FEATURES DESCRIPTIO APPLICATIO S TYPICAL APPLICATIO. LTC1046 Inductorless 5V to 5V Converter

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1 LTC Inductorless V to V Converter FEATRES ma Output Current Plug-In Compatible with ICL/LTC R OT = Ω Maximum µa Maximum No Load Supply Current at V Boost Pin (Pin ) for Higher Switching Frequency 9% Minimum Open-Circuit Voltage Conversion Efficiency 9% Minimum Power Conversion Efficiency Wide Operating Supply Voltage Range:.V to V Easy to se Low Cost APPLICATIO S Conversion of V to ±V Supplies Precise Voltage Division, = V IN / Supply Splitter, = ±V S / DESCRIPTIO The LTC is a ma monolithic CMOS switched capacitor voltage converter. It plugs in for the ICL/ LTC in V applications where more output current is needed. The device is optimized to provide high current capability for input voltages of V or less. It trades off operating voltage to get higher output current. The LTC provides several voltage conversion functions: the input voltage can be inverted ( = V IN ), divided ( = V IN/ ) or multiplied ( = ± nv IN ). Designed to be pin-for-pin and functionally compatible with the ICL and LTC, the LTC provides. times the output drive capability., LTC and LT are registered trademarks of Linear Technology Corporation. TYPICAL APPLICATIO Output Voltage vs Load Current for V = V Generating V from V T A = C µf LTC BOOST CAP V V INPT PT µf OTPT VOLTAGE (V) ICL/LTC, R OT = Ω LTC, R OT = Ω TA LOAD CRRENT, I L (ma) TA fb

2 LTC ABSOLTE AXI RATI GS W W W Supply Voltage....V Input Voltage on Pins, and (Note ).... < V IN < (V ).V Current into Pin... µa Output Short Circuit Duration (V V)...Continuous (Note ) Operating Temperature Range LTCC... C T A C LTCI... C T A C LTCM (OBSOLETE)... C to C Storage Temperature Range... C to C Lead Temperature (Soldering, sec.)... C PACKAGE/ORDER I FOR BOOST CAP TOP VIEW J PACKAGE -LEAD CERDIP T JMAX = C, θ JA = C V W OBSOLETE PACKAGE Consider the N or S for Alternate Source ATIO ORDER PART NMBER LTCMJ Consult LTC Marketing for parts specified with wider operating temperature ranges. BOOST CAP N PACKAGE -LEAD PDIP TOP VIEW T JMAX = C, θ JA = C (N) T JMAX = C, θ JA = C (S) V S PACKAGE -LEAD PLASTIC SO ORDER PART NMBER LTCCN LTCCS LTCIN LTCIS S PART MARKING I ELECTRICAL CHARACTERISTICS The denotes the specifications which apply over the full operating temperature range, otherwise specifications are at T A = C. V = V, C = pf, unless otherwise noted. LTCC LTCI/M SYMBOL PARAMETER CONDITIONS MIN TYP MAX MIN TYP MAX NITS I S Supply Current R L =, Pins and No Connection µa R L =, Pins and No Connection, µa V = V V L Minimum Supply Voltage R L = kω.. V V H Maximum Supply Voltage R L = kω V R OT Output Resistance V = V, I L = ma (Note ) Ω Ω V = V, I L = ma 9 Ω f Oscillator Frequency V = V (Note ) khz V = V.. khz P EFF Power Efficiency R L =.kω % EFF Voltage Conversion R L = % Efficiency I Oscillator Sink or Source V = V or V Current Pin = V.. µa Pin = V µa fb

3 LTC ELECTRICAL CHARACTERISTICS Note : Absolute Maximum Ratings are those values beyond which the life of the device may be impaired. Note : 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 LTC. Note : R OT is measured at T J = C immediately after power-on. Note : f is tested with C = pf to minimize the effects of test fixture capacitance loading. The pf frequency is correlated to this pf test point, and is intended to simulate the capacitance at pin when the device is plugged into a test socket and no external capacitor is used. TYPICAL PERFOR A CE CHARACTERISTICS (sing Test Circuit in Figure ) W OTPT RESISTANCE, R O (Ω) Output Resistance vs Output Resistance vs Output Resistance vs Oscillator Frequency Supply Voltage Temperature C = C = µf C = C = µf T A = C V = V I L = ma C = C = µf OTPT RESISTANCE, R O (Ω) T A = C I L = ma C = pf C = pf OTPT RESISTANCE (Ω) C = C = µf V = V, C = pf V = V, C = pf k k k ILLATOR FREQENCY, f (Hz) SPPLY VOLTAGE, V (V) AMBIENT TEMPERATRE ( C) G G G POWER CONVERSION EFFICIENCY, P EFF (%) 9 Power Conversion Efficiency vs Power Conversion Efficiency vs Power Conversion Efficiency vs Load Current for V = V Load Current for V = V Oscillator Frequency P EFF 9 I S T A = C V = V C = C = µf f = khz 9 LOAD CRRENT, I L (ma) SPPLY CRRENT (ma) POWER CONVERSION EFFICIENCY, P EFF (%) 9 9 P EFF I S T A = C V = V C = C = µf f = khz LOAD CRRENT, I L (ma) SPPLY CRRENT (ma) POWER CONVERSION EFFICIENCY, P EFF (%) A C B E D A = µf, ma B = µf, ma C = µf, ma D = µf, ma E = µf, ma F = µf, ma V = V T A = C C = C k k k M ILLATOR FREQENCY, f (Hz) F G G G fb

4 LTC TYPICAL PERFOR A W CE CHARACTERISTICS (sing Test Circuit in Figure ) OTPT VOLTAGE (V) Output Voltage vs Load Current Output Voltage vs Load Current Oscillator Frequency as a for V = V for V = V Function of C T A = C V = V f = khz C = C = µf SLOPE = Ω LOAD CRRENT, I L (ma) OTPT VOLTAGE (V) T A = C V = V f = khz C = C = µf SLOPE = Ω 9 LOAD CRRENT, I L (ma) ILLATOR FREQENCY, f (khz) PIN = OPEN PIN = V V = V T A = C. EXTERNAL CAPACITOR (PIN TO ), C (pf) G G G9 ILLATOR FREQENCY, f (khz) Oscillator Frequency as a Function of Supply Voltage T A = C C = pf ILLATOR FREQENCY, f (khz) Oscillator Frequency vs Temperature V = V C = pf AMBIENT TEMPERATRE ( C) AMBIENT TEMPERATRE ( C) G G TEST CIRCIT C µf LTC BOOST CAP V C EXTERNAL ILLATOR V (V) R L I S I L C µf F Figure fb

5 LTC APPLICATI O Theory of Operation S I FOR W ATIO To understand the theory of operation of the LTC, a review of a basic switched capacitor building block is helpful. In Figure, when the switch is in the left position, capacitor C will charge to voltage V. The total charge on C will be q = CV. The switch then moves to the right, discharging C to voltage V. After this discharge time, the charge on C is q = CV. Note that charge has been transferred from the source, V, to the output, V. The amount of charge transferred is: q = q q = C(V V). If the switch is cycled f times per second, the charge transfer per unit time (i.e., current) is: I = f q = f C(V V). V f C Figure. Switched Capacitor Building Block C R L F V Examination of Figure shows that the LTC 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 LTC 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 /fc 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. Rewriting in terms of voltage and impedance equivalence, V V I = / fc ( ) = V V V. R EQIV A new variable, R EQIV, has been defined such that R EQIV = /fc. Thus, the equivalent circuit for the switched capacitor network is as shown in Figure. R EQIV V BOOST x () () () V () φ φ CLOSED WHEN V >.V SW CAP () () () C SW F () C R EQIV = fc C R L Figure. LTC Switched Capacitor Voltage Converter Block Diagram F Figure. Switched Capacitor Equivalent Circuit fb

6 LTC APPLICATI (Pin ) O S I FOR W ATIO The internal logic of the LTC runs between V and (Pin ). For V greater than or equal to V, an internal switch shorts to (Pin ). For V less than V, the pin should be tied to ground. For V greater than or equal to V, the pin can be tied to ground or left floating. (Pin ) and BOOST (Pin ) The switching frequency can be raised, lowered or driven from an external source. Figure shows a functional diagram of the oscillator circuit. By connecting the BOOST (Pin ) 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 with more capacitance will lower the frequency. sing the BOOST pin in conjunction with external capacitance on Pin allows user selection of the frequency over a wide range. Driving the LTC from an external frequency source can be easily achieved by driving Pin and leaving the BOOST pin open, as shown in Figure. The output current from Pin is small, typically µa, so a logic gate is capable of driving this current. The choice of using a CMOS BOOST () () I I V I I () pf F SCHMITT TRIGGER logic gate is best because it can operate over a wide supply voltage range (V to V) and has enough voltage swing to drive the internal Schmitt trigger shown in Figure. For V applications, a TTL logic gate can be used by simply adding an external pull-up resistor (see Figure ). Capacitor Selection While the exact values of C IN and C OT are noncritical, good quality, low ESR capacitors such as solid tantalum are necessary to minimize voltage losses at high currents. For C IN 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 Ω of ESR for C IN will have the same effect as increasing the output impedance of the LTC by Ω. This represents a significant increase in the voltage losses. For C OT the effect of ESR is less dramatic. C OT 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 V to V range and exhibit very low ESR (in the range of.ω). C REQIRED FOR TTL LOGIC LTC NC BOOST V CAP k C (V ) V F INPT Figure. Oscillator Figure. External Clocking fb

7 LTC TYPICAL APPLICATI Negative Voltage Converter O Figure 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 pin (Pin ) is shown grounded, but for V V, it may be floated, since is internally switched to (Pin ) for V V. The output voltage (Pin ) characteristics of the circuit are those of a nearly ideal voltage source in series with an Ω resistor. The Ω output impedance is composed of two terms: ) the equivalent switched capacitor resistance (see Theory of Operation), and ) a term related to the ON resistance of the MOS switches. At an oscillator frequency of khz and C = µf, the first term is: S the typical curves of output impedance and power efficiency versus frequency. For C = C = µf, the output impedance goes from Ω at f = khz to Ω at f = khz. As the /fc term becomes large compared to switch ON resistance term, the output resistance is determined by /fc only. Voltage Doubling Figure shows a two diode, capacitive voltage doubler. With a V input, the output is 9.V with no load and.v with a ma load. LTC BOOST V CAP REQIRED FOR V D VD V < V µf µf V.V TO V = (V IN ) R = EQIV f / ( ) = C =. Ω. Notice that the equation for R EQIV is not a capacitive reactance equation (X C = /ωc) and does not contain a π term. The exact expression for output impedance is complex, but the dominant effect of the capacitor is clearly shown on µf LTC BOOST V CAP T MIN T A T MAX µf F Figure. Negative Voltage Converter V.V TO V REQIRED FOR V < V = V Figure. Voltage Doubler ltraprecision Voltage Divider Figure 9. ltraprecision Voltage Divider F An ultraprecision voltage divider is shown in Figure 9. To achieve the.% accuracy indicated, the load current should be kept below na. However, with a slight loss in accuracy, the load current can be increased. C µf ±.% V T MIN T A T MAX I L na LTC BOOST V CAP C µf V V TO V F9 REQIRED FOR V < V fb

8 LTC TYPICAL APPLICATI Battery Splitter O 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 is a simple solution. It provides symmetrical positive or negative output voltages, both V B 9V C µf V V B V LTC BOOST V CAP S Figure. Battery Splitter REQIRED FOR V B < V C µf OTPT COMMN F V B /.V V B /.V equal to one half the input voltage. The output voltages are both referenced to Pin (output common). If the input voltage between Pin and Pin is less than V, Pin should also be connected to Pin, as shown by the dashed line. Paralleling for Lower Output Resistance Additional flexibility of the LTC is shown in Figures and. Figure shows two LTCs connected in parallel to provide a lower effective output resistance. If, however, the output resistance is dominated by /fc, increasing the capacitor size (C) or increasing the frequency will be of more benefit than the paralleling circuit shown. Figure makes use of stacking two LTCs to provide even higher voltages. In Figure, a negative voltage doubler or tripler can be achieved depending upon how Pin of the second LTC is connected, as shown schematically by the switch. C µf LTC BOOST CAP V C µf LTC BOOST CAP V V = (V ) / CD C µf OPTIONAL SYNCHRONIZATION CIRCIT TO MINIMIZE RIPPLE F Figure. Paralleling for ma Load Current µf V LTC BOOST V CAP (V ) µf C µf FOR = V LTC BOOST V CAP FOR = V µf F Figure. Stacking for Higher Voltage fb

9 LTC PACKAGE DESCRIPTIO J Package -Lead CERDIP (Narrow. Inch, Hermetic) (Reference LTC DWG # --).. (..) FLL LEAD OPTION. BSC (. BSC) CORNER LEADS OPTION ( PLCS).. (..) HALF LEAD OPTION. (.) MIN. (.) RAD TYP. (.) MAX.. (..). (.) MAX.. (..).. (..) NOTE: LEAD DIMENSIONS APPLY TO SOLDER DIP/PLATE OR TIN PLATE LEADS.. (..).. (..). (.) BSC.. MIN J OBSOLETE PACKAGE fb 9

10 LTC PACKAGE DESCRIPTIO N Package -Lead PDIP (Narrow. Inch) (Reference LTC DWG # --).* (.) MAX. ±.* (. ±.).. (..).. (..). ±. (. ±.).. (..) ( ). (.) TYP. (.) BSC NOTE: INCHES. DIMENSIONS ARE MILLIMETERS *THESE DIMENSIONS DO NOT INCLDE MOLD FLASH OR PROTRSIONS. MOLD FLASH OR PROTRSIONS SHALL NOT EXCEED. INCH (.mm). (.) MIN. ±. (. ±.). (.) MIN N fb

11 LTC PACKAGE DESCRIPTIO S Package -Lead Plastic Small Outline (Narrow. Inch) (Reference LTC DWG # --). BSC. ±..9.9 (..) NOTE. MIN. ±... (.9.9).. (..9) NOTE. ±. TYP RECOMMENDED SOLDER PAD LAYOT.. (..).. (..) TYP..9 (..).. (..).. (..) NOTE: INCHES. DIMENSIONS IN (MILLIMETERS)..9 (..) TYP. DRAWING NOT TO SCALE. THESE DIMENSIONS DO NOT INCLDE MOLD FLASH OR PROTRSIONS. MOLD FLASH OR PROTRSIONS SHALL NOT EXCEED." (.mm). (.) BSC SO 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. fb

12 LTC RELATED PARTS PART NMBER DESCRIPTION COMMENTS LTCA V CMOS Voltage Converter Doubler or Inverter, ma I OT,.V to V Input Range LT Switched Capacitor Voltage Converter with Regulator Doubler or Inverter, ma I OT, SO- Package LTC Low Noise, Switched Capacitor Regulated Inverter <mv P-P Output Ripple, 9kHz Operation, SO- Package LT.MHz Inverting Switching Regulator V to V at ma, Low Output Noise, SOT- Package LT Micropower Inverting Switching Regulator V to V at µa Supply Current, SOT- Package LTC- Micropower Regulated V Charge Pump in SOT- V/mA, µa Supply Current,.V to.v Input Range Linear Technology Corporation McCarthy Blvd., Milpitas, CA 9- () -9 FAX: () - fb LT/TP K REV B PRINTED IN SA LINEAR TECHNOLOGY CORPORATION 99

DESCRIPTIO TYPICAL APPLICATIO. LTC1383 5V Low Power RS232 Transceiver FEATURES APPLICATIO S

DESCRIPTIO TYPICAL APPLICATIO. LTC1383 5V Low Power RS232 Transceiver FEATURES APPLICATIO S LTC V Low Power RS Transceiver FEATRES Operates from a Single V Supply Low Supply Current: I CC = µa ESD Protection Over ±kv Available in -Pin SOIC Narrow Package ses Small Capacitors: Operates to kbaud