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For more information www.linear.com/LTC1144
Typical applicaTion
FeaTures DescripTion
Switched-Capacitor
Wide Input Range
Voltage Converter
with Shutdown
The LT C
®
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.
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 toA 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.
applicaTions
n Wide Operating Supply Voltage Range: 2V to 18V
n Boost Pin (Pin 1) for Higher Switching Frequency
n Simple Conversion of 15V to –15V Supply
n Low Output Resistance: 120Ω Maximum
n Power Shutdown to 8µA with SHDN Pin
n Open Circuit Voltage Conversion Efficiency:
99.9% Typical
n Power Conversion Efficiency: 93% Typical
n Easy to Use
n Conversion of 15V to ±15V Supplies
n Inexpensive Negative Supplies
n Data Acquisition Systems
n High Voltage Upgrade to LTC1044 or 7660
n Voltage Division and Multiplications
n Automotive Applications
n Battery Systems with Wall Adapter/Charger L, LT , LT C , LT M , Linear Technology and the Linear logo are registered trademarks of Linear
Technology Corporation. All other trademarks are the property of their respective owners.
Output Voltage vs Load Current, V+ = 15VGenerating –15V from 15V
1
2
3
4
8
7
6
5
BOOST
CAP+
GND
CAP
V+
OSC
SHDN
VOUT
+
+
10µF
15V OUTPUT
15V INPUT
LTC1144
10µF
1144 TA01
LOAD CURRENT (mA)
0 10
OUTPUT VOLTAGE (V)
15
14
13
12
11
10 40
1144 TA02
20 30
50
ROUT = 56Ω
TA = 25°C
LTC1144 TOP vwEw v I’M—H—H—V ULHJU NE PACKAGE HEAD PLASTIC m? TOP VIEW fll—Vflfl UUUU
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absoluTe MaxiMuM raTings
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................................................. C to 70°C
LTC1144I ..............................................40°C to 8C
Storage Temperature Range .................. 6C to 150°C
Lead Temperature (Soldering, 10 sec) ...................300°C
(Note 1)
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 LT C Marketing for parts specified with wider operating temperature ranges.
Consult LT C 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/
1
2
3
4
8
7
6
5
TOP VIEW
BOOST
CAP+
GND
CAP
V+
OSC
SHDN
VOUT
N8 PACKAGE
8-LEAD PLASTIC DIP
TJMAX = 110°C, θJA = 100°C/W
TOP VIEW
1
2
3
4
8
7
6
5
BOOST
CAP+
GND
CAP
V+
OSC
SHDN
VOUT
S8 PACKAGE
8-LEAD PLASTIC SOIC
TJMAX = 110°C, θJA = 130°C/W
pin conFiguraTion
LTC1144 L7 LJUW 3
LTC114 4
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For more information www.linear.com/LTC1144
elecTrical characTerisTics
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.
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.
SYMBOL PARAMETER CONDITIONS
LTC1144C LTC1144I
UNITSMIN TYP MAX MIN TYP MAX
Supply Voltage Range RL = 10k l2 18 2 18 V
ISSupply Current RL = ∞, Pins 1, 6 No Connection,
fOSC = 10kHz
l
1.1
1.3
1.1
1.6
mA
mA
SHDN = 0V, RL = ∞, Pins 1, 7
No Connection
l0.008 0.03 0.008 0.035 mA
V+ = 5V, RL = ∞, Pins 1, 6
No Connection, fOSC = 4kHz
l
0.10
0.13
0.10
0.15
mA
mA
V+ = 5V, SHDN = 0V, RL = ∞,
Pins 1, 7 No Connection
l0.002 0.015 0.002 0.018 mA
ROUT Output Resistance V+ = 15V, IL = 20mA at 10kHz
l
56 100
120
56 100
140
Ω
Ω
V+ = 5V, IL = 3mA at 4kHz l90 250 90 300 Ω
fOSC Oscillator Frequency V+ = 15V (Note 3)
V+ = 5V
10
4
10
4
kHz
kHz
Power Efficiency RL = 2k at 10kHz l90 93 90 93 %
Voltage Conversion Efficiency RL = ∞ l97.0 99.9 97.0 99.9 %
Oscillator Sink or Source Current V+ = 5V (VOSC = 0V to 5V)
V+ = 15V (VOSC = 0V to 15V)
0.5
4
0.5
4
µA
µA
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.
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Typical perForMance characTerisTics
Oscillator Frequency as a
Function of COSC
Oscillator Frequency
vs Temperature Output Voltage vs Load Current
Output Voltage vs Load Current
Supply Current as a Function of
Oscillator Frequency
Power Conversion Efficiency and
Supply Current vs Load Current
Output Resistance
vs Supply Voltage
Output Resistance vs
Temperature
Oscillator Frequency
vs Supply Voltage
SUPPLY VOLTAGE (V)
2
0
OUTPUT RESISTANCE (Ω)
50
100
150
200
6 10 14
18
LTC1144 • TPC01
250
300
4 8 12 16
TA = 25°C
EXTERNAL CAPACITANCE (PIN 7 TO GND), COSC
(pF)
1
OSCILLATOR FREQUENCY (kHz)
1
10
10000
LTC1144 • TPC04
0.1
0.01 10 100 1000
1000
100
TA = 25°C
V+ = 15V
BOOST = OPEN OR GROUND
BOOST = V+
LOAD CURRENT (mA)
0
5
OUTPUT VOLTAGE (V)
4
3
2
–1
0
510 15 20
LTC1144 • TPC07
25
30
TA = 25°C
V+ = 5V
C1 = C2 = 10µF
BOOST = OPEN
ROUT = 90Ω
TEMPERATURE (°C)
55
100
120
25 75
80
60
–25 0 50 100
40
20
V+ = 5V
IL = 3mA
V+ = 15V
IL = 20mA
TEMPERATURE (°C)
55 –25
OSCILLATOR FREQUENCY (kHz)
10
100
1000
0 25 50 75 100
125
LTC1144 • TPC05
1
BOOST = V+
BOOST = OPEN OR GROUND
TA = 25°C
V+ = 15V
OSCILLATOR FREQUENCY (kHz)
0.01
SUPPLY CURRENT (µA)
100
1000
100
LTC1144 • TPC08
10
10.1 110
10000
TA = 25°C
C1 = C2 = 10µF
V+ = 15V
V+ = 5V
SUPPLY VOLTAGE (V)
2
OSCILLATOR FREQUENCY (kHz)
10
100
1000
6 10 144 8 12 16
18
LTC1144 • TPC03
1
TA = 25°C
COSC = 0
BOOST = V+
BOOST = OPEN OR GROUND
LOAD CURRENT (mA)
0
–15
OUTPUT VOLTAGE (V)
–10
5
0
10 20 30 40
LTC1144 • TPC06
50
60
TA = 25°C
V+ = 15V
C1 = C2 = 10µF
BOOST = OPEN
ROUT = 56Ω
LOAD CURRENT (mA)
0
POWER CONVERSION EFFICIENCY (%)
SUPPLY CURRENT (mA)
60
80
100
40
LTC1144 • TPC09
40
20
0
60
80
100
40
20
0
10 20 30 50
PEFF
IS
TA = 25°C
V+ = 15V
C1 = C2 = 10µF
BOOST = OPEN
(SEE TEST CIRCUIT)
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Typical perForMance characTerisTics
Ripple Voltage vs Load Current Output Voltage vs Load Current Output Voltage vs Load Current
Power Conversion Efficiency and
Supply Current vs Load Current
Power Conversion Efficiency
vs Oscillator Frequency
Output Resistance
vs Oscillator Frequency
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.
GND (Pin 3): Ground Reference.
CAP (Pin 4): Negative Terminal for Pump Capacitor.
VOUT (Pin 5): Output of the Converter.
SHDN (Pin 6): Shutdown Pin. Tie to V+ pin or leave float-
ing for normal operation. Tie to ground when in shutdown
mode.
OSC (Pin 7): Oscillator Input Pin. This pin can be overdriven
with an external clock or can be slowed down by connect-
ing an external capacitor between this pin and ground.
V+ (Pin 8): Input Voltage.
LOAD CURRENT (mA)
0
POWER CONVERSION EFFICIENCY (%)
SUPPLY CURRENT (mA)
60
80
100
16
LTC1144 • TPC10
40
20
0
30
40
50
20
10
0
4812 20
PEFF
IS
TA = 25°C
V+ = 5V
C1 = C2 = 10µF
BOOST = OPEN
(SEE TEST CIRCUIT)
LOAD CURRENT (mA)
0.01
0
RIPPLE VOLTAGE (mV)
500
1000
1µF
1µF
1500
0.1 1
LTC1144 • TPC13
10
100
0.1µF
10µF
10µF
V+ = 5V
TA = 25°C
C1 = C2
BOOST = 5V
BOOST =
OPEN
0.1µF
OSCILLATOR FREQUENCY (kHz)
0.1
70
POWER CONVERSION EFFICIENCY (%)
90
95
100
1 10
100
LTC1144 • TPC11
85
80
75
TA = 25°C, V+ = 15V
BOOST = OPEN
IL = 20mA
IL = 3mA
1µF
1µF
10µF
10µF
100µF
100µF
LOAD CURRENT (mA)
4
OUTPUT VOLTAGE (V)
3
–2
–1
0
0.001 0.1 1
100
LTC1144 • G14
5
0.01 10
0.1µF
0.1µF 10µF
10µF
1µF
1µF
V+ = 5V
TA = 25°C
C1 = C2
BOOST = 5V
BOOST = OPEN
OSCILLATOR FREQUENCY (kHz)
0.1
0
OUTPUT RESISTANCE (Ω)
2000
3000
1 10
100
LTC1144 • TPC12
1000
1µF10µF
100µF
TA = 25°C
V+ = 15V
LOAD CURRENT (mA)
10
OUTPUT VOLTAGE (V)
5
0
0.001 0.1 1
100
LTC1144 • TPC15
15
0.01 10
V+ = 15V
TA = 25°C
C1 = C2
BOOST = 15V
0.1µF
0.1µF 1µF
1µF
10µF
10µF
BOOST = OPEN
pin FuncTions
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TesT circuiT
applicaTions inForMaTion
1
2
3
4
8
7
6
5
+
+
C1
10µF
C2
10µF
IS
V
OUT
V+
15V
IL
RL
EXTERNAL
OSCILLATOR
COSC
1144 F01
LTC1144
Figure 1.
Figure 2. Switched-Capacitor Building Block
Figure 3. Switched-Capacitor Equivalent Circuit
Figure 4. LTC1144 Switched-Capacitor
Voltage Converter Block Diagram
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, capaci-
tor 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:
q = q1 – q2 = C1(V1 – V2)
If the switch is cycled f times per second, the charge
transfer per unit time (i.e., current) is:
I = f × ∆q = f × C1(V1 – V2)
Rewriting in terms of voltage and impedance equivalence,
I=
V1V2
1
f×C1
=
V1V2
REQUIV
A new variable REQUIV has been defined such that
V2
RL
C2
C1
V1
f
1144 F02
V2
RL
R
EQUIV
C2
V1
1144 F03
R
EQUIV =1
f × C1
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 on-
resistance 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
SHDN
(6)
OSC
(7)
10X
(1)
BOOST
1144 F04
OSC ÷2
V+
(8) SW1 SW2
CAP+
(2)
CAP
(4)
GND
(3)
VOUT
(5)
C2
C1
+
+
φ
φ
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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.
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.
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, typicallyA, 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.
Figure 6. Oscillator
Figure 7. External Clocking
OSCILLATOR FREQUENCY (kHz)
0.1
POWER CONVERSION EFFICIENCY (%)
OUTPUT RESISTANCE (Ω)
100
95
90
85
80
75
70
600
500
400
300
200
100
0
1 10 100
1144 F05
V+ = 15V, C1 = C2 = 10µF
IL = 20mA, TA = 25°C
POWER
CONVERSION
EFFICIENCY
OUTPUT
RESISTANCE
OSC
(7)
SCHMITT
TRIGGER
BOOST
(1)
1144 F06
9I
9I
I
I
V
+
GND
(3)
≈20pF
1
2
3
4
8
7
6
5
+
+
C1
OSC INPUT
NC
REQUIRED FOR
TTL LOGIC
C2
100k
(V+)
V
+
1144 F07
LTC1144
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LTC114 4
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For more information www.linear.com/LTC1144
Typical applicaTions
Negative Voltage Converter
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.
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.
At an oscillator frequency of 10kHz and C1 = 10µF, the
first term is:
REQUIV =
1
fOSC / 2
( )
×C1=
1
5×103×10×106=20
Notice that the above equation for REQUIV is not a capaci-
tive 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 imped-
ance 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.
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.
Figure 8. Negative Voltage Converter
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 cir-
cuit 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).
Figure 11. Battery Splitter
1
2
3
4
8
7
6
5
+
+
10µF
10µF
V
+
2V TO 18V
VOUT = –V
+
T
MIN
≤ T
A
≤ T
MAX
1144 F08
LTC1144
1
2
3
4
8
7
6
5+
+
+
+
V
IN
2V TO 18V
VOUT = 2(VIN
– 1)
10µF 10µF
Vd
1N4148 Vd
1N4148
1144 F09
LTC1144
1
2
3
4
8
7
6
5
+
+C2
10µF
C1
10µF
V
+
4V TO 36V
1144 F10
LTC1144
±0.002%
T
MIN TA ≤ TMAX
IL ≤ 100nA
V+
2
1
2
3
4
8
7
6
5
+
+
C2
10µF
C1
10µF
OUTPUT
COMMON
VB/2
9V
VB/2
9V
1144 F11
LTC1144
VB
18V
+
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package DescripTion
Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings.
N8 REV I 0711
.065
(1.651)
TYP
.045 – .065
(1.143 – 1.651)
.130 ±.005
(3.302 ±0.127)
.020
(0.508)
MIN
.018 ±.003
(0.457 ±0.076)
.120
(3.048)
MIN
.008 – .015
(0.203 – 0.381)
.300 – .325
(7.620 – 8.255)
.325 +.035
–.015
+0.889
–0.381
8.255
( )
1 2 34
87 65
.255 ±.015*
(6.477 ±0.381)
.400*
(10.160)
MAX
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)
.100
(2.54)
BSC
N Package
8-Lead PDIP (Narrow .300 Inch)
(Reference LTC DWG # 05-08-1510 Rev I)
LTC1144 58 Package 4L E, 2 DRAWWG NOT To SCALE 3 THESE mMENSIONS DO NOT WCLUDE M0 MOLD FLASH DR PRDTRUSmNs SHALL N 4 PW ‘ CAN BE BEVEL EDGE 0R AmMPLE
LTC114 4
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For more information www.linear.com/LTC1144
package DescripTion
Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings.
.016 – .050
(0.406 – 1.270)
.010 – .020
(0.254 – 0.508)× 45°
0°– 8° TYP
.008 – .010
(0.203 – 0.254)
SO8 REV G 0212
.053 – .069
(1.346 1.752)
.014 – .019
(0.355 – 0.483)
TYP
.004 – .010
(0.101 0.254)
.050
(1.270)
BSC
1234
.150 – .157
(3.810 – 3.988)
NOTE 3
8765
.189 – .197
(4.801 – 5.004)
NOTE 3
.228 – .244
(5.791 – 6.197)
.245
MIN .160 ±.005
RECOMMENDED SOLDER PAD LAYOUT
.045 ±.005
.050 BSC
.030
±.005
TYP
INCHES
(MILLIMETERS)
NOTE:
1. DIMENSIONS IN
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
S8 Package
8-Lead Plastic Small Outline (Narrow .150 Inch)
(Reference LTC DWG # 05-08-1610 Rev G)
LTC1144 L7 LJUW 1 1
LTC114 4
11
1144fa
For more information www.linear.com/LTC1144
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no representa-
tion that the interconnection of its circuits as described herein will not infringe on existing patent rights.
revision hisTory
REV DATE DESCRIPTION PAGE NUMBER
A 04/14 Change 0.0002% to 0.002% under the Ultra-Precision Voltage Divider section. 8
LTC1144
LTC114 4
12
1144fa
For more information www.linear.com/LTC1144
LINEAR TECHNOLOGY CORPORATION 1994
LT 0414 REV A • PRINTED IN USA
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 FAX: (408) 434-0507 www.linear.com/LTC1144
relaTeD parTs
Typical applicaTion
PART NUMBER DESCRIPTION COMMENTS
LTC1054 15V, 100mA Inverting Charge Pump VIN = 3.5V to 15V, VOUT(MAX) = ±15V, IQ = 2.5mA, ISD = <1µA, DIP-8,
S0-8 Packages
LTC1046 6V, 100mA Inverting Charge Pump VIN = 1.5V to 6V, VOUT(MAX) = 3V, IQ = 200µA, ISD = <1µA, SO-8 Package
LT
®
3463/
LT3463A
250mA (ISW), Boost/Inverter Dual, Micropower
DC/DC Converter with Integrated Schottky Diodes
VIN = 2.4V to 15V, VOUT(MAX) = ±40V, IQ = 40µA, ISD = <1µA, DFN Package
LT1615/
LT1615-1
300mA/80mA ISW, Constant Off-Time, High Efficiency
Step-Up DC/DC Converter
VIN = 1.2V to 15V, VOUT(MAX) = 34V, IQ = 20µA, ISD = <1µA, ThinSOT Package
LT3467/
LT3467A
1.1A (ISW), 1.3MHz/2.1MHz, High Efficiency Step-Up
DC/DC Converter with Integrated Soft-Start
VIN = 2.4V to 16V, VOUT(MAX) = 40V, IQ = 1.2mA, ISD = <1µA, ThinSOT Package
LT1931/
LT1931A
1A (ISW), 1.2MHz/2.2MHz High Efficiency Inverting
DC/DC Converter
VIN = 2.6V to 16V, VOUT(MAX) = 34V, IQ = 4.2mA/5.5mA, ISD = <1µA,
ThinSOT Package
Regulated –5V Output Voltage
Figure 12 shows a regulated –5V output with a 9V input.
With a 0mA to 5mA load current, the ROUT is below 20Ω.
Paralleling for Lower Output Resistance
Additional flexibility of the LTC1144 is shown in Figure 13.
Tw o LTC1144s are connected in parallel to provide a lower
effective output resistance. However, if the output resis-
tance 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.
Figure 12. A Regulated –5V Supply
Figure 13. Paralleling for Lower Output Resistance
1
2
3
4
8
7
6
5
+
+
1µF
100µF
5V
9V
36k
300k
1144 F12
LTC1144
2N2369
VOUT = –(V+
)
V
+
C1
10µF
C2
20µF
1144 F13
1
2
3
4
8
7
6
5
LTC1144
+
+
C1
10µF
1/4 CD4077*
* THE EXCLUSIVE NOR GATE
SYNCHRONIZES BOTH LTC1144s
TO MINIMIZE RIPPLE
1
2
3
4
8
7
6
5
LTC1144
+