSC LV VOUT IS 8 7 EXTERNAL OSCILLATOR 6 IL RL 5 COSC VOUT C2 10F + 1046 F01 Figure 1 1046fb 4 LTC1046 U W U UO APPLICATI S I FOR ATIO Theory of Operation To understand the theory of operation of the LTC1046, 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: 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: I = f * q = f * C1(V1 - V2). V1 V2 f RL C1 C2 1046 F02 Examination of Figure 4 shows that the LTC1046 has the same switching action as the basic switched capacitor building block. With the addition of finite switch ON resistance 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 typical curve), this simple theory will explain how the LTC1046 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 power efficiency will drop. The typical curves for power efficiency versus frequency show this effect for various capacitor values. 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. Figure 2. Switched Capacitor Building Block V+ (8) Rewriting in terms of voltage and impedance equivalence, V1 - V 2 I= = . REQUIV 1 / fC1 ) C2 RL CAP - (4) VOUT (5) C2 + V2 +2 OSC (7) LV (6) V1 + C1 OSC REQUIV REQUIV = 1 fC1 3x (1) A new variable, REQUIV, has been defined such that REQUIV = 1/fC1. Thus, the equivalent circuit for the switched capacitor network is as shown in Figure 3. SW2 CAP + (2) BOOST V1 - V 2 ( SW1 CLOSED WHEN V + > 3.0V GND (3) 1046 F04 Figure 4. LTC1046 Switched Capacitor Voltage Converter Block Diagram 1046 F03 Figure 3. Switched Capacitor Equivalent Circuit 1046fb 5 LTC1046 U W U UO APPLICATI S I FOR ATIO LV (Pin 6) The internal logic of the LTC1046 runs between V+ and LV (Pin 6). For V+ greater than or equal to 3V, an internal switch shorts LV to GND (Pin 3). For V+ less than 3V, the LV pin should be tied to ground. For V+ greater than or equal to 3V, the LV pin can be tied to ground or left floating. OSC (Pin 7) and BOOST (Pin 1) The switching frequency can be raised, lowered or driven from an external source. Figure 5 shows a functional diagram of the oscillator circuit. By connecting the BOOST (Pin 1) to V+, the charge and discharge current is increased and, hence, the frequency is increased by approximately three 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 in conjunction with external capacitance on Pin 7 allows user selection of the frequency over a wide range. Driving the LTC1046 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 15A, so a logic gate is capable of driving this current. The choice of using a CMOS V+ 2I I 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 5. 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 CIN and COUT are noncritical, good quality, low ESR capacitors such as solid tantalum are necessary to minimize voltage losses at high currents. For CIN the effect of the ESR of the capacitor will be multiplied by four, due to the fact that switch currents are approximately two times higher than output current, and losses will occur on both the charge and discharge cycle. This means that using a capacitor with 1 of ESR for CIN will have the same effect as increasing the output impedance of the LTC1046 by 4. This represents a significant increase in the voltage losses. For COUT the effect of ESR is less dramatic. COUT is alternately charged and discharged at a current approximately equal to the output current, and the ESR of the capacitor will cause a step function to occur, in the output ripple, at the switch transitions. This step function will degrade the output regulation for changes in output load current, and should be avoided. Realizing that large value tantalum capacitors can be expensive, a technique that can be used is to parallel a smaller tantalum capacitor with a large aluminum electrolytic capacitor to gain both low ESR and reasonable cost. Where physical size is a concern some of the newer chip type surface mount tantalum capacitors can be used. These capacitors are normally rated at working voltages in the 10V to 20V range and exhibit very low ESR (in the range of 0.1). BOOST (1) REQUIRED FOR TTL LOGIC V+ LTC1046 NC OSC (7) 14pF 2 SCHMITT TRIGGER + C1 3 4 BOOST CAP + GND V+ OSC LV CAP - VOUT 8 100k 7 OSC INPUT 6 5 -(V +) C2 I + 2I LV (6) 1 1046 F05 1046 F06 Figure 5. Oscillator Figure 6. External Clocking 1046fb 6 LTC1046 UO TYPICAL APPLICATI S Negative Voltage Converter 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 GND (Pin 3) for V+ 3V. The output voltage (Pin 5) characteristics of the circuit are those of a nearly ideal voltage source in series with an 27 resistor. The 27 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. At an oscillator frequency of 30kHz and C1 = 10F, the first term is: the typical curves of output impedance and power efficiency versus frequency. For C1 = C2 = 10F, the output impedance goes from 27 at fOSC = 30kHz to 225 at fOSC = 1kHz. As the 1/fC term becomes large compared to switch ON resistance term, the output resistance is determined by 1/fC only. Voltage Doubling Figure 8 shows a two diode, capacitive voltage doubler. With a 5V input, the output is 9.1V with no load and 8.2V with a 10mA load. LTC1046 1 2 3 4 V+ BOOST CAP + OSC LV GND CAP - VOUT V+ 1.5V TO 6V 8 + 7 VD 6 REQUIRED FOR V + < 3V 5 + VD + VOUT = 2 (VIN - 1) + 10F REQUIV = 1 (fOSC / 2) * C1 = 10F 1046 F08 Figure 8. Voltage Doubler 1 = 6.7. 15 * 103 * 10 * 10 -6 Ultraprecision Voltage Divider Notice that the equation for REQUIV is not a capacitive reactance equation (XC = 1/C) and does not contain a 2 term. An ultraprecision voltage divider is shown in Figure 9. To achieve the 0.0002% accuracy indicated, the load current should be kept below 100nA. However, with a slight loss in accuracy, the load current can be increased. The exact expression for output impedance is complex, but the dominant effect of the capacitor is clearly shown on LTC1046 1 LTC1046 1 2 + 4 CAP + GND CAP - V+ OSC LV VOUT V+ 1.5V TO 6V 8 7 REQUIRED FOR V + < 3V 5 VOUT = -V + 10F TMIN TA TMAX 2 + C1 3 10F 6 + 10F 3 BOOST 1046 F07 Figure 7. Negative Voltage Converter V+ 0.002% 2 TMIN TA TMAX IL 100nA 4 + BOOST CAP + GND CAP - V+ OSC LV VOUT 8 7 V+ 3V TO 12V 6 5 1046 F09 C2 10F REQUIRED FOR V + < 6V Figure 9. Ultraprecision Voltage Divider 1046fb 7 LTC1046 UO TYPICAL APPLICATI S Battery Splitter equal to one half the input voltage. The output voltages are both referenced to Pin 3 (output common). If the input voltage between Pin 8 and Pin 5 is less than 6V, Pin 6 should also be connected to Pin 3, as shown by the dashed line. 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 Paralleling for Lower Output Resistance Additional flexibility of the LTC1046 is shown in Figures 11 and 12. Figure 11 shows two LTC1046s 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 1 VB 9V 2 C1 10F + 3 4 V+ BOOST CAP + OSC LV GND CAP - VOUT 8 +VB /2 4.5V 7 REQUIRED FOR VB < 6V 6 5 -VB /2 -4.5V + 3V VB 12V Figure 12 makes use of "stacking" two LTC1046s 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 LTC1046 is connected, as shown schematically by the switch. C2 10F OUTPUT COMM0N 1046 F10 Figure 10. Battery Splitter V+ LTC1046 1 2 C1 10F + 3 4 LTC1046 V+ BOOST CAP + OSC LV GND CAP - VOUT 8 1 7 2 6 C1 10F 5 + 3 4 V+ BOOST CAP + OSC LV GND CAP - VOUT 8 7 6 5 VOUT = -(V +) 1/4 CD4077 + OPTIONAL SYNCHRONIZATION CIRCUIT TO MINIMIZE RIPPLE C2 20F 1046 F11 Figure 11. Paralleling for 100mA Load Current FOR VOUT = -3V + LTC1046 1 + 10F 3 4 BOOST CAP + GND CAP - OSC LV VOUT + 2 C1 10F 8 V+ 7 LTC1046 1 2 6 3 5 4 -(V +) 10F FOR VOUT = -2V + BOOST CAP + GND CAP - V+ OSC LV VOUT 8 7 6 5 VOUT 10F + V+ + 1046 F12 Figure 12. Stacking for Higher Voltage 1046fb 8 LTC1046 U PACKAGE DESCRIPTIO J8 Package 8-Lead CERDIP (Narrow .300 Inch, Hermetic) (Reference LTC DWG # 05-08-1110) CORNER LEADS OPTION (4 PLCS) .023 - .045 (0.584 - 1.143) HALF LEAD OPTION .045 - .068 (1.143 - 1.650) FULL LEAD OPTION .005 (0.127) MIN .405 (10.287) MAX 8 7 6 5 .025 (0.635) RAD TYP .220 - .310 (5.588 - 7.874) 1 2 .300 BSC (7.62 BSC) 3 4 .200 (5.080) MAX .015 - .060 (0.381 - 1.524) .008 - .018 (0.203 - 0.457) 0 - 15 NOTE: LEAD DIMENSIONS APPLY TO SOLDER DIP/PLATE OR TIN PLATE LEADS .045 - .065 (1.143 - 1.651) .014 - .026 (0.360 - 0.660) .100 (2.54) BSC .125 3.175 MIN J8 0801 OBSOLETE PACKAGE 1046fb 9 LTC1046 U PACKAGE DESCRIPTIO N8 Package 8-Lead PDIP (Narrow .300 Inch) (Reference LTC DWG # 05-08-1510) .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) .130 .005 (3.302 0.127) .065 (1.651) TYP .100 (2.54) BSC .120 (3.048) .020 MIN (0.508) MIN .018 .003 (0.457 0.076) N8 1002 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) 1046fb 10 LTC1046 U PACKAGE DESCRIPTIO S8 Package 8-Lead Plastic Small Outline (Narrow .150 Inch) (Reference LTC DWG # 05-08-1610) .189 - .197 (4.801 - 5.004) NOTE 3 .045 .005 .050 BSC 8 .245 MIN 7 6 5 .160 .005 .150 - .157 (3.810 - 3.988) NOTE 3 .228 - .244 (5.791 - 6.197) .030 .005 TYP 1 RECOMMENDED SOLDER PAD LAYOUT .010 - .020 x 45 (0.254 - 0.508) .008 - .010 (0.203 - 0.254) 3 4 .053 - .069 (1.346 - 1.752) .004 - .010 (0.101 - 0.254) 0- 8 TYP .016 - .050 (0.406 - 1.270) NOTE: 1. DIMENSIONS IN 2 .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) .050 (1.270) BSC SO8 0303 1046fb 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. 11 LTC1046 RELATED PARTS PART NUMBER DESCRIPTION COMMENTS LTC1044A 12V CMOS Voltage Converter Doubler or Inverter, 20mA IOUT, 1.5V to 12V Input Range LT(R)1054 Switched Capacitor Voltage Converter with Regulator Doubler or Inverter, 100mA IOUT, SO-8 Package LTC1550 Low Noise, Switched Capacitor Regulated Inverter < 1mVP-P Output Ripple, 900kHz Operation, SO-8 Package LT1611 1.4MHz Inverting Switching Regulator 5V to -5V at 150mA, Low Output Noise, SOT-23 Package LT1617 Micropower Inverting Switching Regulator 5V to - 5V at 20A Supply Current, SOT-23 Package LTC1754-5 Micropower Regulated 5V Charge Pump in SOT-23 5V/50mA, 13A Supply Current, 2.7V to 5.5V Input Range 1046fb 12 Linear Technology Corporation LT/TP 0403 1K REV B * PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 FAX: (408) 434-0507 www.linear.com LINEAR TECHNOLOGY CORPORATION 1991