LM2682
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SNVS044B –NOVEMBER 1999–REVISED MAY 2013
LM2682 Switched Capacitor Voltage Doubling Inverter
Check for Samples: LM2682
1FEATURES DESCRIPTION
The LM2682 is a CMOS charge-pump voltage
2• Inverts Then Doubles Input Supply Voltage inverter capable of converting positive voltage in the
• Small VSSOP Package and SOIC Package range of +2.0V to +5.5V to the corresponding
• 90ΩTypical Output Impedance doubled negative voltage of −4.0V to −11.0V
respectively. The LM2682 uses three low cost
• 94% Typical Power Efficiency at 10 mA capacitors to provide 10 mA of output current without
the cost, size, and EMI related to inductor based
APPLICATIONS circuits. With an operating current of only 150 μA and
• LCD Contrast Biasing an operating efficiency greater than 90% with most
loads, the LM2682 provides ideal performance for
• GaAs Power Amplifier Biasing battery powered systems. The LM2682 offers a
• Interface Power Supplies switching frequency of 6 kHz.
• Handheld Instrumentation
• Laptop Computers and PDAs
Typical Operating Circuit and Pin Configuration 8-Pin VSSOP
or 8-Pin SOIC
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.
1Please 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 © 1999–2013, 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.
LM2682
SNVS044B –NOVEMBER 1999–REVISED MAY 2013
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Absolute Maximum Ratings(1)
Input Voltage (VIN) +5.8V
VIN dV/dT 1V/μsec
VOUT −11.6V
VOUT Short-Circuit Duration Continuous
Storage Temperature −65°C to +150°C
Lead Temperature Soldering +300°C
VSSOP 300 mW
Power Dissipation(2) SOIC 470 mW
TJMAX +150°C
(1) Absolute Maximum Ratings are those values beyond which damage to the device may occur. Operating Ratings indicate conditions for
which the device is intended to be functional, but do not ensure specific performance limits. For ensured specifications and test
conditions, see the Electrical Characteristics.
(2) The maximum power dissipation must be de-rated at elevated temperatures (only needed for TA>85°C) and is limited by TJMAX
(maximum junction temperature), θJ-A (junction to ambient thermal resistance) and TA(ambient temperature). θJ-A is 140°C/W for the
SOIC-8 package and 220°C/W for the VSSOP-8 package. The maximum power dissipation at any temperature is:PDissMAX = (TJMAX −
TA)/θJ-A up to the value listed in the Absolute Maximum Ratings.
Operating Ratings Human Body Model 2 kV
ESD Susceptibility(1) Machine Model 200V
Ambient Temp. Range −40°C to +85°C
Junction Temp. Range −40°C to +125°C
(1) The human body model is a 100 pF capacitor discharged through a 1.5 kΩresistor into each pin. The machine model is a 200pF
capacitor discharged directly into each pin.
LM2682
Electrical Characteristics
VIN = 5V and C1= C2= C3= 3.3μF unless otherwise specified. Limits with bold typeface apply over the full operating ambient
temperature range, −40°C to +85°C, limits with standard typeface apply for TA= 25°C.
Symbol Parameter Conditions Min Typical(1) Max Units
VIN Supply Voltage Range RL= 2 kΩ2.0 5.5 V
IIN Supply Current Open Circuit, No Load 150 300 μA
400
ROUT VOUT Source Resistance IL= 10 mA 90 150 Ω
200
IL=5 mA, VIN=2 V 110 250 Ω
fOSC Oscillator Frequency See(2) 12 30 kHz
fSW Switching Frequency See(2) 615 kHz
ηPOWER Power Efficiency RL= 2k(3) 90 93 %
ηVOLTAGE Voltage Conversion Efficiency 99.9 %
(1) Typical numbers are at 25°C and represent the most likely norm.
(2) The output switches operate at one half of the oscillator frequency, fOSC = 2fSW.
(3) The minimum specification is specified by design and is not tested.
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SNVS044B –NOVEMBER 1999–REVISED MAY 2013
Table 1. PIN DESCRIPTIONS
Pin Number Symbol Description
1 C1−Capacitor C1negative terminal
2 C2+ Capacitor C2positive terminal
3 C2−Capacitor C2negative terminal
4 VOUT Negative output voltage (−2VIN)
5 GND Device ground
6 VIN Power supply voltage
7 C1+ Capacitor C1positive terminal
8 NC No Connection
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SNVS044B –NOVEMBER 1999–REVISED MAY 2013
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Typical Performance Characteristics
VIN = 5V and TA= 25°C unless otherwise noted.
Output Resistance Output Voltage
vs vs
Input Voltage Load Current
Figure 1. Figure 2.
Supply Current Output Resistance
vs vs
Input Voltage Temperature
Figure 3. Figure 4.
Output Voltage Ripple
vs
Load Current
Figure 5.
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SNVS044B –NOVEMBER 1999–REVISED MAY 2013
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APPLICATION INFORMATION
VOLTAGE DOUBLING INVERTER
The main application of the LM2682 is to generate a negative voltage that is twice the positive input voltage. This
circuit requires only three external capacitors and is connected as shown in Figure 6. It is important to keep in
mind that the efficiency of the circuit is determined by the output resistance. A derivation of the output resistance
is shown below:
ROUT = 2(RSW1+RSW2+ESRC1+RSW3+RSW4+ESRC2) +2(RSW1+RSW2+ESRC1+RSW3+RSW4+ESRC2) + 1/(fOSC×C1) +
1/(fOSC×C2) + ESRC3
Using the assumption that all four switches have the same ON resistance our equation becomes:
ROUT = 16RSW + 4ESRC1 + 4ESRC2 + ESRC3 + 1/(fOSC×C1) + 1/(fOSC×C2)
Output resistance is typically 90Ωwith an input voltage of +5V, an operating temperature of 25°C, and using low
ESR 3.3 μF capacitors. This equation shows the importance of capacitor selection. Large value, low ESR
capacitors will reduce the output resistance significantly but will also require a larger overall circuit. Smaller
capacitors will take up less space but can lower efficiency greatly if the ESR is large. Also to be considered is
that C1 must be rated at 6 VDC or greater while C2 and C3 must be rated at 12 VDC or greater.
The amount of output voltage ripple is determined by the output capacitor C3 and the output current as shown in
this equation:
VRIPPLE P-P = IOUT × (2×ESRC3 + 1/[2×(fOSC×C3)])
Once again a larger capacitor with smaller ESR will give better results.
+5V TO −5V REGULATED VOLTAGE CONVERTER
Another application in which the LM2682 can be used is for generating a −5V regulated supply from a +5V
unregulated supply. This involves using an op-amp and a reference and is connected as shown in Figure 7. The
LM358 op-amp was chosen for its low cost and versatility and the LM4040-5.0 reference was chosen for its low
bias current requirement. Of course other combinations may be used at the designer's discretion to fit accuracy,
efficiency, and cost requirements. With this configuration the circuit is well regulated and is still capable of
providing nearly 10 mA of output current. With a 9 mA load the circuit can typically maintain 5% regulation on the
output voltage with the input varying anywhere from 4.5V to the maximum of 5.5V. With less load the results are
even better. Voltage ripple concerns are reduced in this case since the ripple at the output of the LM2682 is
reduced at the output by the PSRR of the op-amp used.
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SNVS044B –NOVEMBER 1999–REVISED MAY 2013
PARALLELING DEVICES
Any number of devices can be paralleled to reduce the output resistance. As shown in Figure 8, each device
must have its own pumping capacitors, C1 and C2, but only one shared output capacitor is required. The
effective output resistance is the output resistance of one device divided by the number of devices used in
parallel. Paralleling devices also gives the capability of increasing the maximum output current. The maximum
output current now becomes the maximum output current for one device multiplied by the number of devices
used in parallel. For example, if you parallel two devices you can get 20 mA of output current and have half the
output resistance of one device supplying 10 mA.
Figure 8. Paralleling Devices
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SNVS044B –NOVEMBER 1999–REVISED MAY 2013
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REVISION HISTORY
Changes from Revision A (May 2013) to Revision B Page
• Changed layout of National Data Sheet to TI format ............................................................................................................ 7
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PACKAGE OPTION ADDENDUM
www.ti.com 21-Oct-2014
Addendum-Page 1
PACKAGING INFORMATION
Orderable Device Status
(1)
Package Type Package
Drawing Pins Package
Qty Eco Plan
(2)
Lead/Ball Finish
(6)
MSL Peak Temp
(3)
Op Temp (°C) Device Marking
(4/5)
Samples
LM2682MM/NOPB ACTIVE VSSOP DGK 8 1000 Green (RoHS
& no Sb/Br) CU SN Level-1-260C-UNLIM -40 to 85 S11A
LM2682MMX/NOPB ACTIVE VSSOP DGK 8 3500 Green (RoHS
& no Sb/Br) CU SN Level-1-260C-UNLIM -40 to 85 S11A
(1) The marketing status values are defined as follows:
ACTIVE: Product device recommended for new designs.
LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect.
NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design.
PREVIEW: Device has been announced but is not in production. Samples may or may not be available.
OBSOLETE: TI has discontinued the production of the device.
(2) Eco Plan - The planned eco-friendly classification: Pb-Free (RoHS), Pb-Free (RoHS Exempt), or Green (RoHS & no Sb/Br) - please check http://www.ti.com/productcontent for the latest availability
information and additional product content details.
TBD: The Pb-Free/Green conversion plan has not been defined.
Pb-Free (RoHS): TI's terms "Lead-Free" or "Pb-Free" mean semiconductor products that are compatible with the current RoHS requirements for all 6 substances, including the requirement that
lead not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, TI Pb-Free products are suitable for use in specified lead-free processes.
Pb-Free (RoHS Exempt): This component has a RoHS exemption for either 1) lead-based flip-chip solder bumps used between the die and package, or 2) lead-based die adhesive used between
the die and leadframe. The component is otherwise considered Pb-Free (RoHS compatible) as defined above.
Green (RoHS & no Sb/Br): TI defines "Green" to mean Pb-Free (RoHS compatible), and free of Bromine (Br) and Antimony (Sb) based flame retardants (Br or Sb do not exceed 0.1% by weight
in homogeneous material)
(3) MSL, Peak Temp. - The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature.
(4) There may be additional marking, which relates to the logo, the lot trace code information, or the environmental category on the device.
(5) Multiple Device Markings will be inside parentheses. Only one Device Marking contained in parentheses and separated by a "~" will appear on a device. If a line is indented then it is a continuation
of the previous line and the two combined represent the entire Device Marking for that device.
(6) Lead/Ball Finish - Orderable Devices may have multiple material finish options. Finish options are separated by a vertical ruled line. Lead/Ball Finish values may wrap to two lines if the finish
value exceeds the maximum column width.
Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided. TI bases its knowledge and belief on information
provided by third parties, and makes no representation or warranty as to the accuracy of such information. Efforts are underway to better integrate information from third parties. TI has taken and
continues to take reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on incoming materials and chemicals.
TI and TI suppliers consider certain information to be proprietary, and thus CAS numbers and other limited information may not be available for release.
PACKAGE OPTION ADDENDUM
www.ti.com 21-Oct-2014
Addendum-Page 2
In no event shall TI's liability arising out of such information exceed the total purchase price of the TI part(s) at issue in this document sold by TI to Customer on an annual basis.
TAPE AND REEL INFORMATION
*All dimensions are nominal
Device Package
Type Package
Drawing Pins SPQ Reel
Diameter
(mm)
Reel
Width
W1 (mm)
A0
(mm) B0
(mm) K0
(mm) P1
(mm) W
(mm) Pin1
Quadrant
LM2682MM/NOPB VSSOP DGK 8 1000 178.0 12.4 5.3 3.4 1.4 8.0 12.0 Q1
LM2682MMX/NOPB VSSOP DGK 8 3500 330.0 12.4 5.3 3.4 1.4 8.0 12.0 Q1
PACKAGE MATERIALS INFORMATION
www.ti.com 23-Sep-2013
Pack Materials-Page 1
*All dimensions are nominal
Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm)
LM2682MM/NOPB VSSOP DGK 8 1000 210.0 185.0 35.0
LM2682MMX/NOPB VSSOP DGK 8 3500 367.0 367.0 35.0
PACKAGE MATERIALS INFORMATION
www.ti.com 23-Sep-2013
Pack Materials-Page 2
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