LM2660/LM2661
Switched Capacitor Voltage Converter

General Description

The LM2660/LM2661 CMOS charge-pump voltage con-
verter inverts a positive voltage in the range of 1.5V to 5.5V
to the corresponding negative voltage. The LM2660/LM2661
uses two low cost capacitors to provide 100 mA of output
current without the cost, size, and EMI related to inductor
based converters. With an operating current of only 120 µA
and operating efficiency greater than 90% at most loads, the
LM2660/LM2661 provides ideal performance for battery
powered systems. The LM2660/LM2661 may also be used
as a positive voltage doubler.

The oscillator frequency can be lowered by adding an exter-
nal capacitor to the OSC pin. Also, the OSC pin may be used
to drive the LM2660/LM2661 with an external clock. For
LM2660, a frequency control (FC) pin selects the oscillator
frequency of 10 kHz or 80 kHz. For LM2661, an external
shutdown (SD) pin replaces the FC pin. The SD pin can be
used to disable the device and reduce the quiescent current
to 0.5 µA. The oscillator frequency for the LM2661 is 80 kHz.

Features

Inverts or doubles input supply voltage

Narrow SO-8 and Mini SO-8 Package

6.5

typical output resistance

88% typical conversion efficiency at 100 mA

(LM2660) selectable oscillator frequency: 10 kHz/80 kHz

(LM2661) low current shutdown mode

Applications

Laptop computers

Cellular phones

Medical instruments

Operational amplifier power supplies

Interface power supplies

Handheld instruments

Basic Application Circuits

Voltage Inverter

DS012911-3

Positive Voltage Doubler

DS012911-4

Splitting V

in Half

DS012911-26

September 1999

LM2660/LM2661

Switched

Capacitor

oltage

Converter

DS012911

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)

(OUT - 0.3V) to (GND + 3V)

FC, OSC

The least negative of (OUT - 0.3V)

or (V+ - 6V) to (V+ + 0.3V)

V+ and OUT Continuous Output Current

120 mA

Output Short-Circuit Duration to GND (Note 2)

1 sec.

Package

Power Dissipation

= 25°C) (Note 3)

735 mW

500 mW

Max (Note 3)

150°C

(Note 3)

170°C/W

250°C/W

Operating Junction
Temperature

Range

-40°C to +85°C

Storage Temperature Range

-65°C to +150°C

Lead Temperature

300°C

(Soldering, 10 seconds)

ESD Rating

2 kV

Electrical Characteristics

Limits in standard typeface are for T

= 25°C, and limits in boldface type apply over the full operating temperature range. Un-

less otherwise specified: V+ = 5V, FC = Open, C

= C

= 150 µF. (Note 4)

Symbol

Parameter

Condition

Min

Typ

Max

Units

V+

Supply Voltage

= 1k

Inverter, LV = Open

3.5

5.5

Inverter, LV = GND

1.5

5.5

Doubler, LV = OUT

2.5

5.5

Supply Current

No Load

FC = Open (LM2660)

0.12

0.5

LV = Open

FC = V+ (LM2660) or

SD = Ground (LM2661)

Shutdown Supply Current

0.5

µA

(LM2661)

Shutdown Pin Input Voltage

Shutdown Mode

2.0

(Note 5)

(LM2661)

Normal Operation

0.3

Output Current

+85°C, OUT

-4V

100

+85°C, OUT

-3.8V

100

OUT

Output Resistance (Note 6)

= 100 mA

+85°C

6.5

+85°C

OSC

Oscillator Frequency (Note 7)

OSC = Open

FC = Open

kHz

FC = V+

Switching Frequency (Note 8)

OSC = Open

FC = Open

2.5

kHz

FC = V+

OSC

OSC Input Current

FC = Open

µA

FC = V+

EFF

Power Efficiency

(1k) between V

and OUT

(500) between GND and OUT

= 100 mA to GND

OEFF

Voltage Conversion Efficiency

No Load

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 device
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

= (T

JMax

- T

, where T

JMax

is the maximum junction temperature, T

is the

ambient temperature, and

is the junction-to-ambient thermal resistance of the specified package.

Note 4: In the test circuit, capacitors C

and C

are 0.2

maximum ESR capacitors. Capacitors with higher ESR will increase output resistance, reduce output

voltage and efficiency.

Note 5: In doubling mode, when V

out

5V, minimum input high for shutdown equals V

out

- 3V.

Note 6: Specified output resistance includes internal switch resistance and capacitor ESR.

Note 7: For LM2661, the oscillator frequency is 80 kHz.

Note 8: The output switches operate at one half of the oscillator frequency, f

OSC

= 2f

LM2660/LM2661

www.national.com

Connection Diagrams

Ordering Information

Order Number

Package Number

Package Marking

Supplied As

LM2660M

M08A

Datecode

Rail (95 units/rail)

LM26

60M

LM2660MX

M08A

Datecode

Tape and Reel (2500 units/rail)

LM26

60M

LM2660MM

MUA08A

S01A (Note 9)

Tape and Reel (250 units/rail)

LM2660MMX

MUA08A

S01A (Note 9)

Tape and Reel (3500 units/rail)

LM2661M

M08A

Datecode

Rail (95 units/rail)

LM26

61M

LM2661MX

M08A

Datecode

Tape and Reel (2500 units/rail)

LM26

61M

LM2661MM

MUA08A

S02A (Note 9)

Tape and Reel (250 units/rail)

LM2661MMX

MUA08A

S02A (Note 9)

Tape and Reel (3500 units/rail)

Note 9: The first letter "S" identifies the part as a switched capacitor converter. The next two numbers are the device number: "01" for a LM2660 device, and "02"
for a LM2661 device. The fourth letter "A" indicates the grade. Only one grade is available. Larger quantity reels are available upon request.

8-Lead SO (M) or Mini SO (MM)

DS012911-1

DS012911-2

Top View

Order Number LM2660M, LM2661M, LM2660MM or LM2661MM

See NS Package Number M08A and MUA08A

LM2660/LM2661

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