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Rainbow Electronics MAX1681 User Manual

General description, Applications, Features

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_______________General Description

The MAX1680/MAX1681 inductorless switched-capaci-
tor voltage converters either invert an input voltage of
+2.0V to +5.5V or double it while supplying up to
125mA output current. They have a selectable-frequen-
cy option that allows the use of small capacitors: 4.7µF
(MAX1680), 1µF (MAX1681). With their high output cur-
rent capability, these charge-pump devices are suit-
able replacements for inductor-based regulators, which
require more expensive external components and addi-
tional board space.

The devices’ equivalent output resistance (typically
3.5

) allows them to deliver as much as 125mA with

only a 440mV drop. A shutdown feature reduces quies-
cent current to less than 1µA. The MAX1680/MAX1681
are available in 8-pin SO packages. For devices that
deliver up to 50mA in smaller µMAX packages, refer to
the MAX860/MAX861 data sheet.

________________________Applications

Local Negative Supplies

Interface Power Supplies

Op-Amp Power Supplies

MOSFET Bias

____________________________Features

Selectable Switching Frequencies:

125kHz/250kHz (MAX1680)
500kHz/1MHz (MAX1681)

Allow Use of Small Capacitors
(1µF for the MAX1681)

125mA Output Current

3.5

Output Impedance

1µA Logic-Controlled Shutdown

Configurable as Voltage Inverters or Doublers

+2.0V to +5.5V Input Voltage Range

Available in 8-Pin SO Packages

90% Efficiency

MAX1680/MAX1681

125mA, Frequency-Selectable,

Switched-Capacitor Voltage Converters

________________________________________________________________

Maxim Integrated Products

1

MAX1681

FSEL

IN

CAP+

SHDN

GND

C1

1

µ

F

+V

INPUT

+3V TO +5.5V

INVERTED
OUTPUT
VOLTAGE

C2

1

µ

F

1

µ

F

LV

CAP-

INVERTER CONFIGURATION

OUT

MAX1681

FSEL

IN

CAP+

SHDN

GND

C1

1

µ

F

C2

1

µ

F

DOUBLED
OUTPUT
VOLTAGE

+V

INPUT

+4V TO +5.5V

NOTE: USE 4.7

µ

F CAPACITORS FOR MAX1680

INPUT VOLTAGE RANGE: +2.5V TO +5.5V.

NOTE: USE 4.7

µ

F CAPACITORS FOR MAX1680

INPUT VOLTAGE RANGE: +2.0V TO +5.5V.

1

µ

F

LV

CAP-

DOUBLER CONFIGURATION

OUT

__________________________________________________Typical Operating Circuits

19-1247; Rev 0; 7/97

PART

MAX1680

C/D

MAX1680ESA

MAX1681

C/D

0°C to +70°C

-40°C to +85°C

0°C to +70°C

TEMP. RANGE

PIN-PACKAGE

Dice*

8 SO

Dice*

______________Ordering Information

*

Contact factory for dice specifications.

Pin Configuration appears at end of data sheet.

MAX1681ESA

-40°C to +85°C

8 SO

For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800.
For small orders, phone 408-737-7600 ext. 3468.