Liteon Semiconductor Corporation
LSP1084
5A Low Dropout Linear Regulator
FEATURES
1.5V maximum dropout at full load current
Fast transient response
Output current limiting
Built-in thermal shutdown
Good noise rejection
3-Terminal Adjustable or Fixed 1.5V, 1.8V, 2.5V,
3.3V, 5.0V
GENERAL DESCRIPTION
The LSP1084 is a series of low dropout three-terminal
regulators with a dropout of 1.5V at 5A output current.
The LSP1084 series provides current limiting and
thermal shutdown. Its circuit includes a trimmed
bandgap reference to assure output voltage accuracy
to be within 2% for 1.5V, 1.8V, 2.5V, 3.3.V, 5.0V and
adjustable versions. Current limit is trimmed to ensure
specified output current and controlled short-circuit
current. On-chip thermal shutdown provides protection
against any combination of overload and ambient
temperature that would create excessive junction
temperature.
The LSP1084 has an adjustable version that can
provide the output voltage from 1.25V to 12V with only
two external resistors.
The LSP1084 series is available in the industry
standard TO220-3L, TO263-3L and TO252-3L power
packages.
(3) TO252-3L
V
IN
V
OUT
ADJ/GND
3
2
1
Metal Tab V
OUT
V
IN
V
OUT
(TAB)
ADJ/GND
APPLICATIONS
PC Motherboard
LCD Monitor
Graphic Card
DVD-video player
NIC/Switch
Telecom Equipment
ADSL Modem
Printer and other Peripheral Equipment
PIN CONFIGURATION
(1) TO220-3L
3
2
1
Metal Tab V
OUT
V
IN
V
OUT
ADJ/GND
(2) TO263-3L
3
2
1
Metal Tab V
OUT
BLOCK DIAGRAM
3 INPUT
Thermal
Protection
-
+
2 OUTPUT
For Adjustable Output, disconnect A1 and A2, connect B
For Fixed Output,connect A1 and A2, disconnect B
A1
B
A2
1 ADJ/GND
1/10
Rev1.4
Liteon Semiconductor Corporation
LSP1084
5A Low Dropout Linear Regulator
ABSOLUTE MAXIMUM RATINGS (NOTE 1)
Symbol
Parameter
Rating
Unit
V
IN
Input Voltage
12
V
T
J
Maximum Junction Temperature
150
℃
T
S
Storage Temperature
-65~150
℃
T
LEAD
Lead Temperature (10 sec.)
300
℃
Note 1: Stresses greater than those listed under“Absolute Maximum Ratings” may cause permanent damage to the
device. These are stress rating only, and functional operation of the device at these or any other conditions beyond
those indicated under “Recommended Operating Conditions” is not implied. Exposure to “Absolute Maximum
Ratings” for extended periods may affect device reliability.
RECOMMENDED OPERATING CONDITIONS
Symbol
V
IN
T
J
Parameter
Input Voltage
Operating Junction Temperature Range
Rating
12
-20~150
Unit
V
℃
ELECTRICAL CHARACTERISTICS
Operating Conditions: V
IN
≤10V,
T
J
=25
℃
, unless otherwise specified
Parameter
Reference
Voltage
Symbol
V
REF
LSP1084 -Adj
LSP1084 -1.5
LSP1084 -1.8
Output Voltage
V
OUT
LSP1084 -2.5
LSP1084 -3.3
LSP1084 -5.0
Line Regulation
Reg
LINE
LSP1084-XXX
LSP1084 -Adj
LSP1084 -1.5
LSP1084 -1.8
LSP1084 -2.5
LSP1084 -3.3
LSP1084 -5.0
LSP1084-XXX
LSP1084-XXX
LSP1084-XXX
LSP1084-XXX
Test Condition
I
O
=10mA, V
IN
-V
OUT
=1.5V
I
O
=10mA,1.5V≤V
IN
-V
OUT
≤8V
I
O
=10mA, V
IN
=3V
I
O
=10mA, 3V≤V
IN
≤10V
I
O
=10mA, V
IN
=3.3V
I
O
=10mA, 3.3V≤V
IN
≤10V
I
O
=10mA, V
IN
=4V
I
O
=10mA, 4V≤V
IN
≤10V
I
O
=10mA, V
IN
=4.8V
I
O
=10mA, 4.8V≤V
IN
≤10V
I
O
=10mA, V
IN
=6.5V
I
O
=10mA, 6.5V≤V
IN
≤12V
I
O
=10mA,1.5V≤V
IN
-V
OUT
≤7V
I
O
=10mA,1.5V≤V
IN
-V
OUT
≤10V
VIN= 3V, 10mA<Io<5A
VIN= 3V, 10mA<Io<5A
VIN= 3.3V, 10mA<Io<5A
VIN= 4V, 10mA<Io<5A
VIN= 5V, 10mA<Io<5A
VIN= 6.5V, 10mA<Io<5A
I
OUT
= 5A ,∆V
OUT
=1%V
OUT
V
IN
-V
OUT
=3V
F=120Hz,C
OUT
=25uF
Tantalum, V
IN
-V
OUT
=3V
I
O
=10mA
Min.
1.225
1.225
1.485
1.470
1.782
1.764
2.475
2.450
3.267
3.235
4.950
4.900
Typ.
1.250
1.250
1.5
1.5
1.8
1.8
2.5
2.5
3.3
3.3
5.0
5.0
0.2
0.2
1
12
15
20
26
40
1.3
60
0.5
Max.
1.275
1.275
1.515
1.530
1.818
1.836
2.525
2.550
3.333
3.365
5.050
5.100
0.5
0.5
15
18
25
33
50
1.5
70
Unit
V
V
V
V
V
V
V
V
%
%
%
mV
mV
mV
mV
mV
V
A
dB
%
Load Regulation
Reg
Load
Dropout Voltage
Current Limit
Ripple Rejection
Temperature
Stability
V
IN
-
OUT
I
LIMT
5.1
2/10
Rev1.4
Liteon Semiconductor Corporation
LSP1084
5A Low Dropout Linear Regulator
ELECTRICAL CHARACTERISTICS (CONTINUED)
Operating Conditions: V
IN
≤10V,
T
J
=25
℃
, unless otherwise specified
Parameter
Adjust Pin Current
Adjust Pin Current Change
Minimum Load Current(ADJ)
Quiescent Current
Long-term Stability
RMS Output Noise
(% of V
OUT
)
Power Dissipation
Thermal Resistance,
Junction to Ambient
Thermal Resistance,
Junction to case
Thermal Shutdown
Thermal Shutdown
Hysteresis
Symbol
Test Condition
I
O
=10mA~5A, 1.5V≤V
IN
-V
OUT
≤10V
I
O
=10mA~5A, 1.5V≤V
IN
-V
OUT
≤10V
LSP1084
1.5V≤V
IN
-V
OUT
≤10V
V
IN
=V
OUT
+1.25V
T
A
=125℃, 1000hrs
T
A
=25℃, 10Hz≤f≤10kHz
Pd
TO220-3L
TO263-3L
TO252-3L
TO220-3L
TO263-3L
TO252-3L
TO220-3L
TO263-3L
TO252-3L
Junction Temperature
Min.
Typ.
60
0.2
5
5
0.3
0.003
1.6
1.6
1.2
45
45
55
2.7
2.7
10
150
25
Max.
120
5
10
10
Unit
µA
µA
mA
mA
%
%
W
℃/
W
℃/
W
℃
℃
Iq
θ
JA
θ
JC
TYPICAL APPLICATIONS
LSP1084-ADJ
Vin
+
Vin
ADJ
100uF
Vout
R1
+
Vout
100uF
R2
Vout=Vref*(1+R2/R1)+Iadj*R2
The LSP1084 keeps a constant 1.25V between the output pin and the adjust pin. By placing a resistor R1 across
these two pins a constant current flows through R1, adding to the Iadj current and into the R2 resistor producing a
voltage equal to the (1.25/R1)*R2+Iadj*R2 which will be added to the 1.25V to set the output voltage. This is
summarized in the above equation. Since the minimum load current requirement of the LSP1084 is 10mA, R1 is
typically selected to be 121Ω resistor so that it automatically satisfies the minimum current requirement. Notice that
since Iadj is typically in the range of 50uA it only adds a small error to the output voltage and should only be
considered when a very precise output voltage setting is required. For example, in a typical 3.3V application where
R1=121Ω and R2=200Ω the error due to Iadj is only 0.3% of the nominal set point.
Vin=6.5V
100uF
+
LSP1084-5.0
Vin
GND
Vout
+
5V at 5A
100uF
3/10
Rev1.4
Liteon Semiconductor Corporation
LSP1084
5A Low Dropout Linear Regulator
TYPICAL APPLICATIONS (CONTINUED)
Stability
The LSP1084 requires the use of an output capacitor as part of the frequency compensation in order to make the
regulator stable. For most applications a minimum of 100uF aluminum electrolytic capacitor insures both stability
and good transient response.
Thermal Design
The LSP1084 incorporates an internal thermal shutdown that protects the device when the junction temperature
exceeds the maximum allowable junction temperature. Although this device can operate with junction temperatures
in the range of 150℃, it is recommended that the selected heat sink be chosen such that during maximum
continuous load operation the junction temperature is kept below the temperature.
Pd=Vout*Iout
Tj=T
A
+Pd*θ
JA
<150℃
Layout Consideration
The output capacitors must be located as close to the Vout terminal of the device as possible. It is recommended to
use a section of a layer of the PC board as a plane to connect the Vout pin to the output capacitors to prevent any
high frequency oscillation that may result due to excessive trace inductance.
TYPICAL PERFORMANCE CHARACTERISTICS
Dropout Voltage vs Output Current
1.50
1.45
1.40
1.35
1.30
1.25
1.20
1.15
1.10
1.05
1.00
0.95
0.90
0.85
0.80
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0
Output Current (A)
2.53
2.52
Output Voltage (V)
2.51
2.50
2.49
2.48
2.47
0
Output Voltage vs Temperature
Dropout Voltage (V)
25
50
75
T
J
(℃)
100
125
0.0
Line Regulation (mV)
-0.2
-0.4
-0.6
-0.8
-0.1
0
Line Regulation vs Temperature
Adjust Pin Current (
µ
A)
25
50
75
T
J
(℃)
100
125
80
75
70
65
60
55
50
45
40
35
30
25
20
Adjust Pin Current vs Output Current
0
1
2
3
4
Output Current (A)
5
4/10
Rev1.4
Liteon Semiconductor Corporation
LSP1084
5A Low Dropout Linear Regulator
TYPICAL PERFORMANCE CHARACTERISTICS (CONTINUED)
Dropout Voltage vs Temperature
Short Circuit Current (A)
Short Circuit Current vs Dropout Voltage
8
7
6
5
4
3
2
1
0
1.40
Dropout Voltage (V)
1.35
1.30
1.25
1.20
0
25
50
75
T
J
(℃)
100
125
0
2
4
6
8
Dropout Voltage (V)
10
12
Load Transient Response
Line Transient Response
Vin=5.5V, Vout=2.5V Io=100mA to 5A Cin=Cout=100µF(tan)
Vin=4.5V to 6.5V Vout=2.5V Io=200mA Cin=Cout=100µF(tan)
5/10
Rev1.4
嵌入式系统
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