LSP5503L
3A 23V Synchronous Buck Converter
General Description
The LSP5503L is a monolithic synchronous buck regulator. The device integrates 90 mΩ MOSFETS that
provide 3A continuous load current over a wide operating input voltage of 4.5V to 23V. Current mode control
provides fast transient response and cycle-by-cycle current limit. An adjustable soft-start prevents inrush
current at turn on.
Features
•
•
•
•
•
•
•
•
•
•
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3A Output Current
Wide 4.5V to 23V Operating Input Range
Fixed 340KHZ Frequency
Integrated Power MOSFET Switches
Output Adjustable from 0.925V to 0.8Vin
Up to 93% Efficiency
Programmable Soft-Start
Stable with Low ESR Ceramic Output Capacitors
Over Current Protection
Short Circuit Protection
In
put Under Voltage Lockout
Package： ESOP-8L
Applications
•
•
•
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Distributed Power Systems
Networking Systems
FPGA, DSP, ASIC Power Supplies
Green Electronics/ Appliances
Notebook Computers
Please be aware that an
Important Notice
concerning availability, disclaimers, and use in critical
applications of LSC products is at the end of this document.
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LSP5503L
3A 23V Synchronous Buck Converter
Block Diagram
CURRENT
SENSE
AMPLIFIER
5V
OVP
1.1V
FB
5
0.3V
OSCILLATOR
2
VIN
RAMP
340/120KHz CLK
1
BS
S Q
R Q
SS
8
0.925V
ERROR
AMPLIFIER
CURRENT
COMPARATOR
6uA
3
SW
COMP
6
EN
7
2.5V
EN OK
LOCKOUT
COMPARATOR
4
GND
1.2V
OVP
IN<4.10V
IN
INTERNAL
REGULATORS
1.5V
SHUTDOWN
COMPARATOR
Ordering Information
LSP 5503L - XX X X
Packing
Output Voltage
Package
Package
R8 : ESOP-8L
Output Voltage
Blank : ADJ
Packing
A : Tape & Reel
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LSP5503L
3A 23V Synchronous Buck Converter
Pin Assignment
ESOP-8L
(TOP View)
BS
VIN
SW
GND
1
2
3
4
Exposed
Pad on
Backside
8
7
6
5
SS
EN
COMP
FB
Pin Descriptions
Pin Name
1
2
3
4
5
6
Name
BS
VIN
SW
GND
FB
COMP
Pin Description
Bootstrap. This pin acts as the positive rail for the high-side switch’s gate driver.
Connect a 0.01uF capacitor between BS and SW.
Input Supply. Bypass this pin to GND with a low ESR capacitor. See Input Capacitor
in the Application Information section.
Switch Output. Connect this pin to the switching end of the inductor.
Ground.
Feedback Input. The voltage at this pin is regulated to 0.925V. Connect to the
resistor divider between output and ground to set output voltage.
Compensation Pin. See Stability Compensation in the Application Information
section.
Enable Input. When higher than 2.7V, this pin turns the IC on. When lower than
1.1V, this pin turns the IC off. Output voltage is discharged when the IC is off. This
pin should not be left open. Recommend to put a 150KW pull-up resistor to Vin for
startup.
Soft-Start Control Input. SS controls the soft-start period. Connect a capacitor from
SS to GND to set the soft-start period. A 0.1uF capacitor sets the soft-start period to
13ms. To disable the soft-start feature, leave SS unconnected.
Exposed Pad. Need to connect to GND pin.
7
EN
8
SS
Exposed Pad
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LSP5503L
3A 23V Synchronous Buck Converter
Absolute Maximum Ratings
(at T
A
=25°C)
Note: Operate over the “Absolute Maximum Ratings” may cause permanent damage to the device.
Exposure to such conditions for extended time may still affect the reliability of the device.
Characteristics
Input Supply Voltage
SW Voltage
BS Voltage
EN, FB, COMP Voltage
Continuous SW Current
Maximum Junction Temperature
Storage Temperature Range
ESOP-8L Thermal Resistance (Junction to Case) (θ
JC
)
ESOP-8L Thermal Resistance (Junction to Ambitent) (θJA)
ESOP-8L Power Dissipation
Moisture Sensitivity
Value
-0.3 to 25
-0.3 to V
IN
+ 0.3
V
SW
– 0.3 to V
SW
+ 6
-0.3 to 5
Internally limited
150
-65 to 150
19
84
1450
Unit
V
V
V
V
A
°C
°C
°C/W
°C/W
mW
Please refer the MSL label on the IC package
bag/carton for detail
Note1: Ratings apply to ambient temperature at 25°C
Recommended Operating Conditions
Characteristics
Input Supply Voltage
Operating Junction Temperature
Min
4.5
-20
Max
23
+125
Unit
V
°C
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LSP5503L
3A 23V Synchronous Buck Converter
Electrical Characteristics
(V
IN
= 12V, T
A
=25°C, unless otherwise specified)
Characteristics
Feedback Voltage
Feedback Overvoltage Threshold
High-Side Switch-On Resistance*
Low-Side Switch-On Resistance*
High-Side Switch Leakage
Upper Switch Current Limit
Lower Switch Current Limit
COMP to Current Sense Limit
Transconductance
Error Amplifier Transconductance
Error Amplifier DC Gain*
Switching Frequency
Short Circuit Switching Frequency
Minimum Duty Cycle*
Maximum Duty Cycle
EN Shutdown Threshold Voltage
EN Shutdown Threshold Voltage
Hysteresis
EN Lockout Threshold Voltage
EN Lockout Hysteresis
Supply Current in Shutdown
IC Supply Current in Operation
Input UVLO Threshold Rising
Input UVLO Threshold Hysteresis
Soft-start Current
Soft-start Period
Thermal Shutdown Temperature*
Note : * Guaranteed by design, not tested.
V
SS
= 0V
C
SS
= 0.1uF
Hysteresis =25°C
UVLO
V
EN
= 0
V
EN
= 3V, V
FB
= 1.0V
V
EN
Rising
3.80
2.2
D
min
D
max
V
EN
Rising
1.1
G
CS
G
EA
A
VEA
f
SW
V
FB
= 0
7.5
92
1.4
180
2.5
150
0.3
1.3
4.0
150
6
13
155
3.0
1.5
4.40
2.7
2
300
ΔI
COMP
= ±10uA
V
EN
= 0V, V
SW
= 0V
Minimum Duty Cycle
From Drain to Source
3.8
Symbol
V
FB
Conditions
4.5V
≤
VIN
≤
23V
Min
0.900
Typ
0.925
1.1
90
70
0.1
4.5
1.2
5.2
900
400
340
100
380
10
Max
0.950
Unit
V
V
mΩ
mΩ
uA
A
A
A/V
uA/V
V/V
KHz
KHz
%
%
V
mV
V
mV
uA
mA
V
mV
uA
mS
°C
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