MAX1680 Datasheet, PDF (1/12 Pages) Maxim Integrated Products – 125mA, Frequency-Selectable, Switched-Capacitor Voltage Converters

19-1247; Rev 0; 7/97
125mA, Frequency-Selectable,
Switched-Capacitor Voltage Converters
_______________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
3.5Ω) 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.
____________________________Features
o Selectable Switching Frequencies:
125kHz/250kHz (MAX1680)
500kHz/1MHz (MAX1681)
o Allow Use of Small Capacitors
(1µF for the MAX1681)
o 125mA Output Current
o 3.5Ω Output Impedance
o 1µA Logic-Controlled Shutdown
o Configurable as Voltage Inverters or Doublers
o +2.0V to +5.5V Input Voltage Range
o Available in 8-Pin SO Packages
o 90% Efficiency
________________________Applications
Local Negative Supplies
Interface Power Supplies
Op-Amp Power Supplies
MOSFET Bias
______________Ordering Information
PART
MAX1680C/D
MAX1680ESA
MAX1681C/D
MAX1681ESA
TEMP. RANGE
0°C to +70°C
-40°C to +85°C
0°C to +70°C
-40°C to +85°C
*Contact factory for dice specifications.
PIN-PACKAGE
Dice*
8 SO
Dice*
8 SO
Pin Configuration appears at end of data sheet.
__________________________________________________Typical Operating Circuits
FSEL
IN
CAP+ SHDN
+V_INPUT
+3V TO +5.5V
1µF
FSEL
CAP+
IN
C2
1µF
SHDN
DOUBLED
OUTPUT
VOLTAGE
C1
MAX1681
C1
1µF
GND
LV
INVERTED
1µF
+V_INPUT
+4V TO +5.5V
MAX1681
LV
GND
CAP-
OUT
OUTPUT
1µF
C2
VOLTAGE
CAP-
OUT
1µF
INVERTER CONFIGURATION
NOTE: USE 4.7µF CAPACITORS FOR MAX1680
INPUT VOLTAGE RANGE: +2.0V TO +5.5V.
DOUBLER CONFIGURATION
NOTE: USE 4.7µF CAPACITORS FOR MAX1680
INPUT VOLTAGE RANGE: +2.5V TO +5.5V.
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