LTC1144
Switched-Capacitor
Wide Input Range
Voltage Converter
with Shutdown
Features
Description
Wide Operating Supply Voltage Range: 2V to 18V
Boost Pin (Pin 1) for Higher Switching Frequency
Simple Conversion of 15V to –15V Supply
Low Output Resistance: 120Ω Maximum
Power Shutdown to 8µA with SHDN Pin
Open Circuit Voltage Conversion Efficiency:
99.9% Typical
n Power Conversion Efficiency: 93% Typical
n Easy to Use
The LTC®1144 is a monolithic CMOS switched-capacitor
voltage converter. It performs supply voltage conversion
from positive to negative from an input range of 2V to
18V, resulting in complementary output voltages of –2V to
–18V. Only two noncritical external capacitors are needed
for the charge pump and charge reservoir functions.
n
n
n
n
n
n
Applications
n
n
n
n
n
n
n
Conversion of 15V to ±15V Supplies
Inexpensive Negative Supplies
Data Acquisition Systems
High Voltage Upgrade to LTC1044 or 7660
Voltage Division and Multiplications
Automotive Applications
Battery Systems with Wall Adapter/Charger
The converter has an internal oscillator that can be
overdriven by an external clock or slowed down when
connected to a capacitor. The oscillator runs at a 10kHz
frequency when unloaded. A higher frequency outside the
audio band can also be obtained if the Boost Pin is tied to
V+. The SHDN pin reduces supply current to 8µA and can
be used to save power when the converter is not in use.
The LTC1144 contains an internal oscillator, divide-by- two,
voltage level shifter, and four power MOSFETs. A special
logic circuit will prevent the power N-channel switch
substrate from turning on.
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear
Technology Corporation. All other trademarks are the property of their respective owners.
Typical Application
Output Voltage vs Load Current, V+ = 15V
Generating –15V from 15V
LTC1144
2
3
4
CAP+
–15
V+
OSC
GND
SHDN
CAP–
VOUT
8
ROUT = 56Ω
TA = 25°C
15V INPUT
7
–14
6
5
–15V OUTPUT
10µF
1144 TA01
OUTPUT VOLTAGE (V)
10µF
+
BOOST
+
1
–13
–12
–11
–10
0
10
30
40
20
LOAD CURRENT (mA)
50
1144 TA02
1144fa
For more information www.linear.com/LTC1144
1
LTC1144
Absolute Maximum Ratings
(Note 1)
Supply Voltage (V+) (Transient) ................................20V
Supply Voltage (V+) (Operating) ............................... 18V
Input Voltage on Pins 1, 6, 7
(Note 2) ............................. –0.3V < VIN < (V+) + 0.3V
Output Short-Circuit Duration
V+ ≤ 10V ..................................................... Indefinite
V+ ≤ 15V .......................................................... 30 sec
V+ ≤ 20V .............................................. Not Protected
Power Dissipation.............................................. 500mW
Operating Temperature Range
LTC1144C................................................. 0°C to 70°C
LTC1144I...............................................–40°C to 85°C
Storage Temperature Range................... –65°C to 150°C
Lead Temperature (Soldering, 10 sec).................... 300°C
Pin Configuration
TOP VIEW
TOP VIEW
BOOST 1
+
8
V+
BOOST 1
8
V+
CAP+ 2
7
OSC
2
7
OSC
GND 3
6
SHDN
GND 3
6
SHDN
CAP– 4
5
VOUT
CAP– 4
5
VOUT
CAP
N8 PACKAGE
8-LEAD PLASTIC DIP
TJMAX = 110°C, θJA = 100°C/W
S8 PACKAGE
8-LEAD PLASTIC SOIC
TJMAX = 110°C, θJA = 130°C/W
Order Information
LEAD FREE FINISH
TAPE AND REEL
PART MARKING
PACKAGE DESCRIPTION
TEMPERATURE RANGE
LTC1144CN8#PBF
LTC1144CN8#TRPBF
LTC1144CN8
8-Lead Plastic DIP
0°C to 70°C
LTC1144IN8#PBF
LTC1144IN8#TRPBF
LTC1144IN8
8-Lead Plastic DIP
–40°C to 85°C
LTC1144CS8#PBF
LTC1144CS8#TRPBF
1144
8-Lead Plastic SOIC
0°C to 70°C
LTC1144IS8#PBF
LTC1144IS8#TRPBF
1144I
8-Lead Plastic SOIC
–40°C to 85°C
Consult LTC Marketing for parts specified with wider operating temperature ranges.
Consult LTC Marketing for information on nonstandard lead based finish parts.
For more information on lead free part marking, go to: http://www.linear.com/leadfree/
For more information on tape and reel specifications, go to: http://www.linear.com/tapeandreel/
1144fa
2
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LTC1144
Electrical Characteristics
The l denotes the specifications which apply over the full operating
temperature range,V+ = 15V, COSC = 0pF, Test Circuit Figure 1, otherwise specifications are at TA = 25°C.
LTC1144C
SYMBOL
IS
PARAMETER
CONDITIONS
Supply Voltage Range
RL = 10k
Supply Current
RL = ∞, Pins 1, 6 No Connection,
l
fOSC = 10kHz
l
SHDN = 0V, RL = ∞, Pins 1, 7
No Connection
V+ = 5V, RL = ∞, Pins 1, 6
No Connection, fOSC = 4kHz
V+ = 5V, SHDN = 0V, RL = ∞,
Pins 1, 7 No Connection
ROUT
Output Resistance
MIN
TYP
2
0.008
l
l
2
0.03
0.008
MAX
UNITS
18
V
1.1
1.6
mA
mA
0.035
mA
0.10
0.15
mA
mA
0.002
0.015
0.002
0.018
mA
56
100
120
56
100
140
Ω
Ω
90
250
90
300
Ω
l
Oscillator Frequency
V+ = 15V (Note 3)
V+ = 5V
Power Efficiency
RL = 2k at 10kHz
l
90
93
Voltage Conversion Efficiency
RL = ∞
l
97.0
99.9
Oscillator Sink or Source Current
V+ = 5V (VOSC = 0V to 5V)
V+ = 15V (VOSC = 0V to 15V)
Note 1: Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2: Connecting any input terminal to voltages greater than V+ or less
than ground may cause destructive latch-up. It is recommended that no
inputs from sources operating from external supplies be applied prior to
power-up of the LTC1144.
18
TYP
0.10
0.13
l
l
fOSC
MIN
1.1
1.3
V+ = 15V, IL = 20mA at 10kHz
V+ = 5V, IL = 3mA at 4kHz
LTC1144I
MAX
10
4
0.5
4
10
4
kHz
kHz
90
93
%
97.0
99.9
%
0.5
4
µA
µA
Note 3: fOSC is tested with COSC = 100pF to minimize the effects of test
fixture capacitance loading. The 0pF frequency is correlated to this 100pF
test point, and is intended to simulate the capacitance at pin 7 when the
device is plugged into a test socket and no external capacitor is used.
1144fa
For more information www.linear.com/LTC1144
3
LTC1144
Typical Performance Characteristics
Output Resistance
vs Supply Voltage
300
Output Resistance vs
Temperature
200
150
100
V + = 5V
IL = 3mA
100
80
60
V + = 15V
IL = 20mA
40
50
6
10 12 14
8
SUPPLY VOLTAGE (V)
16
20
–55 –25
18
50
25
75
0
TEMPERATURE (°C)
Oscillator Frequency as a
Function of COSC
OSCILLATOR FREQUENCY (kHz)
OSCILLATOR FREQUENCY (kHz)
1000
100
BOOST = V +
10
1
BOOST = OPEN OR GROUND
0.1
BOOST = OPEN OR GROUND
1
–55 –25
0
25
50
75
TEMPERATURE (°C)
5
10
15
20
LOAD CURRENT (mA)
OUTPUT VOLTAGE (V)
SUPPLY CURRENT (µA)
25
30
LTC1144 • TPC07
16
18
TA = 25°C
V+ = 15V
C1 = C2 = 10µF
BOOST = OPEN
–5
–10
–15
125
0
10
20
30
40
LOAD CURRENT (mA)
LTC1144 • TPC06
100
100
1000
V + = 15V
100
V + = 5V
10
1
10
0.1
OSCILLATOR FREQUENCY (kHz)
60
Power Conversion Efficiency and
Supply Current vs Load Current
TA = 25°C
C1 = C2 = 10µF
1
0.01
50
100
LTC1144 • TPC08
PEFF
80
80
IS
60
60
40
40
20
0
0
TA = 25°C
V+ = 15V
20
C1 = C2 = 10µF
BOOST = OPEN
(SEE TEST CIRCUIT)
0
10
30
40
50
20
LOAD CURRENT (mA)
SUPPLY CURRENT (mA)
0
8
10 12
14
SUPPLY VOLTAGE (V)
LTC1144 • TPC05
10000
ROUT = 90Ω
–5
100
Supply Current as a Function of
Oscillator Frequency
–4
6
ROUT = 56Ω
Output Voltage vs Load Current
–3
4
Output Voltage vs Load Current
BOOST = V +
LTC1144 • TPC04
–2
2
LTC1144 • TPC03
TA = 25°C
V + = 15V
10
100
10
1000
1
10000
EXTERNAL CAPACITANCE (PIN 7 TO GND), COSC (pF)
–1
1
0
100
0.01
TA = 25°C
V+ = 5V
C1 = C2 = 10µF
BOOST = OPEN
BOOST = OPEN OR GROUND
10
Oscillator Frequency
vs Temperature
TA = 25°C
V + = 15V
0
BOOST = V +
LTC1144 • TPC02
LTC1144 • TPC01
1000
TA = 25°C
COSC = 0
100
125
100
OUTPUT VOLTAGE (V)
4
POWER CONVERSION EFFICIENCY (%)
2
OSCILLATOR FREQUENCY (kHz)
120
OUTPUT RESISTANCE (Ω)
OUTPUT RESISTANCE (Ω)
1000
140
TA = 25°C
250
0
Oscillator Frequency
vs Supply Voltage
LTC1144 • TPC09
1144fa
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For more information www.linear.com/LTC1144
LTC1144
Typical Performance Characteristics
Power Conversion Efficiency
vs Oscillator Frequency
30
60
IS
20
4
20
TA = 25°C
V + = 5V
C1 = C2 = 10µF
BOOST = OPEN
(SEE TEST CIRCUIT)
12
16
8
LOAD CURRENT (mA)
20
10
95
100µF
10µF
90
85
IL = 3mA
1µF
80
75
0.1
–1
1µF
0.1µF
0.1µF
10µF
500
1µF
1µF
100µF
IL = 20mA
1
10
OSCILLATOR FREQUENCY (kHz)
0
0.1
100
1
10
OSCILLATOR FREQUENCY (kHz)
Output Voltage vs Load Current
0
V + = 5V
TA = 25°C
C1 = C2
BOOST = 5V
BOOST = OPEN
–2
0.1µF 10µF
0.1µF
–3
1µF
1µF
10µF
–5
V + = 15V
TA = 25°C
C1 = C2
BOOST = 15V
BOOST = OPEN
0.1µF
–10
0.1µF
–4
10µF
0
0.01
0.1
1
10
LOAD CURRENT (mA)
100
–5
0.001
0.01
0.1
1
10
LOAD CURRENT (mA)
100
–15
0.001
LTC1144 • G14
LTC1144 • TPC13
100
LTC1144 • TPC12
Output Voltage vs Load Current
0
V + = 5V
OUTPUT VOLTAGE (V)
RIPPLE VOLTAGE (mV)
1000
10µF
LTC1144 • TPC11
Ripple Voltage vs Load Current
TA = 25°C
C1 = C2
BOOST = 5V
BOOST =
OPEN
TA = 25°C
V + = 15V
1000
1µF
LTC1144 • TPC10
1500
3000
2000
10µF
70
0
TA = 25°C, V + = 15V
BOOST = OPEN
100µF
OUTPUT VOLTAGE (V)
40
0
POWER CONVERSION EFFICIENCY (%)
40
SUPPLY CURRENT (mA)
POWER CONVERSION EFFICIENCY (%)
PEFF
80
0
100
50
100
Output Resistance
vs Oscillator Frequency
OUTPUT RESISTANCE (Ω)
Power Conversion Efficiency and
Supply Current vs Load Current
1µF
1µF
10µF
10µF
0.01
10
0.1
1
LOAD CURRENT (mA)
100
LTC1144 • TPC15
Pin Functions
Boost (Pin 1): This pin will raise the oscillator frequency
by a factor of 10 if tied high.
CAP+ (Pin 2): Positive Terminal for Pump Capacitor.
SHDN (Pin 6): Shutdown Pin. Tie to V+ pin or leave floating for normal operation. Tie to ground when in shutdown
mode.
CAP– (Pin 4): Negative Terminal for Pump Capacitor.
OSC (Pin 7): Oscillator Input Pin. This pin can be overdriven
with an external clock or can be slowed down by connecting an external capacitor between this pin and ground.
VOUT (Pin 5): Output of the Converter.
V+ (Pin 8): Input Voltage.
GND (Pin 3): Ground Reference.
1144fa
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5
LTC1144
Test Circuit
V+
15V
1
2
C1 +
3
10µF
IS
8
EXTERNAL
OSCILLATOR R
L
7
LTC1144
4
6
IL
5
COSC
C2
10µF
VOUT
+
1144 F01
Figure 1.
Applications Information
Theory of Operation
To understand the theory of operation of the LTC1144,
a review of a basic switched-capacitor building block is
helpful.
In Figure 2, when the switch is in the left position, capacitor C1 will charge to voltage V1. The total charge on C1
will be q1 = C1V1. The switch then moves to the right,
discharging C1 to voltage V2. After this discharge time,
the charge on C1 is q2 = C1V2. Note that charge has been
transferred from the source V1 to the output V2. The
amount of charge transferred is:
REQUIV = 1/(f × C1). Thus, the equivalent circuit for the
switched-capacitor network is as shown in Figure 3.
Examination of Figure 4 shows that the LTC1144 has the
same switching action as the basic switched-capacitor
building block. With the addition of finite switch onresistance and output voltage ripple, the simple theory,
although not exact, provides an intuitive feel for how the
device works.
For example, if you examine power conversion efficiency
as a function of frequency (see Figure 5), this simple
∆q = q1 – q2 = C1(V1 – V2)
V1
V1
REQUIV
C2
V2
1
REQUIV =
f × C1
f
RL
C1
V2
C2
RL
1144 F03
Figure 3. Switched-Capacitor Equivalent Circuit
1144 F02
Figure 2. Switched-Capacitor Building Block
If the switch is cycled f times per second, the charge
transfer per unit time (i.e., current) is:
Rewriting in terms of voltage and impedance equivalence,
BOOST
V1− V2 V1− V2
=
1 REQUIV
f ×C1
SW1
φ
10X
(1)
I = f × ∆q = f × C1(V1 – V2)
I=
V+
(8)
÷2
OSC
OSC
(7)
φ
CAP +
(2)
C1
SW2
+
CAP –
(4)
VOUT
(5)
+
GND
(3)
SHDN
(6)
A new variable REQUIV has been defined such that
C2
1144 F04
Figure 4. LTC1144 Switched-Capacitor
Voltage Converter Block Diagram
1144fa
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LTC1144
Applications Information
theory will explain how the LTC1144 behaves. The loss,
and hence the efficiency, is set by the output impedance.
As frequency is decreased, the output impedance will
eventually be dominated by the 1/(f × C1) term and power
efficiency will drop.
V+
9I
BOOST
(1)
Note also that power efficiency decreases as frequency
goes up. This is caused by internal switching losses which
occur due to some finite charge being lost on each switching
cycle. This charge loss per unit cycle, when multiplied by
the switching frequency, becomes a current loss. At high
frequency this loss becomes significant and the power
efficiency starts to decrease.
90
400
85
300
80
200
OUTPUT
RESISTANCE
75
70
0.1
GND
(3)
500
POWER
CONVERSION
EFFICIENCY
1144 F06
V+
REQUIRED FOR
TTL LOGIC
NC
C1
+
1
8
2
7
3
LTC1144
4
6
5
100
1
10
OSCILLATOR FREQUENCY (kHz)
≈20pF
I
Figure 6. Oscillator
OUTPUT RESISTANCE (Ω)
POWER CONVERSION EFFICIENCY (%)
95
9I
600
V + = 15V, C1 = C2 = 10µF
IL = 20mA, TA = 25°C
SCHMITT
TRIGGER
OSC
(7)
100k
OSC INPUT
–(V
+
100
I
0
100
+)
C2
1144 F07
Figure 7. External Clocking
1144 F05
Figure 5. Power Conversion Efficiency and Output
Resistance vs Oscillator Frequency
SHDN (Pin 6)
The LTC1144 has a SHDN pin that will disable the internal
oscillator when it is pulled low. The supply current will
also drop to 8µA.
OSC (Pin 7) and Boost (Pin 1)
The switching frequency can be raised, lowered or driven
from an external source. Figure 6 shows a functional
diagram of the oscillator circuit.
By connecting the boost pin (pin 1) to V+, the charge and
discharge current is increased, and hence the frequency
is increased by approximately 10 times. Increasing the
frequency will decrease output impedance and ripple for
higher load currents.
Loading pin 7 with more capacitance will lower the
frequency. Using the boost (pin 1) in conjunction with
external capacitance on pin 7 allows user selection of the
frequency over a wide range.
Driving the LTC1144 from an external frequency source
can be easily achieved by driving pin 7 and leaving the
boost pin open as shown in Figure 7. The output current
from pin 7 is small, typically 4µA, so a logic gate is capable
of driving this current. The choice of using a CMOS logic
gate is best because it can operate over a wide supply
voltage range (3V to 15V) and has enough voltage swing
to drive the internal Schmitt trigger shown in Figure 6. For
5V applications, a TTL logic gate can be used by simply
adding an external pull-up resistor (see Figure 7).
Capacitor Selection
External capacitors C1 and C2 are not critical. Matching is
not required, nor do they have to be high quality or tight
tolerance. Aluminum or tantalum electrolytics are excellent
choices, with cost and size being the only consideration.
1144fa
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7
LTC1144
Typical Applications
Negative Voltage Converter
V IN
2V TO 18V
Figure 8 shows a typical connection which will provide
a negative supply from an available positive supply. This
circuit operates over full temperature and power supply
ranges without the need of any external diodes.
The output voltage (pin 5) characteristics of the circuit
are those of a nearly ideal voltage source in series with a
56Ω resistor. The 56Ω output impedance is composed of
two terms: 1) the equivalent switched capacitor resistance
(see Theory of Operation), and 2) a term related to the
on-resistance of the MOS switches.
V+
2V TO 18V
1
3
2
7
3
4
Vd
1N4148
+
5
4
+
10µF
VOUT = 2(VIN – 1)
+
10µF
1144 F09
Figure 9. Voltage Doubler
Ultra-Precision Voltage Divider
An ultra-precision voltage divider is shown in Figure 10. To
achieve the 0.002% accuracy indicated, the load current
should be kept below 100nA. However, with a slight loss
in accuracy, the load current can be increased.
6
1
VOUT = –V +
10µF
C1
10µF
1144 F08
At an oscillator frequency of 10kHz and C1 = 10µF, the
first term is:
1
1
=
= 20Ω
3
(fOSC / 2) ×C1 5×10 ×10 ×10−6
Notice that the above equation for REQUIV is not a capacitive reactance equation (XC = 1/ωC) and does not contain
a 2π term.
The exact expression for output impedance is extremely
complex, but the dominant effect of the capacitor is clearly
shown in Figure 5. For C1 = C2 = 10µF, the output impedance goes from 56Ω at fOSC = 10kHz to 250Ω at fOSC =
1kHz. As the 1/(f × C) term becomes large compared to
the switch on-resistance term, the output resistance is
determined by 1/(f × C) only.
8
2
+
3
7
LTC1144
6
4
V+ ±0.002%
2
TMIN ≤ TA ≤ TMAX
IL ≤ 100nA
Figure 8. Negative Voltage Converter
6
V+
4V TO 36V
5
TMIN ≤ TA ≤ TMAX
REQUIV =
LTC1144
Vd +
1N4148
7
LTC1144
+
10µF
8
8
2
+
1
+
5
C2
10µF
1144 F10
Figure 10. Ultra-Precision Voltage Divider
Battery Splitter
A common need in many systems is to obtain (+) and
(–) supplies from a single battery or single power supply
system. Where current requirements are small, the circuit shown in Figure 11 is a simple solution. It provides
symmetrical ± output voltages, both equal to one half the
input voltage. The output voltages are both referenced to
pin 3 (output common).
VB
18V
+
C1
10µF
+
1
8
2
7
3
4
LTC1144
VB /2
9V
6
5
–VB /2
–9V
Voltage Doubling
+
Figure 9 shows a two-diode capacitive voltage doubler.
With a 15V input, the output is 29.45V with no load and
28.18V with a 10mA load.
C2
10µF
OUTPUT
COMMON
1144 F11
Figure 11. Battery Splitter
1144fa
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LTC1144
Package Description
Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings.
N Package
8-Lead PDIP (Narrow .300 Inch)
(Reference LTC DWG # 05-08-1510 Rev I)
.400*
(10.160)
MAX
8
7
6
5
1
2
3
4
.255 ±.015*
(6.477 ±0.381)
.300 – .325
(7.620 – 8.255)
.008 – .015
(0.203 – 0.381)
(
+.035
.325 –.015
8.255
+0.889
–0.381
)
.045 – .065
(1.143 – 1.651)
.065
(1.651)
TYP
.100
(2.54)
BSC
.130 ±.005
(3.302 ±0.127)
.120
(3.048) .020
MIN
(0.508)
MIN
.018 ±.003
N8 REV I 0711
(0.457 ±0.076)
NOTE:
1. DIMENSIONS ARE
INCHES
MILLIMETERS
*THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS.
MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED .010 INCH (0.254mm)
1144fa
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9
LTC1144
Package Description
Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings.
S8 Package
8-Lead Plastic Small Outline (Narrow .150 Inch)
(Reference LTC DWG # 05-08-1610 Rev G)
.189 – .197
(4.801 – 5.004)
NOTE 3
.045 ±.005
.050 BSC
8
.245
MIN
.160 ±.005
.010 – .020
× 45°
(0.254 – 0.508)
2
.053 – .069
(1.346 – 1.752)
0°– 8° TYP
.016 – .050
(0.406 – 1.270)
5
.150 – .157
(3.810 – 3.988)
NOTE 3
1
RECOMMENDED SOLDER PAD LAYOUT
.008 – .010
(0.203 – 0.254)
6
.228 – .244
(5.791 – 6.197)
.030 ±.005
TYP
NOTE:
1. DIMENSIONS IN
7
.014 – .019
(0.355 – 0.483)
TYP
INCHES
(MILLIMETERS)
2. DRAWING NOT TO SCALE
3. THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS.
MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED .006" (0.15mm)
4. PIN 1 CAN BE BEVEL EDGE OR A DIMPLE
3
4
.004 – .010
(0.101 – 0.254)
.050
(1.270)
BSC
SO8 REV G 0212
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LTC1144
Revision History
REV
DATE
DESCRIPTION
A
04/14
Change 0.0002% to 0.002% under the Ultra-Precision Voltage Divider section.
PAGE NUMBER
8
1144fa
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However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection
of its circuits
as described
herein will not infringe on existing patent rights.
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information
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11
LTC1144
Typical Application
Regulated –5V Output Voltage
9V
1
Figure 12 shows a regulated –5V output with a 9V input.
With a 0mA to 5mA load current, the ROUT is below 20Ω.
1µF
8
2
+
3
7
LTC1144
6
4
Paralleling for Lower Output Resistance
Additional flexibility of the LTC1144 is shown in Figure 13.
Two LTC1144s are connected in parallel to provide a lower
effective output resistance. However, if the output resistance is dominated by 1/(f × C1), increasing the capacitor
size (C1) or increasing the frequency will be of more benefit
than the paralleling circuit shown.
2N2369
5
36k
300k
– 5V
100µF
+
1144 F12
Figure 12. A Regulated –5V Supply
V+
8
1
C1
10µF
+
7
2
3
LTC1144
6
5
4
8
1
C1
10µF
+
7
2
3
LTC1144
6
5
4
VOUT = –(V +)
+
1/4 CD4077*
C2
20µF
* THE EXCLUSIVE NOR GATE
SYNCHRONIZES BOTH LTC1144s
TO MINIMIZE RIPPLE
1144 F13
Figure 13. Paralleling for Lower Output Resistance
Related Parts
PART NUMBER DESCRIPTION
COMMENTS
LTC1054
15V, 100mA Inverting Charge Pump
VIN = 3.5V to 15V, VOUT(MAX) = ±15V, IQ = 2.5mA, ISD =
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