156869 TI | Alldatasheet
Document overview
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Technical content
Features
n Inverts Input Supply Voltage n SOT23-6 Package n 12Ω Typical Output Impedance n 91% Typical Conversion Efficiency at 40 mA n 1µA Typical Shutdown Current
Applications
n Operational Amplifier Power Suppliers n Interface Power Suppliers n Handheld Instruments Basic Application Circuits Voltage Inverter 10003101 +5V to −10V Converter 10003125 September 2005 LM2664 Switched Capacitor Voltage Converter © 2005 National Semiconductor Corporation DS100031 www.national.com
Absolute Maximum Ratings (Note 1) If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. Supply Voltage (V+ to GND, or GND to OUT) 5.8V SD (GND − 0.3V) to (V+ + 0.3V) V+ and OUT Continuous Output Current 50 mA Output Short-Circuit Duration to GND (Note 2) 1 sec. Continuous Power Dissipation (T A = 25˚C)(Note 3) 600 mW TJMax(Note 3) 150˚C θJA (Note 3) 210˚C/W Operating Junction Temperature Range −40˚ to 85˚C Storage Temperature Range −65˚C to +150˚C Lead Temp. (Soldering, 10 seconds) 300˚C ESD Rating 2kV
Electrical Characteristics
Limits in standard typeface are for T J = 25˚C, and limits in boldface type apply over the full operating temperature range. Un- less otherwise specified: V+ = 5V, C 1 =C 2 = 3.3 µF. (Note 4) Symbol Parameter Condition Min (Note 5) Typ (Note 6) Max (Note 5) Units V+ Supply Voltage 1.8 5.5 V IQ Supply Current No Load 220 500 µA ISD Shutdown Supply Current 1 µA VSD Shutdown Pin Input Voltage Normal Operation 2.0 (Note 7) VShutdown Mode 0.8 (Note 8) IL Output Current 40 mA RSW Sum of the R ds(on)of the four internal MOSFET switches IL =4 0m A 4 8 Ω ROUT Output Resistance (Note 9) I L =4 0m A 1 2 25 Ω fOSC Oscillator Frequency (Note 10) 80 160 kHz fSW Switching Frequency (Note 10) 40 80 kHz PEFF Power Efficiency R L (1.0k) between GND and OUT 90 94 IL =4 0m At oG N D 9 1 VOEFF Voltage Conversion Efficiency No Load 99 99.96 % Note 1: Absolute maximum ratings indicate limits beyond which damage to the device may occur. Electrical specifications do not apply when operating the devi ce beyond its rated operating conditions. Note 2: OUT may be shorted to GND for one second without damage. However, 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+, or device may be damaged. Note 3: The maximum allowable power dissipation is calculated by using P DMax =( TJMax −T A)/θJA, where TJMax is the maximum junction temperature, T A is the ambient temperature, and θJA is the junction-to-ambient thermal resistance of the specified package. Note 4: In the test circuit, capacitors C 1 and C2 are 3.3 µF, 0.3Ω maximum ESR capacitors. Capacitors with higher ESR will increase output resistance, reduce output voltage and efficiency. Note 5: Min. and Max. limits are guaranteed by design, test, or statistical analysis. Note 6: Typical numbers are not guaranteed but represent the most likely norm. Note 7: The minimum input high for the shutdown pin equals 40% of V+. Note 8: The maximum input low for the shutdown pin equals 20% of V+. Note 9: Specified output resistance includes internal switch resistance and capacitor ESR. See the details in the application information for simple negative voltage converter. Note 10: The output switches operate at one half of the oscillator frequency, f OSC =2 fSW. LM2664 www.national.com 2
*C1 and C2 are 3.3 µF, SC series OS-CON capacitors. FIGURE 1. LM2664 Test Circuit
Typical Performance Characteristics (Circuit of Figure 1, V+ = 5V unless otherwise specified) (Continued) Output Voltage Drop vs Load Current Efficiency vs Load Current 10003116 10003117 Oscillator Frequency vs Supply Voltage Oscillator Frequency vs Temperature 10003118 10003119 Shutdown Supply Current vs Temperature 10003120 LM2664 www.national.com 4
6-Lead Small Outline Package (M6) 10003104 Top View With Package Marking 10003122 Actual Size
Ordering Information
Order Number Package Number Package Marking Supplied as LM2664M6 MA06A SO3A (Note 11) Tape and Reel (1000 units/rail) LM2664M6X MA06A SO3A (Note 11) Tape and Reel (3000 units/rail) Note 11: The first letter "S" identifies the part as a switched capacitor converter. The next two numbers are the device number. The fourth letter "A" indicates the grade. Only one grade is available. Larger quantity reels are available upon request. Pin Descriptions Pin Name Function 1 GND Power supply ground input. 2 OUT Negative voltage output. 3 CAP− Connect this pin to the negative terminal of the charge-pump capacitor. 4S D Shutdown control pin, tie this pin to V+ in normal operation, and to GND for shutdown. 5 V+ Power supply positive voltage input. 6 CAP+ Connect this pin to the positive terminal of the charge-pump capacitor. Circuit Description The LM2664 contains four large CMOS switches which are switched in a sequence to invert the input supply voltage. Energy transfer and storage are provided by external capaci- tors. Figure 2 illustrates the voltage conversion scheme. When S 1 and S 3 are closed, C 1 charges to the supply voltage V+. During this time interval, switches S2 and S4 are open. In the second time interval, S1 and S3 are open; at the same time, S2 and S4 are closed, C1 is charging C2. After a number of cycles, the voltage across C 2 will be pumped to V+. Since the anode of C2 is connected to ground, the output at the cathode of C 2 equals −(V+) when there is no load current. The output voltage drop when a load is added is determined by the parasitic resistance (R ds(on) of the MOS- FET switches and the ESR of the capacitors) and the charge transfer loss between capacitors. Details will be discussed in the following application information section. 10003105 FIGURE 2. Voltage Inverting Principle
Application Information
SIMPLE NEGATIVE VOLTAGE CONVERTER The main application of LM2664 is to generate a negative supply voltage. The voltage inverter circuit uses only two external capacitors as shown in the Basic Application Cir- cuits. The range of the input supply voltage is 1.8V to 5.5V. The output characteristics of this circuit can be approximated by an ideal voltage source in series with a resistance. The voltage source equals −(V+). The output resistance R out is a function of the ON resistance of the internal MOSFET switches, the oscillator frequency, the capacitance and ESR of C 1 and C 2. Since the switching current charging and discharging C1 is approximately twice as the output current, the effect of the ESR of the pumping capacitor C 1 will be multiplied by four in the output resistance. The output ca- pacitor C 2 is charging and discharging at a current approxi- mately equal to the output current, therefore, its ESR only counts once in the output resistance. A good approximation of R out is: where RSW is the sum of the ON resistance of the internal MOSFET switches shown in Figure 2. High capacitance, low ESR capacitors will reduce the output resistance. The peak-to-peak output voltage ripple is determined by the oscillator frequency, the capacitance and ESR of the output capacitor C Again, using a low ESR capacitor will result in lower ripple. SHUTDOWN MODE A shutdown (SD ) pin is available to disable the device and reduce the quiescent current to 1µA. Applying a voltage less than 20% of V+ to the SD pin will bring the device into shutdown mode. While in normal operating mode, the pin is connected to V+. CAPACITOR SELECTION As discussed in the Simple Negative Voltage Converter section, the output resistance and ripple voltage are depen- dent on the capacitance and ESR values of the external capacitors. The output voltage drop is the load current times the output resistance, and the power efficiency is Where IQ(V+) is the quiescent power loss of the IC device, and IL 2Rout is the conversion loss associated with the switch on-resistance, the two external capacitors and their ESRs. The selection of capacitors is based on the specifications of the dropout voltage (which equals I out Rout), the output volt- age ripple, and the converter efficiency. Low ESR capacitors (Table 1) are recommended to maximize efficiency, reduce the output voltage drop and voltage ripple. Low ESR Capacitor Manufacturers Manufacturer Phone Capacitor Type Nichicon Corp. (708)-843-7500 PL & PF series, through-hole aluminum electrolytic AVX Corp. (803)-448-9411 TPS series, surface-mount tantalum Sprague (207)-324-4140 593D, 594D, 595D series, surface-mount tantalum Sanyo (619)-661-6835 OS-CON series, through-hole aluminum electrolytic Murata (800)-831-9172 Ceramic chip capacitors Taiyo Yuden (800)-348-2496 Ceramic chip capacitors Tokin (408)-432-8020 Ceramic chip capacitors LM2664 www.national.com 6
Physical Dimensions inches (millimeters) unless otherwise noted 6-Lead Small Outline Package (M6) For Order Numbers, refer to the table in the "Ordering Information" section of this document. National does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and National reserves the right at any time without notice to change said circuitry and specifications. For the most current product information visit us at www.national.com. LIFE SUPPORT POLICY NATIONAL’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT AND GENERAL COUNSEL OF NATIONAL SEMICONDUCTOR CORPORATION. As used herein: 1. Life support devices or systems are devices or systems which, (a) are intended for surgical implant into the body, or (b) support or sustain life, and whose failure to perform when properly used in accordance with instructions for use provided in the labeling, can be reasonably expected to result in a significant injury to the user. 2. A critical component is any component of a life support device or system whose failure to perform can be reasonably expected to cause the failure of the life support device or system, or to affect its safety or effectiveness. BANNED SUBSTANCE COMPLIANCE National Semiconductor manufactures products and uses packing materials that meet the provisions of the Customer Products Stewardship Specification (CSP-9-111C2) and the Banned Substances and Materials of Interest Specification (CSP-9-111S2) and contain no ‘‘Banned Substances’’ as defined in CSP-9-111S2. Leadfree products are RoHS compliant. National Semiconductor Americas Customer Support Center Email: new.feedback@nsc.com Tel: 1-800-272-9959 National Semiconductor Europe Customer Support Center Fax: +49 (0) 180-530 85 86 Email: europe.support@nsc.com Deutsch Tel: +49 (0) 69 9508 6208 English Tel: +44 (0) 870 24 0 2171 Français Tel: +33 (0) 1 41 91 8790 National Semiconductor Asia Pacific Customer Support Center Email: ap.support@nsc.com National Semiconductor Japan Customer Support Center Fax: 81-3-5639-7507 Email: jpn.feedback@nsc.com Tel: 81-3-5639-7560 www.national.com LM2664 Switched Capacitor Voltage Converter