CMOS Switched-Capacitor
Voltage Converters
a
ADM660/ADM8660
FEATURES
TYP ICAL CIRCUIT CO NFIGURATIO NS
ADM660: Inverts or Doubles Input Supply Voltage
ADM8660: Inverts Input Supply Voltage
100 m A Output Current
+1.5V TO +7V
INPUT
Shutdow n Function (ADM8660)
2.2 F or 10 F Capacitors
0.3 V Drop at 30 m A Load
+1.5 V to +7 V Supply
Low Pow er CMOS: 600 A Quiescent Current
Selectable Charge Pum p Frequency (25 kHz/ 120 kHz)
Pin Com patible Upgrade for MAX660, MAX665, ICL7660
Available in 16-Lead TSSOP Package
V+
OSC
LV
FC
ADM660
CAP+
GND
CAP–
C1
10µF
INVERTED
NEGATIVE
OUTPUT
OUT
C2
10µF
APPLICATIONS
Voltage Inverter Configuration (ADM660)
Handheld Instrum ents
Portable Com puters
Rem ote Data Acquisition
Op Am p Pow er Supplies
+1.5V TO +7V
INPUT
FC
V+
ADM8660
CAP+
GND
GENERAL D ESCRIP TIO N
T he ADM660/ADM8660 is a charge-pump voltage converter
that can be used to either invert the input supply voltage giving
LV
C1
10µF
INVERTED
NEGATIVE
OUTPUT
OUT
CAP–
SD
C2
10µF
SHUTDOWN
CONTROL
VOUT = –VIN or double it (ADM660 only) giving VOUT = 2 × VIN
.
Input voltages ranging from +1.5 V to +7 V can be inverted into
a negative –1.5 V to –7 V output supply. T his inverting scheme
is ideal for generating a negative rail in single power supply
systems. Only two small external capacitors are needed for the
charge pump. Output currents up to 50 mA with greater than
90% efficiency are achievable, while 100 mA achieves greater
than 80% efficiency.
Voltage Inverter Configuration with Shutdown (ADM8660)
T he ADM660 is a pin compatible upgrade for the MAX660,
MAX665, ICL7660 and LT C1046.
T he ADM660/ADM8660 is available in 8-pin DIP and narrow-
body SOIC. T he ADM660 is also available in a 16-lead T SSOP
package.
A Frequency Control (FC) input pin is used to select either
25 kHz or 120 kHz charge-pump operation. T his is used to
optimize capacitor size and quiescent current. With 25 kHz
selected, a 10 µF external capacitor is suitable, while with
120 kHz the capacitor may be reduced to 2.2 µF. T he oscillator
frequency on the ADM660 can also be controlled with an exter-
nal capacitor connected to the OSC input or by driving this in-
put with an external clock. In applications where a higher supply
voltage is desired it is possible to use the ADM660 to double
the input voltage. With input voltages from 2.5 V to 7 V, output
voltages from 5 V to 14 V are achievable with up to 100 mA
output current.
AD M660/AD M8660 O ptions
O ption
AD M660
AD M8660
Inverting Mode
Doubling Mode
External Oscillator
Shutdown
Y
Y
Y
N
Y
N
N
Y
Package Options
SO-8
N-8
Y
Y
Y
Y
Y
N
T he ADM8660 features a low power shutdown (SD) pin in-
stead of the external oscillator (OSC) pin. T his can be used to
disable the device and reduce the quiescent current to 300 nA.
RU-16
REV. A
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use, nor for any infringem ents of patents or other rights of third parties
which m ay result from its use. No license is granted by im plication or
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© Analog Devices, Inc., 1997