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ADM8660 데이터시트 PDF




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부품번호 ADM8660 기능
기능 CMOS Switched-Capacitor Voltage Converters
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ADM8660 데이터시트, 핀배열, 회로
CMOS Switched-Capacitor
Voltage Converters
ADM660/ADM8660
FEATURES
ADM660: Inverts or Doubles Input Supply Voltage
ADM8660: Inverts Input Supply Voltage
100 mA Output Current
Shutdown Function (ADM8660)
2.2 F or 10 F Capacitors
0.3 V Drop at 30 mA Load
+1.5 V to +7 V Supply
Low Power CMOS: 600 A Quiescent Current
Selectable Charge Pump Frequency (25 kHz/120 kHz)
Pin Compatible Upgrade for MAX660, MAX665, ICL7660
Available in 16-Lead TSSOP Package
APPLICATIONS
Handheld Instruments
Portable Computers
Remote Data Acquisition
Op Amp Power Supplies
GENERAL DESCRIPTION
The ADM660/ADM8660 is a charge-pump voltage converter
that can be used to either invert the input supply voltage giving
VOUT = –VIN or double it (ADM660 only) giving VOUT = 2 ϫ 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. 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 50 mA with greater than
90% efficiency are achievable, while 100 mA achieves greater
than 80% efficiency.
A Frequency Control (FC) input pin is used to select either
25 kHz or 120 kHz charge-pump operation. This 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. The oscillator frequency
on the ADM660 can also be controlled with an external capacitor
connected to the OSC input or by driving this input 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.
The ADM8660 features a low power shutdown (SD) pin instead
of the external oscillator (OSC) pin. This can be used to disable
the device and reduce the quiescent current to 300 nA.
TYPICAL CIRCUIT CONFIGURATIONS
+1.5V TO +7V
INPUT
C1 +
10F
FC V+
ADM660
CAP+
OSC
GND
LV
CAP–
OUT
C2
+10F
INVERTED
NEGATIVE
OUTPUT
Voltage Inverter Configuration (ADM660)
C1 +
10F
SHUTDOWN
CONTROL
+1.5V TO +7V
INPUT
FC ADM8660
CAP+
GND
V+
LV
CAP–
OUT
SD
C2
+10F
INVERTED
NEGATIVE
OUTPUT
Voltage Inverter Configuration with Shutdown (ADM8660)
The ADM660 is a pin compatible upgrade for the MAX660,
MAX665, ICL7660, and LTC1046.
The ADM660/ADM8660 is available in 8-lead DIP and
narrow-body SOIC. The ADM660 is also available in a 16-lead
TSSOP package.
ADM660/ADM8660 Options
Option
ADM660
ADM8660
Inverting Mode
Doubling Mode
External Oscillator
Shutdown
Package Options
R-8
N-8
RU-16
Y
Y
Y
N
Y
Y
Y
Y
N
N
Y
Y
Y
N
REV. C
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 that
may result from its use. No license is granted by implication or otherwise
under any patent or patent rights of Analog Devices. Trademarks and
registered trademarks are the property of their respective companies.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781/329-4700
www.analog.com
Fax:781/461-3113 ©2011 Analog Devices, Inc. All rights reserved.




ADM8660 pdf, 반도체, 판매, 대치품
ADM660/ADM8660
PIN CONNECTIONS
8-Lead
FC 1
8 V+
CAP+ 2 ADM660 7 OSC
TOP VIEW
GND 3 (Not to Scale) 6 LV
CAP– 4
5 OUT
FC 1
CAP+ 2
GND 3
8
ADM8660 7
TOP VIEW
(Not to Scale) 6
V+
SD
LV
CAP– 4
5 OUT
16-Lead
NC 1
16 NC
NC 2
15 NC
FC 3 ADM660 14 V+
CAP+ 4 TOP VIEW 13 OSC
(Not to Scale)
GND 5
12 LV
CAP– 6
11 OUT
NC 7
10 NC
NC 8
9 NC
NC = NO CONNECT
PIN FUNCTION DESCRIPTIONS
Mnemonic
FC
CAP+
GND
CAP–
OUT
LV
OSC
SD
V+
Inverter Configuration
Function
Frequency Control Input for Internal Oscillator
and Charge Pump. With FC = Open (ADM660)
or connected to GND (ADM8660), fCP = 25 kHz;
with FC = V+, fCP = 120 kHz.
Positive Charge-Pump Capacitor Terminal.
Power Supply Ground.
Negative Charge-Pump Capacitor Terminal.
Output, Negative Voltage.
Low Voltage Operation Input. Connect to GND
when input voltage is less than 3.5 V. Above
3.5 V, LV may be connected to GND or left
unconnected.
ADM660: Oscillator Control Input. OSC is
connected to an internal 15 pF capacitor. An
external capacitor may be connected to slow the
oscillator. An external oscillator may also be
used to overdrive OSC. The charge-pump
frequency is equal to 1/2 the oscillator frequency.
ADM8660: Shutdown Control Input. This in-
put, when high, is used to disable the charge
pump thereby reducing the power consumption.
Positive Power Supply Input.
Doubler Configuration (ADM660 Only)
Mnemonic Function
FC
CAP+
GND
CAP–
OUT
LV
OSC
V+
Frequency Control Input for Internal Oscillator
and Charge Pump. With FC = Open, fCP =
25 kHz; with FC = V+, fCP = 120 kHz.
Positive Charge-Pump Capacitor Terminal.
Positive Input Supply.
Negative Charge-Pump Capacitor Terminal.
Ground.
Low Voltage Operation Input. Connect to OUT.
Must be left unconnected in this mode.
Doubled Positive Output.
–4– REV. C

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ADM8660 전자부품, 판매, 대치품
160
140
120
100
80
LV = GND
60 FC = V+
C1, C2 = 2.2F
40
20
0
–40 –20
0 20 40 60
TEMPERATURE – C
80 100
TPC 13. Charge-Pump Frequency vs. Temperature
ADM660/ADM8660
60
50
40
30 V+ = +1.5V
20
V+ = +3V
10
V+ = +5V
0
–40 –20
0 20 40 60
TEMPERATURE – C
80 100
TPC 14. Output Resistance vs. Temperature
GENERAL INFORMATION
The ADM660/ADM8660 is a switched capacitor voltage con-
verter that can be used to invert the input supply voltage. The
ADM660 can also be used in a voltage doubling mode. The
voltage conversion task is achieved using a switched capacitor
technique using two external charge storage capacitors. An on-
board oscillator and switching network transfers charge between
the charge storage capacitors. The basic principle behind the
voltage conversion scheme is illustrated in Figures 1 and 2.
S1
V+
S2
CAP+ S3
+
C1 S4
CAP–
Φ1 + 2 Φ2
OSCILLATOR
+ OUT = –V+
C2
Figure 1. Voltage Inversion Principle
Switched Capacitor Theory of Operation
As already described, the charge pump on the ADM660/ADM8660
uses a switched capacitor technique in order to invert or double
the input supply voltage. Basic switched capacitor theory is
discussed below.
A switched capacitor building block is illustrated in Figure 3.
With the switch in position A, capacitor C1 will charge to voltage
V1. The total charge stored on C1 is q1 = C1V1. The switch is
then flipped to position B discharging C1 to voltage V2. The
charge remaining on C1 is q2 = C1V2. The charge transferred
to the output V2 is, therefore, the difference between q1 and
q2, so q = q1–q2 = C1 (V1–V2).
A
V1
B
C1
V2
C2 RL
S1
V+
S2
CAP+ S3
+
C1 S4
CAP–
Φ1 + 2 Φ2
OSCILLATOR
+ VOUT = 2V+
C2
V+
Figure 3. Switched Capacitor Building Block
As the switch is toggled between A and B at a frequency f, the
charge transfer per unit time or current is:
I = f (q) = f (C1)(V1 – V 2)
Therefore,
Figure 2. Voltage Doubling Principle
Figure 1 shows the voltage inverting configuration, while Figure 2
shows the configuration for voltage doubling. An oscillator
generating antiphase signals φ1 and φ2 controls switches S1, S2,
and S3, S4. During φ1, switches S1 and S2 are closed charging
C1 up to the voltage at V+. During φ2, S1 and S2 open and S3
and S4 close. With the voltage inverter configuration during φ2,
the positive terminal of C1 is connected to GND via S3 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 trans-
ferred 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. The reason for this is explained in the
following section. For maximum efficiency, capacitors with low
ESR are, therefore, recommended.
I = (V1 – V 2)/(1 / fC1) = (V1 – V 2)/(REQ )
where REQ = 1/fC1
The switched capacitor may, therefore, be replaced by an equivalent
resistance whose value is dependent on both the capacitor size
and the switching frequency. This explains why lower capacitor
values may be used with higher switching frequencies. It should
be remembered that as the switching frequency is increased the
power consumption will increase due to some charge being lost
at each switching cycle. As a result, at high frequencies, the power
efficiency starts decreasing. Other losses include the resistance
of the internal switches and the equivalent series resistance (ESR)
of the charge storage capacitors.
REQ
V1
REQ = 1/fC1
V2
C2 RL
The voltage doubling configuration reverses some of the con-
nections, but the same principle applies.
Figure 4. Switched Capacitor Equivalent Circuit
REV. C
–7–

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ADM8660

CMOS Switched-Capacitor Voltage Converters

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