Liteon Semiconductor Corporation
LSP3103
500mA Synchronous Step-Down Converter
FEATURES
High Efficiency : Up to 96%
1.5MHz Constant Switching Frequency
500mA Output Current at V
IN
=3.6V, V
OUT
=1.2V,
Integrated Main switch and synchronous rectifier.
No Schottky Diode Required
2.5V to 6.5V Input Voltage Range
Output Voltage as low as 0.6V
100% Duty Cycle in Dropout
Low Quiescent Current : 300µA
＜1µA
Shutdown Current
Slope Compensated Current Mode Control for
Excellent Line and Load Transient Response
Short Circuit and Thermal Fault Protection
Space Saving 5-pin SOT23 package
GENERAL DESCRIPTION
The LSP3103 is a 1.5MHz constant frequency; slope
compensated current mode PWM step-down
converter. The device integrates a main switch and a
synchronous rectifier for high efficiency without an
external Schottky diode. It is ideal for powering
portable equipment that runs from a single cell
lithium-Ion (Li+) battery. The LSP3103 can supply
500mA of load current from a 2.5V to 6.5V input
voltage. The output voltage can be regulated as low as
0.6V. The LSP3103 can also run at 100% duty cycle for
low dropout operation, extending battery life in portable
system. Idle mode operation at light loads provides
very low output ripple voltage for noise sensitive
applications.
The LSP3103 is offered in a low profile 5-pin, SOT
package, and is available in an adjustable version and
fixed output voltage of 1.2V, 1.8V.
APPLICATIONS
Cellular and Smart Phones
PDAs
MP3 Player
Digital Still and Video Cameras
Portable instruments
Microprocessors and DSP Core Supplies
Wireless and DSL Modems
PIN CONFIGURATION
(Top View)
Run
GND
1
2
3
5
V
FB
/V
OUT
SW
4
V
IN
PIN DESCRIPTION
Pin Number
1
2
3
4
Pin Name
RUN
GND
SW
V
IN
Pin Function
Regulator Enable control input. Drive RUN above 1.5V to turn on the part.
Drive RUN below 0.3V to turn it off. In shutdown, all functions are disable
drawing
＜1µA
supply current. Do not leave RUN floating.
Ground
Power Switch Output. It is the Switch node connection to inductor. This pin
connects to the drains of the internal P-CH and N-CH MOSFET switches.
Supply Input Pin. Must be closely decoupled to GND, pin2, with a 2.2µF or
greater ceramic capacitor.
V
FB
(LSP3103): Feedback Input Pin. Connected FB to the center point of
the external resistor divider. The feedback threshold voltage is 0.6V.
V
OUT
(LSP3103-1.2/1.8): Output Voltage Feedback Pin. An internal resistive
divider divides the output voltage down for comparison to the internal
reference voltage.
5
V
FB
/V
OUT
1/9
Rev1.2
Liteon Semiconductor Corporation
LSP3103
500mA Synchronous Step-Down Converter
BLOCK DIAGRAM
V
FB
/V
OUT
*
Note: For adjustable output, R1and R2 is external.
THERMAL RESISTANCE (NOTE 1)
Package
θ
JA
(℃/W)
θ
JC
(℃/W)
SOT23-5L
220
110
Note 1: Thermal Resistance is specified with approximately 1 square of 1 oz cooper.
ABSOLUTE MAXIMUM RATINGS (NOTE 2)
Parameter
Rating
Unit
Input Supply Voltage
-0.3 to +7
V
RUN, V
FB
Voltages
-0.3 to V
IN
+0.3
V
-0.3 to V
IN
+0.3
V
SW，Vout Voltages
Peak SW Sink and Source Current
800
mA
-40 to +85
Operating Temperature Range
℃
+125
Junction Temperature (Note 3)
℃
-65 to 150
Storage Temperature Range
℃
+300
Lead Temperature ( solding, 10 sec.)
℃
Note 2: Absolute Maximum Ratings are those values beyond which the life of a device may be impaired.
Note 3: T
J
is calculated from the ambient temperature T
A
and power dissipation P
D
according to the following formula:
T
J
=T
A
+P
D
×θ
JA
ELECTRICAL CHARACTERISTICS (NOTE 4)
2/9
Rev1.2
Liteon Semiconductor Corporation
LSP3103
500mA Synchronous Step-Down Converter
(V
IN
=V
RUN
=3.6V, T
A
=25℃, Unless otherwise noted)
Parameter
Input Voltage Range
Input DC Supply Current
Active Mode
Shutdown Mode
Regulated Feedback Voltage
V
FB
Input Bias Current
Reference Voltage Line Regulation
Regulated Output Voltage
Output Voltage Line Regulation
Output Voltage Load Regulation
Maximum Output Current
Oscillator Frequency
R
DS(ON)
of P-CH MOSFET
R
DS(ON)
of N-CH MOSFET
Peak Inductor Current
Condition
V
FB
=0.5V
V
FB
=0V, V
IN
=4.2V
T
A
=+25℃
T
A
=0℃≤T
A
≤85℃
T
A
=-40℃≤T
A
≤85℃
V
FB
=0.65V
V
IN
=2.5V to 5.5V, V
OUT
=V
FB
(R2=0)
LSP3103C12AD: -40℃≤T
A
≤85℃
LSP3103C18AD: -40℃≤T
A
≤85℃
V
IN
=2.5V to 5.5V, I
OUT
=10mA
I
OUT
from 0 to 500mA
V
IN
=3.0V
V
FB
=0.6V or V
OUT
=100%
I
SW
=300mA
I
SW
=-300mA
V
IN
=3V, V
FB
=0.5V or V
OUT
=90%,
Duty Cycle＜35%
V
RUN
=0V, V
SW
=0V or 5V, V
IN
=5V
-40℃≤T
A
≤85℃
0.5880
0.5865
0.5820
Min.
2.5
Typ.
300
0.1
0.6000
0.6000
0.6000
0.04
1.200
1.800
0.04
0.5
1.5
0.50
0.45
0.60
Max.
6.5
500
1.0
0.6120
0.6135
0.6180
±30
0.40
1.236
1.854
0.40
1.8
0.60
0.55
0.80
Unit
V
µA
V
V
V
nA
%/V
V
V
%/V
%
mA
MHz
Ω
Ω
A
1.164
1.746
500
1.2
0.55
SW Leakage
±0.01
±1
µA
0.55
1.30
V
RUN Threshold
RUN Leakage Current
±0.01
±1
µA
Note 4: 100% production test at +25℃. Specifications over the temperature range are guaranteed by design and
characterization.
TYPICAL PERFORMANCE CHARACTERISTICS
3/9
Rev1.2
单片机
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