LTC1503-1.8/LTC1503-2
High Efficiency Inductorless
Step-Down DC/DC Converters
FEATURES
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DESCRIPTIO
Input Voltage Range: 2.4V to 6V
Fixed Output Voltages: 1.8V
±4%,
2V
±4%
Output Current: Up to 100mA
No Inductors
Typical Efficiency 25% Higher than LDOs
Low Operating Current: 25
µ
A
Low Shutdown Current: 5
µ
A
600kHz Switching Frequency
Shutdown Disconnects Load from V
IN
Soft-Start Limits Inrush Current at Turn-On
Short-Circuit and Overtemperature Protected
Available in 8-Pin MSOP and SO Packages
The LTC
®
1503-1.8/LTC1503-2 are switched capacitor
step-down DC/DC converters that produce a regulated
output from a 2.4V to 6V input. The parts use switched
capacitor fractional conversion to achieve high efficiency
over the entire input range. No inductors are required.
Internal circuitry controls the step-down conversion ratio
to optimize efficiency as the input voltage and load condi-
tions vary. Typical efficiency is 25% higher than that of a
low dropout (LDO) linear regulator.
Regulation is achieved by sensing the output voltage and
enabling the internal switching network as needed to
maintain a fixed output voltage. This method of regulation
enables the parts to achieve high efficiency at extremely
light loads. Low operating current (25µA with no load, 5µA
in shutdown) and low external parts count (two 1µF flying
capacitors and two 10µF bypass capacitors) make the
LTC1503-1.8/LTC1503-2 ideally suited for space con-
strained battery-powered applications. The parts are fully
short-circuit and overtemperature protected.
The LTC1503-1.8/LTC1503-2 are available in 8-pin MSOP
and SO packages.
, LTC and LT are registered trademarks of Linear Technology Corporation.
APPLICATIO S
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Cellular Phones
Handheld Computers
Smart Card Readers
Low Power DSP Supplies
Portable Electronic Equipment
Handheld Medical Instruments
TYPICAL APPLICATIO
Single Li-Ion to 2V DC/DC Converter
80
4
1-CELL Li-Ion OR
3-CELL NiMH
10µF
1µF
2
V
IN
V
OUT
1
10µF
1µF
8
C1
–
C2
–
3
6
C1
+
C2
+
5
7
SHDN/SS GND
V
OUT
= 2V
I
OUT
= 100mA
EFFICIENCY (%)
LTC1503-2
1503-1.8/2 TA01
U
Efficiency vs Input Voltage
100
I
OUT
= 100mA
I
OUT
= 1mA
60
“IDEAL” LDO
40
LTC1503-2
V
OUT
= 2V
20
2
3
4
INPUT VOLTAGE (V)
1503-1.8/2 TA02
U
U
5
6
1
LINER [ LINEAR TECHNOLOGY ]
