Datasheet

1
LTC1144
Switched-Capacitor
Wide Input Range
Voltage Converter
with Shutdown
U
A
O
PP
L
IC
AT
ITY
P
I
CA
L
Output Voltage vs Load Current, V
+
= 15V
S
F
EA
T
U
RE
D
U
ESCRIPTIO
■
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
■
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 –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 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.
U
S
A
O
PP
L
IC
AT
I
■
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
LOAD CURRENT (mA)
010
OUTPUT VOLTAGE (V)
–15
–14
–13
–12
–11
–10
40
1144 TA02
20
30
50
R
OUT
= 56Ω
T
A
= 25°C
1
2
3
4
8
7
6
5

BOOST
CAP
+

GND
CAP
–
V
+

OSC
SHDN
V
OUT
+
+
10µF
–15V OUTPUT
15V INPUT
LTC1144
10µF
1144 TA01
Generating –15V from 15V