LTC1144
Switched-Capacitor
Wide Input Range
Voltage Converter
with Shutdown
FEATURES
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DESCRIPTIO
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Wide Operating Supply Voltage Range: 2V to 18V
Boost Pin (Pin 1) for Higher Switching Frequency
Simple Conversion of 15V to 鈥?5V Supply
Low Output Resistance: 120鈩?Maximum
Power Shutdown to 8碌A with SHDN Pin
Open Circuit Voltage Conversion Efficiency:
99.9% Typical
Power Conversion Efficiency: 93% Typical
Easy to Use
The LTC1144 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 鈥?V to
鈥?8V. 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 to 8碌A 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.
APPLICATI
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Conversion of 15V to
鹵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
TYPICAL APPLICATI
LTC1144
1
2
BOOST
CAP
+
GND
CAP
鈥?/div>
Generating 鈥?5V from 15V
8
7
6
5
10碌F
1144 TA01
Output Voltage vs Load Current, V
+
= 15V
鈥?5
R
OUT
= 56鈩?/div>
T
A
= 25擄C
鈥?4
OUTPUT VOLTAGE (V)
V
+
OSC
SHDN
V
OUT
15V INPUT
+
10碌F
3
4
鈥?5V OUTPUT
鈥?3
鈥?2
鈥?1
鈥?0
0
10
30
40
20
LOAD CURRENT (mA)
50
1144 TA02
U
+
UO
UO
1
1
2
3
4
5
6
7
8
