LTC1044A
12V CMOS
Voltage Converter
FEATURES
s
s
s
s
s
DESCRIPTIO
s
s
s
1.5V to 12V Operating Supply Voltage Range
13V Absolute Maximum Rating
200µA Maximum No Load Supply Current at 5V
Boost Pin (Pin 1) for Higher Switching Frequency
97% Minimum Open Circuit Voltage Conversion
Efficiency
95% Minimum Power Conversion Efficiency
I
S
= 1.5µA with 5V Supply When OSC Pin = 0V or V
+
High Voltage Upgrade to ICL7660/LTC1044
The LTC1044A is a monolithic CMOS switched-capacitor
voltage converter. It plugs in for ICL7660/LTC1044 in
applications where higher input voltage (up to 12V) is
needed. The LTC1044A provides several conversion func-
tions without using inductors. The input voltage can be
inverted (V
OUT
= – V
IN
), doubled (V
OUT
= 2V
IN
), divided
(V
OUT
= V
IN
/2) or multiplied (V
OUT
=
±nV
IN
).
To optimize performance in specific applications, a boost
function is available to raise the internal oscillator fre-
quency by a factor of 7. Smaller external capacitors can be
used in higher frequency operation to save board space.
The internal oscillator can also be disabled to save power.
The supply current drops to 1.5µA at 5V input when the
OSC pin is tied to GND or V
+
.
APPLICATI
s
s
s
s
s
s
s
S
Conversion of 10V to
±10V
Supplies
Conversion of 5V to
±5V
Supplies
Precise Voltage Division: V
OUT
= V
IN
/2
±20ppm
Voltage Multiplication: V
OUT
=
±nV
IN
Supply Splitter: V
OUT
=
±V
S
/2
Automotive Applications
Battery Systems with 9V Wall Adapters/Chargers
TYPICAL APPLICATI
Generating – 10V from 10V
LTC1044A
1
2
BOOST
CAP
+
GND
CAP
–
V
+
OSC
LV
V
OUT
LTC1044A • TA01
Output Voltage vs Load Current, V
+
= 10V
0
8
7
10V INPUT
OUTPUT VOLTAGE (V)
–1
–2
–3
–4
–5
–6
–7
–8
–9
–10
0
T
A
= 25°C
C1 = C2 = 10µF
+
10µF
3
4
6
5
–10V OUTPUT
10µF
10 20 30 40 50 60 70 80 90 100
LOAD CURRENT (mA)
LTC1044A • TA02
U
SLOPE = 45Ω
+
UO
UO
1
LTC1044A
ABSOLUTE
(Note 1)
AXI U
RATI GS
PACKAGE/ORDER I FOR ATIO
TOP VIEW
BOOST 1
CAP
+
2
GND 3
CAP
–
4
8
7
6
5
V
+
OSC
LV
V
OUT
Supply Voltage ........................................................ 13V
Input Voltage on Pins 1, 6 and 7
(Note 2) .............................. – 0.3V < V
IN
< V
+
+ 0.3V
Current into Pin 6 ................................................. 20µA
Output Short-Circuit Duration
V
+
≤
6.5V ................................................. Continuous
Operating Temperature Range
LTC1044AC ............................................ 0°C to 70°C
LTC1044AI ........................................ – 40°C to 85°C
Storage Temperature Range ................ – 65°C to 150°C
Lead Temperature (Soldering, 10 sec)................. 300°C
ORDER PART
NUMBER
LTC1044ACN8
LTC1044AIN8
N8 PACKAGE
8-LEAD PLASTIC DIP
T
JMAX
= 110°C,
θ
JA
= 100°C/W
TOP VIEW
BOOST 1
CAP
+
2
GND 3
CAP
–
4
8
7
6
5
V
+
OSC
LV
V
OUT
ORDER PART
NUMBER
LTC1044ACS8
LTC1044AIS8
S8 PART MARKING
1044A
1044AI
S8 PACKAGE
8-LEAD PLASTIC SOIC
T
JMAX
= 110°C,
θ
JA
= 130°C/W
Consult factory for Military grade parts
ELECTRICAL CHARACTERISTICS
SYMBOL
I
S
PARAMETER
Supply Current
CONDITIONS
V
+
= 5V, C
OSC
= 0pF, T
A
= 25°C, See Test Circuit, unless otherwise noted.
LTC1044AC
LTC1044AI
MIN
TYP
MAX MIN
TYP
MAX
60
15
q
q
q
q
q
q
UNITS
µA
µA
V
R
L
=
∞,
Pins 1 and 7, No Connection
R
L
=
∞,
Pins 1 and 7, No Connection,
V
+
= 3V
R
L
= 10k
R
L
= 10k
I
L
= 20mA, f
OSC
= 5kHz
V
+
= 2V, I
L
= 3mA, f
OSC
= 1kHz
1.5
200
60
15
1.5
200
Minimum Supply Voltage
Maximum Supply Voltage
R
OUT
Output Resistance
12
100
120
310
5
1
95
97
98
99.9
3
20
5
1
95
97
98
99.9
12
100
130
325
f
OSC
P
EFF
Oscillator Frequency
Power Efficiency
Voltage Conversion Efficiency
Oscillator Sink or Source
Current
V
+
= 5V, (Note 3)
V
+
= 2V
R
L
= 5k, f
OSC
= 5kHz
R
L
=
∞
V
OSC
= 0V or V
+
Pin 1 (BOOST) = 0V
Pin 1 (BOOST) = V
+
q
q
3
20
The
q
denotes specifications which apply over the full operating
temperature range; all other limits and typicals T
A
= 25°C.
Note 1:
Absolute maximum ratings are those values beyond which the life
of a device may be impaired.
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 LTC1044A.
Note 3:
f
OSC
is tested with C
OSC
= 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.
2
U
V
Ω
Ω
Ω
kHz
kHz
%
%
µA
µA
W
U
U
W W
W
LTC1044A
TYPICAL PERFOR A CE CHARACTERISTICS
Operating Voltage Range
vs Temperature
14
12
POWER EFFICIENCY (%)
10
8
6
4
2
0
–55 –25
POWER EFFICIENCY (%)
SUPPLY VOLTAGE (V)
0
50
100
25
75
AMBIENT TEMPERATURE (°C)
LTC1044A • TPC01
Output Resistance vs
Oscillator Frequency, V
+
= 5V
500
C1 = C2 = 10µF
OUTPUT RESISTANCE (Ω)
400
C1 = C2 = 1µF
300
T
A
= 25°C
I
L
= 10mA
OUTPUT RESISTANCE (Ω)
POWER CONVERSION EFFICIENCY (%)
200
100
C1 = C2 = 100µF
0
100
1k
10k
OSCILLATOR FREQUENCY (Hz)
100k
LTC1044A • TPC04
Power Conversion Efficiency
vs Load Current, V
+
= 5V
100
POWER CONVERSION EFFICIENCY (%)
P
EFF
POWER CONVERSION EFFICIENCY (%)
90
80
70
60
50
40
30
20
10
0
0
10
40
30
20
50
LOAD CURRENT (mA)
U W
I
S
Using the Test Circuit
Power Efficiency vs
Oscillator Frequency, V
+
= 10V
100
98
96
100µF
I
L
= 1mA
T
A
= 25°C
C1 = C2
Power Efficiency vs
Oscillator Frequency, V
+
= 5V
100
98
96
94
92
90
88
86
84
82
125
80
100
1k
10k
OSCILLATOR FREQUENCY (Hz)
100k
100µF
10µF
I
L
= 15mA
1µF
10µF
1µF
I
L
= 1mA
100µF
T
A
= 25°C
C1 = C2
94
92
90
88
86
84
82
10µF
10µF
100µF
I
L
= 15mA
1µF
1µF
80
100
1k
10k
OSCILLATOR FREQUENCY (Hz)
100k
LTC1044A • G02
LTC1044A • TPC03
Output Resistance vs
Oscillator Frequency, V
+
= 10V
500
T
A
= 25°C
I
L
= 10mA
400
100
90
80
70
60
50
40
30
20
10
0
Power Conversion Efficiency
vs Load Current, V
+
= 2V
10
P
EFF
T
A
= 25°C
C1 = C2 = 10µF
f
OSC
= 1kHz
9
8
SUPPLY CURRENT (mA)
7
I
S
6
5
4
3
2
1
0
0
1
4
3
2
5
LOAD CURRENT (mA)
6
7
300
C1 = C2
= 100µF
C1 = C2
= 10µF
C1 = C2 = 1µF
200
100
0
100
1k
10k
OSCILLATOR FREQUENCY (Hz)
100k
LTC1044A • TPC05
LTC1044A • TPC06
Power Conversion Efficiency
vs Load Current, V
+
= 10V
100
100
90
80
70
60
50
40
30
20
10
0
0
20
80
60
40
100
LOAD CURRENT (mA)
120
T
A
= 25°C
C1 = C2 = 10µF
f
OSC
= 20kHz
I
S
P
EFF
300
270
240
SUPPLY CURRENT (mA)
T
A
= 25°C
C1 = C2 = 10µF
f
OSC
= 5kHz
90
80
SUPPLY CURRENT (mA)
70
60
50
40
30
20
10
0
60
70
210
180
150
120
90
60
30
0
140
LTC1044A • TPC07
LTC1044A • TPC08
3
LTC1044A
TYPICAL PERFOR A CE CHARACTERISTICS
Output Resistance
vs Supply Voltage
1000
T
A
= 25°C
I
L
= 3mA
OUTPUT RESISTANCE (Ω)
OUTPUT VOLTAGE (V)
C
OSC
= 100pF
100
C
OSC
= 0pF
1.0
0.5
0
– 0.5
–1.0
–1.5
–2.0
SLOPE = 250Ω
OUTPUT VOLTAGE (V)
10
0
1
2
3
4 5 6 7 8 9 10 11 12
SUPPLY VOLTAGE (V)
LTC1044A • TPC09
Output Voltage
vs Load Current, V
+
= 10V
10
8
6
T
A
= 25°C
f
OSC
= 20kHz
OUTPUT RESISTANCE (Ω)
400
360
320
280
240
200
160
120
80
40
OSCILLATOR FREQUENCY (Hz)
OUTPUT VOLTAGE (V)
4
2
0
–2
–4
–6
–8
–10
0
10 20 30 40 50 60 70 80 90 100
LOAD CURRENT (mA)
LTC1044A • TPC12
SLOPE = 45Ω
Oscillator Frequency as a
Function of C
OSC
, V
+
= 10V
100k
V
+
= 10V
T
A
= 25°C
PIN 1 = V
+
100k
10k
OSCILLATOR FREQUENCY (kHz)
OSCILLATOR FREQUENCY (Hz)
OSCILLATOR FREQUENCY (Hz)
1k
PIN 1 = OPEN
100
10
1
100
1000
10000
10
EXTERNAL CAPACITOR (PIN 7 TO GND)(pF)
LTC1044A • TPC15
4
U W
Using the Test Circuit
Output Voltage
vs Load Current, V
+
= 5V
5
4
3
2
1
0
–1
–2
–3
–4
SLOPE = 80Ω
T
A
= 25°C
f
OSC
= 5kHz
Output Voltage
vs Load Current, V
+
= 2V
2.5
2.0
1.5
T
A
= 25°C
f
OSC
= 1kHz
–2.5
0
1
2
3 4 5 6 7 8
LOAD CURRENT (mA)
9
10
–5
0
10 20 30 40 50 60 70 80 90 100
LOAD CURRENT (mA)
LTC1044A • TPC11
LTC1044A • TPC10
Output Resistance
vs Temperature
100k
C1 = C2 = 10µF
Oscillator Frequency as a
Function of C
OSC
, V
+
= 5V
T
A
= 25°C
PIN 1 = V
+
V
+
= 2V, f
OSC
= 1kHz
10k
1k
PIN 1 = OPEN
100
V = 5V, f
OSC
= 5kHz
+
V
+
= 10V, f
OSC
= 20kHz
0
50
25
0
75 100
–55 –25
AMBIENT TEMPERATURE (°C)
125
10
1
100
1000
10000
10
EXTERNAL CAPACITOR (PIN 7 TO GND)(pF)
LTC1044A • TPC14
LTC1044A • TPC13
Oscillator Frequency
vs Supply Voltage
35
T
A
= 25°C
C
OSC
= 0pF
Oscillator Frequency
vs Temperature
C
OSC
= 0pF
30
25
20
15
10
5
0
–55 –25
V
+
= 5V
10k
V
+
= 10V
1k
0.1k
0
1
2
3
4 5 6 7 8 9 10 11 12
SUPPLY VOLTAGE (V)
LTC1044A • G16
50
100
25
75
0
AMBIENT TEMPERATURE (°C)
125
LTC1044A • TPC17
LTC1044A
TEST CIRCUIT
V
+
(5V)
I
S
1
2
8
7
LTC1044A
6
5
LTC1044A • TC
+
C1
10µF
3
4
EXTERNAL
OSCILLATOR
R
L
I
L
V
OUT
APPLICATI
S I FOR ATIO
Theory of Operation
To understand the theory of operation of the LTC1044A, a
review of a basic switched-capacitor building block is
helpful.
In Figure 1, 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, discharg-
ing 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)
V1
f
R
L
C1
C2
LTC1044A • F01
R
EQUIV
V1
V2
R
EQUIV
=
1
f
×
C1
Figure 2. Switched-Capacitor Equivalent Circuit
Examination of Figure 3 shows that the LTC1044A has the
same switching action as the basic switched-capacitor
building block. With the addition of finite switch-on resis-
tance and output voltage ripple, the simple theory al-
though 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 typical curve), this simple
theory will explain how the LTC1044A 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. The typical curves for Power Effi-
ciency vs Frequency show this effect for various capacitor
values.
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.
V2
Figure 1. Switched-Capacitor Building Block
Rewriting in terms of voltage and impedance equivalence,
I = V1 – V2 = V1 – V2
1/(f
×
C1) R
EQUIV
A new variable, R
EQUIV
, has been defined such that R
EQUIV
= 1/(f
×
C1). Thus, the equivalent circuit for the switched-
capacitor network is as shown in Figure 2.
+
C
OSC
C2
10µF
U
C2
R
L
LTC1044A • F02
W
U
UO
5
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