Äîêóìåíòàöèÿ è îïèñàíèÿ www.docs.chipfind.ru

LM2665
Switched Capacitor Voltage Converter

General Description

The LM2665 CMOS charge-pump voltage converter oper-
ates as a voltage doubler for an input voltage in the range of
+2.5V to +5.5V. Two low cost capacitors and a diode
(needed during start-up) are used in this circuit to provide up
to 40 mA of output current. The LM2665 can also work as a
voltage divider to split a voltage in the range of +1.8V to
+11V in half.

The LM2665 operates at 160 kHz oscillator frequency to re-
duce output resistance and voltage ripple. With an operating
current of only 650 µA (operating efficiency greater than 90%
with most loads) and 1µA typical shutdown current, the
LM2665 provides ideal performance for battery powered
systems. The device is in SOT-23-6 package.

Features

Doubles or Splits Input Supply Voltage

SOT23-6 Package

Typical Output Impedance

90% Typical Conversion Efficiency at 40 mA

1µA Typical Shutdown Current

Applications

Cellular Phones

Pagers

PDAs

Operational Amplifier Power Suppliers

Interface Power Suppliers

Handheld Instruments

Basic Application Circuits

Voltage Doubler

DS100049-1

Splitting V

in Half

DS100049-2

November 1999

LM2665

Switched

Capacitor

oltage

Converter

DS100049

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

(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

= 25°C)(Note 3)

600 mW

JMax

(Note 3)

150°C

(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

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

less otherwise specified: V+ = 5V, C

= C

= 3.3 µF. (Note 4)

Symbol

Parameter

Condition

Min

Typ

Max

Units

V+

Supply Voltage

2.5

5.5

Supply Current

No Load

650

1250

µA

Shutdown Supply Current

µA

Shutdown Pin Input Voltage

Shutdown Mode

2.0

(Note 5)

Normal Operation

0.8

(Note 6)

Output Current

Sum of the R

ds(on)

of the four

internal MOSFET switches

= 40 mA

3.5

OUT

Output Resistance (Note 7)

= 40 mA

OSC

Oscillator Frequency

(Note 8)

160

kHz

Switching Frequency

(Note 8)

kHz

EFF

Power Efficiency

(1.0k) between GND and

OUT

= 40 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 tem-
peratures 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 3.3 µF, 0.3

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

voltage and efficiency.

Note 5: The minimum input high for the shutdown pin equals 40% of V+.

Note 6: The maximum input low of the shutdown pin equals 20% of V+.

Note 7: Specified output resistance includes internal switch resistance and capacitor ESR. See the details in the application information for positive voltage doubler.

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

OSC

= 2f

LM2665

www.national.com

Connection Diagram

Ordering Information

Order Number

Package

Number

Package

Marking

Supplied as

LM2665M6

MA06A

SO4A (Note 9)

Tape and Reel (1000 units/rail)

LM2665M6X

MA06A

SO4A (Note 9)

Tape and Reel (3000 units/rail)

Note 9: The first letter

identifies the part as a switched capacitor converter. The next two numbers are the device number. The fourth letter

indicates the

grade. Only one grade is available. Larger quantity reels are available upon request.

Pin Description

Pin

Name

Function

Voltage Doubler

Voltage Split

V+

Power supply positive voltage input.

Positive voltage output.

GND

Power supply ground input

Same as doubler

CAP-

Connect this pin to the negative terminal of the
charge-pump capacitor

Same as doubler.

Shutdown control pin, tie this pin to ground in normal
operation.

Same as doubler.

OUT

Positive voltage output.

Power supply positive voltage
input

CAP+

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

Same as doubler

Circuit Description

The LM2665 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 capaci-
tors. Figure 2 illustrates the voltage conversion scheme.
When S

and S

are closed, C

charges to the supply volt-

age V+. During this time interval, switches S

and S

are

open. In the next time interval, S

and S

are open; at the

same time, S

and S

are closed, the sum of the input volt-

age V+ and the voltage across C

gives the 2V+ output volt-

age when there is no load. The output voltage drop when a
load is added is determined by the parasitic resistance (R

s(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.

Application Information

Positive Voltage Doubler

The main application of the LM2665 is to double the input
voltage. The range of the input supply voltage is 2.5V to
5.5V.

The output characteristics of this circuit can be approximated
by an ideal voltage source in series with a resistance. The

6-Lead SOT (M6)

DS100049-13

Top View With Package Marking

DS100049-22

Actual Size

DS100049-14

FIGURE 2. Voltage Doubling Principle

LM2665

Ð­Ð»ÐµÐºÑ‚Ñ€Ð¾Ð½Ð½Ñ‹Ð¹ ÐºÐ¾Ð¼Ð¿Ð¾Ð½ÐµÐ½Ñ‚: LM2665M6X

ÐÐ»ÐµÐºÑ‚Ñ€Ð¾Ð½Ð½Ñ‹Ð¹ ÐºÐ¾Ð¼Ð¿Ð¾Ð½ÐµÐ½Ñ‚: LM2665M6X