LM2766 Switched Capacitor Voltage Converter (Rev. B) parasitic diode from turning-on.A Schottky...

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Transcript of LM2766 Switched Capacitor Voltage Converter (Rev. B) parasitic diode from turning-on.A Schottky...

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    LM2766

    www.ti.com SNVS071B –MARCH 2000–REVISED MAY 2013

    LM2766 Switched Capacitor Voltage Converter Check for Samples: LM2766

    1FEATURES DESCRIPTION The LM2766 CMOS charge-pump voltage converter

    2• Doubles Input Supply Voltage operates as a voltage doubler for an input voltage in

    • SOT-23 6-Pin Package the range of +1.8V to +5.5V. Two low cost capacitors • 20Ω Typical Output Impedance and a diode are used in this circuit to provide up to 20

    mA of output current.• 90% Typical Conversion Efficiency at 20 mA • 0.1µA Typical Shutdown Current The LM2766 operates at 200 kHz switching

    frequency to reduce output resistance and voltage ripple. With an operating current of only 350 µAAPPLICATIONS (operating efficiency greater than 90% with most

    • Cellular Phones loads) and 0.1µA typical shutdown current, the • Pagers LM2766 provides ideal performance for battery

    powered systems. The device is manufactured in a• PDAs SOT-23 6-pin package.• Operational Amplifier Power Supplies

    • Interface Power Supplies • Handheld Instruments

    Basic Application Circuits

    Figure 1. Voltage Doubler

    Connection Diagram

    Figure 2. DBV Package Top View

    Figure 3. Actual Size

    1

    Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.

    2All trademarks are the property of their respective owners.

    PRODUCTION DATA information is current as of publication date. Copyright © 2000–2013, Texas Instruments Incorporated Products conform to specifications per the terms of the Texas Instruments standard warranty. Production processing does not necessarily include testing of all parameters.

    http://www.ti.com/product/lm2766?qgpn=lm2766 http://www.ti.com http://www.ti.com/product/lm2766#samples

  • LM2766

    SNVS071B –MARCH 2000–REVISED MAY 2013 www.ti.com

    Pin Description Pin Name Function

    1 V+ Power supply positive voltage input.

    2 GND Power supply ground input.

    3 CAP− Connect this pin to the negative terminal of the charge-pump capacitor. 4 SD Shutdown control pin, tie this pin to V+ in normal operation.

    5 VOUT Positive voltage output.

    6 CAP+ Connect this pin to the positive terminal of the charge-pump capacitor.

    These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam during storage or handling to prevent electrostatic damage to the MOS gates.

    Absolute Maximum Ratings (1) (2)

    Supply Voltage (V+ to GND, or V+ to VOUT) 5.8V

    SD (GND − 0.3V) to (V+ + 0.3V) VOUT Continuous Output Current 40 mA

    Output Short-Circuit Duration to GND (3) 1 sec.

    Continuous Power Dissipation (TA = 25°C) (4) 600 mW

    TJMax (4) 150°C

    (1) Absolute maximum ratings indicate limits beyond which damage to the device may occur. Electrical specifications do not apply when operating the device beyond its rated operating conditions.

    (2) If Military/Aerospace specified devices are required, please contact the TI Sales Office/ Distributors for availability and specifications. (3) VOUT may be shorted to GND for one second without damage. However, shorting VOUT to V+ may damage the device and should be

    avoided. Also, for temperatures above 85°C, VOUT must not be shorted to GND or V+, or device may be damaged. (4) The maximum allowable power dissipation is calculated by using PDMax = (TJMax − TA)/θJA, where TJMax is the maximum junction

    temperature, TA is the ambient temperature, and θJA is the junction-to-ambient thermal resistance of the specified package.

    Operating Ratings θJA(1) 210°C/W Junction Temperature Range −40° to 100°C Ambient Temperature Range −40° to 85°C Storage Temperature Range −65°C to 150°C Lead Temp. (Soldering, 10 seconds) 240°C

    Human body model 2kV ESD Rating (2)

    Machine model 200V

    (1) The maximum allowable power dissipation is calculated by using PDMax = (TJMax − TA)/θJA, where TJMax is the maximum junction temperature, TA is the ambient temperature, and θJA is the junction-to-ambient thermal resistance of the specified package.

    (2) The human body model is a 100pF capacitor discharged through a 1.5kΩ resistor into each pin. The machine model is a 200pF capacitor discharged directly into each pin.

    2 Submit Documentation Feedback Copyright © 2000–2013, Texas Instruments Incorporated

    Product Folder Links: LM2766

    http://www.ti.com/product/lm2766?qgpn=lm2766 http://www.ti.com http://www.go-dsp.com/forms/techdoc/doc_feedback.htm?litnum=SNVS071B&partnum=LM2766 http://www.ti.com/product/lm2766?qgpn=lm2766

  • LM2766

    www.ti.com SNVS071B –MARCH 2000–REVISED MAY 2013

    Electrical Characteristics Limits in standard typeface are for TJ = 25°C, and limits in boldface type apply over the full operating temperature range. Unless otherwise specified: V+ = 5V, C1 = C2 = 1.0 μF. (1)

    Symbol Parameter Condition Min Typ Max Units

    V+ Supply Voltage 1.8 5.5 V

    IQ Supply Current No Load 350 950 µA

    ISD Shutdown Supply Current 0.1 0.5 µA

    TA = 85°C 0.2

    VSD Shutdown Pin Input Voltage Shutdown Mode 0.6 V

    Normal Operation 2.0

    IL Output Current 2.5V ≤ VIN ≤ 5.5V 20 mA

    1.8V ≤ VIN < 2.5V 10 ROUT Output Resistance

    (2) IL = 20 mA 20 55 Ω fOSC Oscillator Frequency See

    (3) 220 400 700 kHz

    fSW Switching Frequency See (3) 110 200 350 kHz

    PEFF Power Efficiency IL = 20 mA to GND 94 %

    VOEFF Voltage Conversion Efficiency No Load 99.96 %

    (1) In the test circuit, capacitors C1 and C2 are 1.0 µF, 0.3Ω maximum ESR capacitors. Capacitors with higher ESR will increase output resistance, reduce output voltage and efficiency.

    (2) Specified output resistance includes internal switch resistance and capacitor ESR. See the details in the application information for positive voltage doubler.

    (3) The output switches operate at one half of the oscillator frequency, fOSC = 2fSW.

    Test Circuit

    Figure 4. LM2766 Test Circuit

    Copyright © 2000–2013, Texas Instruments Incorporated Submit Documentation Feedback 3

    Product Folder Links: LM2766

    http://www.ti.com/product/lm2766?qgpn=lm2766 http://www.ti.com http://www.go-dsp.com/forms/techdoc/doc_feedback.htm?litnum=SNVS071B&partnum=LM2766 http://www.ti.com/product/lm2766?qgpn=lm2766

  • LM2766

    SNVS071B –MARCH 2000–REVISED MAY 2013 www.ti.com

    Typical Performance Characteristics (Circuit of Figure 4, VIN = 5V, TA = 25°C unless otherwise specified)

    Supply Current vs Output Resistance vs Supply Voltage Capacitance

    Figure 5. Figure 6.

    Output Resistance vs Output Resistance vs Supply Voltage Temperature

    Figure 7. Figure 8.

    Efficiency Output Voltage vs vs

    Load Current Load Current

    Figure 9. Figure 10.

    4 Submit Documentation Feedback Copyright © 2000–2013, Texas Instruments Incorporated

    Product Folder Links: LM2766

    http://www.ti.com/product/lm2766?qgpn=lm2766 http://www.ti.com http://www.go-dsp.com/forms/techdoc/doc_feedback.htm?litnum=SNVS071B&partnum=LM2766 http://www.ti.com/product/lm2766?qgpn=lm2766

  • LM2766

    www.ti.com SNVS071B –MARCH 2000–REVISED MAY 2013

    Typical Performance Characteristics (continued) (Circuit of Figure 4, VIN = 5V, TA = 25°C unless otherwise specified)

    Switching Frequency vs Switching Frequency vs Supply Voltage Temperature

    Figure 11. Figure 12.

    Output Ripple vs Load Current

    Figure 13.

    Copyright © 2000–2013, Texas Instruments Incorporated Submit Documentation Feedback 5

    Product Folder Links: LM2766

    http://www.ti.com/product/lm2766?qgpn=lm2766 http://www.ti.com http://www.go-dsp.com/forms/techdoc/doc_feedback.htm?litnum=SNVS071B&partnum=LM2766 http://www.ti.com/product/lm2766?qgpn=lm2766

  • LM2766

    SNVS071B –MARCH 2000–REVISED MAY 2013 www.ti.com

    CIRCUIT DESCRIPTION

    The LM2766 contains four large CMOS switches which are switched in a sequence to double the input supply voltage. Energy transfer and storage are provided by external capacitors. Figure 14 illustrates the voltage conversion scheme. When S2 and S4 are closed, C1 charges to the supply voltage V+. During this time interval, switches S1 and S3 are open. In the next time interval, S2 and S4 are open; at the same time, S1 and S3 are closed, the sum of the input voltage V+ and the voltage across C1 gives the 2V+ output voltage when there is no load. The output voltage drop when a load is added is determined by the parasitic resistance (Rds(on) of the MOSFET switches and the ESR of the capacitors) and the charge transfer loss between capacitors. Details will be discussed in the following application information section.

    Figure 14. Voltage Doubling Principle

    POSITIVE VOLTAGE DOUBLER

    The main application of the LM2766 is to double the input voltage. 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 2V+. The output resistance Rout is a function of the ON resistance of the internal MOSFET switches, the oscillator frequency, and the capacitance and ESR of C1 and C2. Since the switching curre