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PDF LTC1044AIN8 Data sheet ( Hoja de datos )
| Número de pieza | LTC1044AIN8 | |
| Descripción | 12V CMOS Voltage Converter | |
| Fabricantes | Linear Technology | |
| Logotipo |  |
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LTC1044A
12V CMOS
Voltage Converter
FEATURES
s 1.5V to 12V Operating Supply Voltage Range
s 13V Absolute Maximum Rating
s 200µA Maximum No Load Supply Current at 5V
s Boost Pin (Pin 1) for Higher Switching Frequency
s 97% Minimum Open Circuit Voltage Conversion
Efficiency
s 95% Minimum Power Conversion Efficiency
s IS = 1.5µA with 5V Supply When OSC Pin = 0V or V +
s High Voltage Upgrade to ICL7660/LTC1044
APPLICATI S
s Conversion of 10V to ±10V Supplies
s Conversion of 5V to ±5V Supplies
s Precise Voltage Division: VOUT = VIN/2 ±20ppm
s Voltage Multiplication: VOUT = ±nVIN
s Supply Splitter: VOUT = ±VS/2
s Automotive Applications
s Battery Systems with 9V Wall Adapters/Chargers
DESCRIPTIO
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 (VOUT = – VIN), doubled (VOUT = 2VIN), divided
(VOUT = VIN/2) or multiplied (VOUT = ±nVIN).
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 +.
TYPICAL APPLICATI
Generating – 10V from 10V
LTC1044A
1
BOOST
V+ 8
+
10µF
2 CAP+
3 GND
OSC 7
LV 6
4 CAP–
5
VOUT
LTC1044A • TA01
10V INPUT
–10V OUTPUT
10µF
Output Voltage vs Load Current, V + = 10V
0
–1
TA = 25°C
C1 = C2 = 10µF
–2
–3
–4
–5
–6
SLOPE = 45Ω
–7
–8
–9
–10
0 10 20 30 40 50 60 70 80 90 100
LOAD CURRENT (mA)
LTC1044A • TA02
1
1 page  
TEST CIRCUIT
18
27
+ C1 3 LTC1044A 6
10µF 4
5
LTC1044A • TC
COSC
V+ (5V)
IS
EXTERNAL
OSCILLATOR RL
IL
VOUT
C2
10µF
LTC1044A
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 V2
f
RL
C1 C2
LTC1044A • F01
Figure 1. Switched-Capacitor Building Block
Rewriting in terms of voltage and impedance equivalence,
I = V1 – V2 = V1 – V2
1/(f × C1) REQUIV
A new variable, REQUIV, has been defined such that REQUIV
= 1/(f × C1). Thus, the equivalent circuit for the switched-
capacitor network is as shown in Figure 2.
REQUIV
V1
V2
REQUIV
=
f
1
× C1
C2 RL
LTC1044A • F02
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.
5
5 Page 
U
PACKAGE DESCRIPTIO Dimensions in inches (millimeters) unless otherwise noted.
LTC1044A
N8 Package
8-Lead Plastic DIP
0.400
(10.160)
MAX
87 6
5
0.250 ± 0.010
(6.350 ± 0.254)
12
34
0.300 – 0.320
(7.620 – 8.128)
0.009 – 0.015
(0.229 – 0.381)
+0.025
0.325 –0.015
( )8.255
+0.635
–0.381
0.045 – 0.065
(1.143 – 1.651)
0.065
(1.651)
TYP
0.045 ± 0.015
(1.143 ± 0.381)
0.100 ± 0.010
(2.540 ± 0.254)
0.130 ± 0.005
(3.302 ± 0.127)
0.125
(3.175)
MIN
0.020
(0.508)
MIN
0.018 ± 0.003
(0.457 ± 0.076)
N8 0392
S8 Package
8-Lead Plastic SOIC
0.189 – 0.197
(4.801 – 5.004)
8 765
0.228 – 0.244
(5.791 – 6.197)
0.150 – 0.157
(3.810 – 3.988)
0.010
(0.254
–
–
0.020
0.508)
×
45°
0.008 – 0.010
(0.203 – 0.254)
0.016 – 0.050
0.406 – 1.270
0°– 8° TYP
1 2 34
0.053 – 0.069
(1.346 – 1.752)
0.004 – 0.010
(0.101 – 0.254)
0.014 – 0.019
(0.355 – 0.483)
0.050
(1.270)
BSC
SO8 0392
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 represen-
tation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
11
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| Páginas | Total 12 Páginas | |
| PDF Descargar | [ Datasheet LTC1044AIN8.PDF ] | |
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