Analog Devices ADM8828 9 a Datasheet
Switched-Capacitor
a
FEATURES
Inverts Input Supply Voltage
99% Voltage Conversion Efficiency
25 mA Output Current
Shutdown Function
Requires Only Two Capacitors
1 mF Capacitors
18 V Output Resistance
+1.5 V to +5.5 V Input Range
600 mA Quiescent Current
20 nA Shutdown Current (ADM8828)
APPLICATIONS
Handheld Instruments
LCD Panels
Cellular Phones
PDAs
Remote Data Acquisition
Op Amp Power Supplies
Voltage Inverter with Shutdown
ADM8828/ADM8829
FUNCTIONAL BLOCK DIAGRAMS
1
OUT
2
IN
3
CAP–
1
OUT
2
IN
3
CAP–
NC = NO CONNECT
ADM8828
TOP VIEW
(Not to Scale)
ADM8829
TOP VIEW
(Not to Scale)
6
CAP+
5
SHDN
4
GND
6
CAP+
5
NC
4
GND
GENERAL DESCRIPTION
The ADM8828/ADM8829 is a charge-pump voltage inverter
which may be used to generate a negative supply from a positive
input. Input voltages ranging from +1.5 V to +5.5 V can be
inverted into a negative –1.5 V to –5.5 V output supply. This
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 25 mA with
greater than 99% efficiency are achievable.
The ADM8828 also features a low power shutdown (SHDN)
pin. This can be used to disable the device and reduce the quiescent current to 20 nA.
The ADM8828/ADM8829 is available in a 6-lead SOT-23
package.
+1.5V TO +5.5V
INPUT
1mF
CAP+
+
C1
CAP–
GND
ADM8828/
ADM8829
SHDN
OUT
IN
SHUTDOWN
CONTROL
INVERTED
NEGATIVE
OUTPUT
C2
+
1mF
Figure 1. Typical Circuit Configuration
REV. A
Information furnished by Analog Devices is believed to be accurate and
reliable. However, no responsibility is assumed by Analog Devices for its
use, nor for any infringements of patents or other rights of third parties
which may result from its use. No license is granted by implication or
otherwise under any patent or patent rights of Analog Devices.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781/329-4700 World Wide Web Site: http://www.analog.com
Fax: 781/326-8703 © Analog Devices, Inc., 1999
ADM8828/ADM8829–SPECIFICATIONS
(VIN = +5 V, C1, C2 = 1 mF,1 TA = T
wise noted)
MIN
to T
MAX
unless other-
Parameter Min Typ Max Units Test Conditions/Comments
Input Voltage, IN 1.5 5.5 V R
= 10 kΩ
L
Supply Current 600 1000 µA Unloaded
Output Current 25 mA
Output Resistance 18 28 Ω I
Output Ripple 25 mV p-p I
= 5 mA
L
= 5 mA
L
130 mV p-p IL = 25 mA
Charge-Pump Frequency 50 120 190 kHz
65 kHz VIN = +2.25 V
Power Efficiency 90 % R
87 % R
= 200 Ω
L
= 1 kΩ
L
Voltage Conversion Efficiency 99.5 99.96 % No Load
Shutdown Supply Current, I
Shutdown Input Voltage, V
SHDN
SHDN
98 % R
91 % R
0.02 2 µA SHDN = IN
2.0 V SHDN High = Disabled
= 1 kΩ
L
= 200 Ω
L
0.8 V SHDN Low = Enabled
Shutdown Exit Time 175 µsI
NOTES
1
C1 and C2 are low ESR (<0.2 Ω) electrolytic capacitors. High ESR will degrade performance.
Specifications subject to change without notice.
= 5 mA
L
ABSOLUTE MAXIMUM RATINGS*
(T
= +25°C unless otherwise noted)
A
Input Voltage (IN to GND) . . . . . . . . . . . . . . . –0.3 V to +6 V
OUT to GND . . . . . . . . . . . . . . . . . . . . . . . . –6.0 V to +0.3 V
OUT, IN Output Current (Continuous) . . . . . . . . . . . . 50 mA
Output Short Circuit Duration to GND . . . . . . . . . . . 10 secs
Power Dissipation, RT-6 . . . . . . . . . . . . . . . . . . . . . . 570 mW
(Derate 8.3 mW/°C above +70°C)
θ
, Thermal Impedance . . . . . . . . . . . . . . . . . . . . 120°C/W
JA
Operating Temperature Range
Industrial (A Version) . . . . . . . . . . . . . . . . – 40°C to +85°C
Storage Temperature Range . . . . . . . . . . . –65°C to +150°C
Lead Temperature Range (Soldering 10 sec) . . . . . . . . +300°C
Vapor Phase (70 sec) . . . . . . . . . . . . . . . . . . . . . . . . +215°C
Infrared (15 sec) . . . . . . . . . . . . . . . . . . . . . . . . . . . . +220°C
ESD Rating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . >3500 V
*This is a stress rating only and functional operation of the device at these or any
other conditions above those indicated in the operation section of this specification
is not implied. Exposure to absolute maximum rating conditions for extended
periods may affect device reliability.
ORDERING GUIDE
Temperature Branding Package
Model Range Information Option*
ADM8828ART –40°C to +85°C MM0 RT-6
ADM8829ART –40°C to +85°C MN0 RT-6
*RT-6 = 6-lead SOT-23.
PIN FUNCTION DESCRIPTIONS
Mnemonic Function
CAP+ Positive Charge-Pump Capacitor Terminal.
GND Power Supply Ground.
CAP– Negative Charge-Pump Capacitor Terminal.
OUT Output, Negative Voltage.
SHDN Shutdown Control Input. This input, when
high, is used to disable the charge pump
thereby reducing the power consumption.
IN Positive Power Supply Input.
PIN CONFIGURATIONS
1
OUT
2
IN
(Not to Scale)
3
CAP–
1
OUT
IN
2
(Not to Scale)
3
CAP–
NC = NO CONNECT
ADM8828
TOP VIEW
ADM8829
TOP VIEW
6
5
4
6
5
4
CAP+
SHDN
GND
CAP+
NC
GND
–2–
REV. A
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