ADMOS AMS682ES, AMS682EP, AMS682CS, AMS682CP Datasheet

Advanced AMS682
Monolithic INVERTING VOLTAGE DOUBLER
Systems

FEATURES APPLICATIONS

•• 99.9% Voltage Conversion Efficiency •• Portable Handheld Instrumentation

•• 92% Power Conversion Efficiency •• Cellular Phones

•• Wide Input Voltage Range +2.4V to 5.5V •• Panel Meters

•• 185µµA Supply Current •• -10V from +5V logic Supply

•• Available in SO-8 and PDIP Packages •• -6V from a Single 3V Lithium Cell

•• Only 3 external Capacitors Required •• LCD Display Bias Generator

•• Operational Amplifiers Power Supplies

GENERAL DESCRIPTION

The AMS682 is a CMOS charge pump converter that provides an inverted doubled output from a single positive supply.
Requiring only three external capacitors for full circuit implementation the device has an on -board 12kHz (typical) oscillator
which provides the clock.
Low output source impedance (typically 140Ω), provides output current up to 10mA. The AMS682 features low quiescent
current and high efficiency, making it the ideal choice for a wide variety of applications that require a negative voltage
derived from a single positive supply. The compact size and minimum external parts count of the AMS682 makes it useful in
many medium current, dual voltage analog power supplies.

The AMS682E is operational in the full industrial temperature range of -40°C to 85°C while AMS682C is operating over a
0°C to 70°C temperature range. The AMS682E/AMS682C are available in surface mount 8-Pin SOIC (SO-8) and 8-Pin
Plastic DIP (PDIP) packages.

ORDERING INFORMATION:

PACKAGE TYPE OPERATING

8 LEAD SOIC 8 LEAD PDIP

AMS682ES AMS682EP
AMS682CS AMS682CP

TEMPERATURE RANGE

-40 to 85° C
0 to 70° C

TYPICAL OPERATING CIRCUIT PIN CONFIGURATIONS

+2.4V < V

V

IN

C

1

C

2

GND

All Caps = 3.3µF

< +5.5V

IN

V

IN

+

C

+

-

+

-

ON/OFF

1

-

C

1

+

C

2

-

V

OUT

C

2

GND

C

+

V

OUT

OUT

= -(2 X VIN)

V

OUT

8-LEAD DIP/ 8-LEAD SOIC

-

C

1

2

+

2

C

2

-

C

2

V

OUT

3

4

AMS682

8

7

C

6

5

ON/OFF

+

1

V

IN

GND

Advanced Monolithic Systems, Inc. 6680B Sierra Lane, Dublin, CA 94568 Phone [phone] Fax [phone]

AMS682

2

+

ABSOLUTE MAXIMUM RATINGS

V

IN

VIN ∆V/∆T 1V/µsec
V

OUT

V

Short Circuit Duration Continuous Storage temperature

OUT

Power Dissipation (TA  70°C)
Plastic DIP 730mW Lead Temperature (Soldering 10sec)
SOIC 470mW

+5.8V Operating Temperature Range

AMS682E

-11.6V AMS682C

Soldering information

-40°C to 85°C
0°C to 70°C

-85°C to +150°C

+300°C

ELECTRICAL CHARACTERISTICS

Electrical Characteristics at VIN =+5V and TA = +25°C test circuit figure 1, unless otherwise specified.

Parameter

Supply Voltage Range

Supply Current

V

IN

I

IN

Conditions

RL=2kΩ

RL = ∞
RL = ∞

V

Source Resistance

OUT

Source Resistance

Oscillator Frequency F
Power Efficiency P
Voltage Conversion Efficiency V

R

OUT

OSC

EFF

OUTEFF

I

I

-

I

= 5mA , V

L

RL = 2kΩ

V

­L =

-

=10mA

L

OUT RL

10mA

IN

= ∞

= 2.8V

PIN DESCRIPTION

PIN NO
8-PIN DIP/SOIC SYMBOL DESCRIPTION

1 C

2 C

3 C

4 V

5 GND Input. Device ground.
6 V
7 C

8 ON/OFF ON/OFF Oscilator.

-

1

-

2

OUT

IN

+

1

Input. Capacitor C1 negative
terminal.
Input. Capacitor C2 positive
terminal.
Input. Capacitor C2 negative
terminal
Output. Negative output voltage
(-2VIN)

Input. Power supply voltage.
Input. Capacitor C1 positive
terminal.

AMS682

Min Typ Max

2.4









90 92
99 99.9



185



140
170

12

Units

5.5 V

300

400

180

230

320





V

IN

(+5V)

GND

6

V

7 8

IN

+

C

ON/OFF

+

1

C

1

1

-

-

C

1

2

+

C

+

2

C

2

3

V-

-

-

OUT

C

2

GND
5

All Caps = 3.3µF

-

4

­C

OUT

+

V

OUT

R

L

Figure 1. AMS682 Test Circuit

µA

Ω

kHz

%
%

Advanced Monolithic Systems, Inc. 6680B Sierra Lane, Dublin, CA 94568 Phone [phone] Fax [phone]

AMS682

1

+

2

+

2

3

­OUT

DETAILED DESCRIPTION

Phase 1

VSS charge storage- before this phase of the clock cycle,

capacitor C1 is already charged to +5V. C
to ground and the charge in C
Since C

is at +5V, the voltage potential across capacitor C

-

is transferred to C

1

is now -10V.

VIN =+5V

SW1

+

C1 C2

-

+

­ SW2

SW3

SW4

-5V

Figure 2. Charge Pump - Phase 1

Phase 2

is then switched

-

.

2

V

OUT

­C

3

+

EFFICIENCY CONSIDERATIONS

Theoretically a charge pump voltage multiplier can approach
100% efficiency under the following conditions:

• The charge pump switches have virtually no offset and are

extremely low on resistance.

• Minimal power is consumed by the drive circuitry.

• The Impedances of the reservoir and pump capacitors are

negligible.

For the AMS682, efficiency is as shown below:

Voltage Efficiency = V
V
V

Power Loss = I

There will be a substantial voltage difference between V
2VIN if the impedances of the pump capacitors C1 and C2 are
high with respect to their respective output loads.
If the values of the reservoir capacitor C3 are larger the output
ripple will be reduced. The efficiency will be improved if both
pump and reservoir capacitors have larger values. ( See
“Capacitor Selection” in Application Section.)

/ (-2VIN )

OUT

= -2VIN + V

OUT
DROP

(V

OUT

= (I

DROP

OUT

)

) (R

DROP

OUT

)

and

OUT

VSS transfer- phase two of the clock connects the negative
terminal of C2 to the negative side of reservoir capacitor C
and the positive terminal of C2 to the ground, transferring the
generated -10V to C3. Simultaneously, the positive side of
capacitor C1 is switched to +5V and the negative side is
connected to ground. C2 is then switched to VCC and GND and
Phase 1 begins again.

VIN =+5V

SW1

+

C1 C2

-

+

­ SW2

SW4

-10V

SW3

V

­C

+

OUT

3

Figure 3. Charge Pump - Phase 2

MAXIMUM OPERATING LIMITS

The AMS682 has on-chip zener diodes that clamp VIN to
approximately 5.8V, and V
maximum supply voltage will potentially damage the chip.
With an input voltage of 2V to 5.5V the AMS682 will operate
over the entire operating temperature range.

to -11.6V. Exceeding the

APPLICATIONS

Negative Doubling Converter

The AMS682 is most commonly used as a charge pump voltage
converter which provides a negative output of two times a
positive input voltage (Fig.4)

+

22µF

C

1

+

C

2

22µF

1

C

C

3

C

4

V-

-

1

+

2

-

2

OUT

ON/OFF

V

GND

8
72

+

C

1

C

3

22µF

V

GND

V

IN

-

6

IN

5

+

Figure 4. Inverting Voltage Doubler

OUT

Advanced Monolithic Systems, Inc. 6680B Sierra Lane, Dublin, CA 94568 Phone [phone] Fax [phone]