ADM8829ARTZ-REEL7 [ADI]
Switched Capacitor Voltage Inverter;
| 型号： | ADM8829ARTZ-REEL7 |
| 厂家： | 
ADI |
| 描述： | Switched Capacitor Voltage Inverter 光电二极管 |
| 文件： | 总6页 (文件大小：73K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
Switched-Capacitor
Voltage Inverter with Shutdown
a
ADM8828/ADM8829
FUNCTIONAL BLOCK DIAGRAMS
FEATURES
Inverts Input Supply Voltage
99% Voltage Conversion Efficiency
25 mA Output Current
Shutdown Function
Requires Only Two Capacitors
1 F Capacitors
1
2
3
6
5
4
CAP+
SHDN
GND
OUT
IN
ADM8828
TOP VIEW
(Not to Scale)
CAP–
18 ⍀ Output Resistance
+1.5 V to +5.5 V Input Range
600 A Quiescent Current
20 nA Shutdown Current (ADM8828)
1
2
3
6
5
4
CAP+
NC
OUT
IN
ADM8829
TOP VIEW
(Not to Scale)
CAP–
GND
NC = NO CONNECT
APPLICATIONS
Handheld Instruments
LCD Panels
Cellular Phones
PDAs
Remote Data Acquisition
Op Amp Power Supplies
GENERAL DESCRIPTION
+1.5V TO +5.5V
INPUT
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.
CAP+
IN
+
ADM8828/
ADM8829
C1
1F
SHUTDOWN
CONTROL
SHDN
CAP–
INVERTED
OUT
GND
NEGATIVE
OUTPUT
C2
+ 1F
The ADM8828 also features a low power shutdown (SHDN)
pin. This can be used to disable the device and reduce the quies-
cent current to 20 nA.
Figure 1. Typical Circuit Configuration
The ADM8828/ADM8829 is available in a 6-lead SOT-23
package.
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
otherwiseunderanypatentorpatentrightsofAnalogDevices.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781/329-4700
Fax: 781/326-8703
World Wide Web Site: http://www.analog.com
© Analog Devices, Inc., 1999
(VIN = +5 V, C1, C2 = 1 F,1 TA = TMIN to TMAX unless other-
wise noted)
ADM8828/ADM8829–SPECIFICATIONS
Parameter
Min
Typ
Max
Units
V
Test Conditions/Comments
RL = 10 kΩ
Input Voltage, IN
Supply Current
1.5
5.5
600
1000
µA
Unloaded
Output Current
Output Resistance
Output Ripple
25
mA
Ω
mV p-p
mV p-p
18
25
130
28
IL = 5 mA
IL = 5 mA
IL = 25 mA
Charge-Pump Frequency
50
65
120
190
kHz
kHz
VIN = +2.25 V
Power Efficiency
90
87
99.96
98
91
%
%
%
%
%
RL = 200 Ω
RL = 1 kΩ
No Load
RL = 1 kΩ
RL = 200 Ω
Voltage Conversion Efficiency
99.5
2.0
Shutdown Supply Current, ISHDN
Shutdown Input Voltage, VSHDN
0.02
175
2
µA
V
V
SHDN = IN
SHDN High = Disabled
SHDN Low = Enabled
IL = 5 mA
0.8
Shutdown Exit Time
µs
NOTES
1C1 and C2 are low ESR (<0.2 Ω) electrolytic capacitors. High ESR will degrade performance.
Specifications subject to change without notice.
PIN FUNCTION DESCRIPTIONS
Function
ABSOLUTE MAXIMUM RATINGS*
(TA = +25°C unless otherwise noted)
Mnemonic
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)
CAP+
GND
CAP–
OUT
Positive Charge-Pump Capacitor Terminal.
Power Supply Ground.
Negative Charge-Pump Capacitor Terminal.
Output, Negative Voltage.
SHDN
Shutdown Control Input. This input, when
high, is used to disable the charge pump
thereby reducing the power consumption.
θJA, Thermal Impedance . . . . . . . . . . . . . . . . . . . . 120°C/W
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
IN
Positive Power Supply Input.
PIN CONFIGURATIONS
*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.
1
2
3
6
5
4
CAP+
SHDN
GND
OUT
IN
ADM8828
TOP VIEW
(Not to Scale)
CAP–
ORDERING GUIDE
1
2
3
6
5
4
Temperature
Range
Branding
Information Option*
Package
CAP+
NC
OUT
IN
ADM8829
TOP VIEW
(Not to Scale)
Model
CAP–
GND
ADM8828ART –40°C to +85°C
ADM8829ART –40°C to +85°C
MM0
MN0
RT-6
RT-6
NC = NO CONNECT
*RT-6 = 6-lead SOT-23.
–2–
REV. A
Typical Performance Characteristics–
ADM8828/ADM8829
60
0.8
0.7
0.6
0.5
0.4
0.3
0.2
I
= 5mA
L
50
OUTPUT VOLTAGE RIPPLE
@ V = 4.75V
IN
40
30
20
10
0
OUTPUT VOLTAGE RIPPLE
@ V = 1.9V
IN
OUTPUT VOLTAGE RIPPLE
@ V = 3.15V
IN
0.1
0
0.47
1
2.2
3.3
1
1.5
2
2.5
3
3.5
4
4.5
5
5.5
CAPACITANCE – F
SUPPLY VOLTAGE – V
Figure 2. Power Supply Current vs. Voltage
Figure 5. Output Voltage Ripple vs. Capacitance
35
30
25
20
15
10
350
300
OUTPUT VOLTAGE RIPPLE
@ V = 4.75V, V
= –4.0V
IN
OUT
250
200
150
OUTPUT VOLTAGE RIPPLE
@ V = 3.15V, V = –2.5V
IN
OUT
100
50
0
5
0
OUTPUT VOLTAGE RIPPLE
@ V = 1.9V, V = –1.5V
IN
OUT
1.5
2
2.5
3
3.5
4
4.5
5
5.5
0.47
1
2.2
3.3
SUPPLY VOLTAGE – V
CAPACITANCE – F
Figure 3. Output Source Resistance vs. Supply Voltage
Figure 6. Output Voltage Ripple vs. Capacitance
0
20
18
–0.5
OUTPUT CURRENT @ V = 4.75V
IN
OUTPUT VOLTAGE @ V = 2.0V
IN
16
14
12
10
8
–1
–1.5
–2
OUTPUT CURRENT @ V = 3.15V
IN
OUTPUT VOLTAGE @ V = 3.3V
IN
–2.5
–3
OUTPUT CURRENT @ V = 1.9V
6
IN
–3.5
–4
4
2
0
OUTPUT VOLTAGE @ V = 5.0V
IN
–4.5
–5
0
0.47
1
2.2
3.3
5
10
15
20
25
30
35
40
45
CAPACITANCE – F
OUTPUT CURRENT – mA
Figure 4. Output Current vs. Capacitance
Figure 7. Output Voltage vs. Output Current
REV. A
–3–
ADM8828/ADM8829
100
90
80
70
60
200
180
160
140
120
100
80
P
@ V = 5.0V
IN
EFF
PUMP FREQUENCY
@ V = 3.3V
IN
P
@ V = 3.3V
IN
EFF
PUMP FREQUENCY
@ V = 5.0V
IN
P
@ V = 2.0V
IN
EFF
50
40
30
20
PUMP FREQUENCY
@ V = 1.5V
IN
60
40
10
0
20
0
0
5
10
15
20
I
25
– mA
30
35
40
45
50
–50 –30 –10
10
25
40
60
80
90
110 125
TEMPERATURE – ؇C
OUT
Figure 8. Power Efficiency vs. Output Current
Figure 10. Charge Pump Frequency vs. Temperature
50
45
RESISTANCE (⍀) @ V = 1.5V
IN
40
35
30
25
20
15
10
RESISTANCE (⍀) @ V = 3.3V
IN
RESISTANCE (⍀) @ V = 5.0V
IN
5
0
–50 –30 –10 10
25
40
60
80
90 110 125
TEMPERATURE – ؇C
Figure 9. Output Resistance vs. Temperature
–4–
REV. A
ADM8828/ADM8829
GENERAL INFORMATION
Capacitor Selection
The ADM8828/ADM8829 is a switched capacitor voltage con-
verter that can be used to invert the input supply voltage.
The flying capacitor C1 can be increased to reduce the output
resistance.
The voltage conversion task is achieved using a switched capaci-
tor technique using two external charge storage capacitors. An
on-chip oscillator and switching network transfers charge between
the charge storage capacitors. The basic principle behind the
voltage conversion scheme is illustrated below.
The output capacitor size C2 affects the output ripple. Increas-
ing the capacitor size reduces the peak-peak ripple. The ESR
affects both the output impedance and the output ripple.
Reducing the ESR reduces the output impedance and ripple.
For convenience it is recommended that both C1 and C2 be the
same value.
CAP+
+
S1
S2
S3
S4
V+
The ac impedance of the ADM8828/ADM8829 may be reduced
by using a bypass capacitor on the input supply. This capacitor
should be connected between the input supply and GND. It will
provide instantaneous current surges as required. Suitable capaci-
tors of 1 µF or greater may be used.
C1
OUT = –V+
+
CAP–
C2
⌽1
⌽2
، 2
OSCILLATOR
Figure 11. Voltage Inversion Principle
+1.5V TO +5.5V
INPUT
An oscillator generating antiphase signals φ1 and φ2 controls
switches S1, S2 and S3, S4. During φ1, switches S1 and S2 are
closed while S3 and S4 are open, thereby charging C1 up to the
voltage at V+. During φ2, S1 and S2 open and S3 and S4 close.
The positive terminal of C1 is connected to GND via S3 during
this phase and the negative terminal of C1 connects to VOUT
via S4. The net result is voltage inversion at VOUT wrt GND.
Charge on C1 is transferred to C2 during φ2. Capacitor C2
maintains this voltage during φ1. The charge transfer efficiency
depends on the on-resistance of the switches, the frequency at
which they are being switched and also on the equivalent series
resistance (ESR) of the external capacitors. For maximum effi-
ciency, capacitors with low ESR are, therefore, recommended.
CAP+
IN
+
ADM8828/
ADM8829
C1
1F
SHUTDOWN
CONTROL
SHDN
CAP–
INVERTED
OUT
GND
NEGATIVE
OUTPUT
C2
+ 1F
Figure 12. Typical Circuit Configuration
Shutdown Input
The ADM8828 contains a shutdown input that can be used to
disable the device and hence reduce the power consumption. A
logic high level on the SHDN input shuts the device down
reducing the quiescent current to 0.02 µA. During shutdown
the output voltage discharges to 0 V. Therefore, ground ref-
erenced loads are not powered during this state. When exiting
shutdown, it takes several cycles (approximately 175 µs) for the
charge pump to reach its final value. If the shutdown function is
not being used, SHDN should be hardwired to GND.
REV. A
–5–
ADM8828/ADM8829
OUTLINE DIMENSIONS
Dimensions shown in inches and (mm).
6-Lead SOT-23
(RT-6)
0.122 (3.10)
0.106 (2.70)
6
1
5
2
4
3
0.071 (1.80)
0.059 (1.50)
0.118 (3.00)
0.098 (2.50)
PIN 1
0.037 (0.95) BSC
0.075 (1.90)
BSC
0.051 (1.30)
0.035 (0.90)
0.057 (1.45)
0.035 (0.90)
10؇
0؇
0.020 (0.50)
0.010 (0.25)
0.022 (0.55)
0.014 (0.35)
0.006 (0.15)
0.000 (0.00)
SEATING
PLANE
0.009 (0.23)
0.003 (0.08)
–6–
REV. A
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ADI
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