Eorex EP1084D15B 5a low dropout linear regulator Datasheet

eorex
(Preliminary)
EP1084
5A Low Dropout Linear Regulator
Features
Description
• Output current limiting
• Adjustable output voltage or fixed 1.5V, 1.8V,
2.5V, 3.3V, 5.0V
• Good noise rejection
• 1.4V maximum dropout at full load current
• Built-in thermal shutdown
• Fast transient response
• Packages: TO252, TO263
EP1084 is a low dropout positive adjustable or
fixed-mode regulator with minimum of 5.0A output
current capability. The product is specifically
designed to provide well-regulated supply for low
voltage IC applications such as high-speed bus
termination and low current 3.3V logic supply.
EP1084 is also well suited for other applications
such as VGA cards. EP1084 is guaranteed to
have lower than 1.4V dropout at full load current
making it ideal to provide well-regulated outputs
of 1.25 to 3.3V with 4.7 to 12V input supply.
Applications
• PC peripheral
• Low Voltage Logic Supplies
• Post Regulator for Switching Power Supply
Typical Application
Fixed Mode Regulator
5.0V to 2.5V Adjustable Regulator
⎛
⎝
VOUT= VREF × ⎜1 +
R2 ⎞
⎟
R1 ⎠
VREF =1.25V
R1≒100Ω~200Ω
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EP1084
Pin Assignment
Ordering Information
Pin Description
Pin
Name
Function
1
FB
(GND)
Adjustable (Ground only for fixed mode) A resistor divider from this pin to the
VOUT pin and ground sets the output voltage. (Ground only for Fixed-Mode)
2
VOUT
The output of the regulator. A minimum of 10uF (0.15Ω ≤ ESR ≤ 20Ω) capacitor
must be connected from this pin to ground to insure stability.
VIN
The input pin of regulator. Typically a large storage capacitor (0.15Ω≤ ESR ≤
20Ω) is connected from this pin to ground to insure that the input voltage does
not sag below the minimum dropout voltage during the load transient response.
This pin must always be 1.4V (1.3V) higher than VOUT in order for the device to
regulate properly.
3
Absolute Maximum Rating
Symbol
Item
VI
DC Supply Voltage
PD
Power Dissipation
Rating
(Note 2)
Units
15
V
Internally Limited
TSTG
Storage Temperature Range
TOP
Operating Junction Temperature Range
Jul. 2006
-65 ~ +150
°C
0 ~ +150
°C
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EP1084
Electrical Characteristics
(Under operating conditions)
Symbol
VREF
REGLINE
REGLOAD
VD
ILIMIT
Parameter
Reference Voltage
Conditions
TJ=25°C, IOUT=10mA,
(VIN -VOUT) =1.5V
Min.
Typ.
Max.
Units
1.225
1.250
1.275
V
0.2
%
EP1084-adj
TJ=25°C, IOUT=10mA,
VOUT +1.5V<VIN<12V
EP1084-15
TJ=25°C, IOUT=10mA,
3V≤VIN≤12V
1.470
1.500
1.530
EP1084-18
TJ=25°C, IOUT=10mA,
3.3V≤VIN≤12V
1.764
1.800
1.836
EP1084-25
TJ=25°C, IOUT=10mA,
4V≤VIN≤12V
2.450
2.500
2.550
EP1084-33
TJ=25°C, IOUT=10mA,
4.8V≤VIN≤12V
3.235
3.300
3.365
EP1084-50
TJ=25°C, IOUT=10mA,
6.5V≤VIN≤12V
4.900
5.000
5.100
EP1084-adj
TJ=25°C, VIN=3.3V,
(Note1, 2)
0mA<IOUT<5A
EP1084-15
TJ=25°C, VIN=3V,
(Note1, 2)
0mA<IOUT<5A
12
15
EP1084-18
TJ=25°C, VIN=3.3V,
(Note1, 2)
0mA<IOUT<5A
15
18
EP1084-25
TJ=25°C, VIN=4V,
(Note1, 2)
0mA<IOUT<5A
20
25
EP1084-33
TJ=25°C, VIN=5V,
(Note1, 2)
0mA<IOUT<5A
26
33
EP1084-50
TJ=25°C, VIN=8V,
(Note1, 2)
0mA<IOUT<5A
45
50
Dropout Voltage
IOUT=5A(∆VOUT=1%VOUT)
1.3
1.4
V
Current Limit
(VIN -VOUT)=5V
5
10
mA
Line
Regulation
Load
Regulation
IO
Minimum Load Current
TS
Temperature Stability
θJA
Thermal
Resistance
TO-252
θJC
Thermal
Resistance
TO-252
TO-263
TO-263
1
5.1
V
%
mV
A
IOUT=10mA
0.5
Junction-to-Ambient (No
heat sink ;No air flow)
98
Junction-to-Case
(Control circuitry/Power
transistor)
10
83
%
°C/W
°C/W
0.65/2.7
Note 1: See thermal regulation specifications for changes in output voltage due to heating effects. Line and
load regulation are measured at a constant junction temperature by low duty cycle pulse testing.
Load regulation is measured at the output lead = 1/18” from the package.
Note 2: Line and load regulation are guaranteed up to the maximum power dissipation of 15W. Power
dissipation is determined by the difference between input and output and the output current.
Guaranteed maximum power dissipation will not be available over the full input/output range.
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EP1084
Typical Performance Characteristics
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EP1084
Functional Block Diagram
VIN
VOUT
+
+
+
Current
Limit
Thermal
Shutdown
1.25V
FB
Introduction
The EP1084 adjustable Low Dropout (LDO) regulator is a 3 terminal device that can easily be
programmed with the addition of two external resistors to any voltages within the range of 1.25V to VIN
-1.4V. The EP1084 only needs 1.4V differential between VIN and VOUT to maintain output regulation. In
addition, the output voltage tolerances are also extremely tight and they include the transient response
as part of the specification. For example, Intel VRE specification calls for a total of ±100mV including
initial tolerance, load regulation and 0 to 5.0A load step.
The EP1084 is specifically designed to meet the fast current transient needs as well as providing an
accurate initial voltage, reducing the overall system cost with the need for fewer output capacitors.
Output Voltage Setting
The EP1084 can be programmed to any voltages in the range of 1.25V to VIN -1.4V with the addition of
R1 and R2 external resistors according to the following formula:
The EP1084 keeps a constant 1.25V between the output pin and the FB pin. By placing a resistor R1
across these two pins a constant current flows through R1, adding to the IFB current and into the R2
resistor producing a voltage equal to the (1.25/R1)*R2+IFB*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 EP1084 is 10mA, R1 is typically selected to be 121Ω resistor so that it automatically satisfies the
minimum current requirement. Notice that since IFB is typically in the range of 55uA 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 IFB is
only 0.3% of the nominal set point.
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EP1084
⎛
⎝
VOUT= VREF × ⎜1 +
R2 ⎞
⎟ +IFBR2
R1 ⎠
Load Regulation
Since the EP1084 is only a 3 terminal device, it is not possible to provide true remote sensing of the
output voltage at the load. The best load regulation is achieved when the bottom side of R2 is connected
to the load and the top-side of R1 resistor is connected directly to the case or the VOUT pin of the
regulator and not to the load. It is important to note that for high current applications, this can re-present
a significant percentage of the overall load regulation and one must keep the path from the regulator to
the load as short as possible to minimize this effect.
Stability
The EP1084 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 10uF aluminum electrolytic capacitor
insures both stability and good transient response.
Thermal Design
The EP1084 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°C, 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.
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.
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EP1084
Package Description
TO-252
D
b
L2
E
L1
b1
e
e1
A1
L
H
c
A
Seating Plane
DIM
MILLIMETERS
MIN.
NOM.
c1
INCHES
MAX.
MIN.
NOM.
MAX.
A
2.18
2.29
2.40
0.094
0.89
−
1.14
0.086
0.035
0.090
A1
−
0.045
b
5.20
5.35
5.50
0.205
0.211
0.217
b1
0.61 TYP.
0.024 TYP.
c
0.45
0.52
0.58
0.018
0.020
0.023
c1
0.45
0.52
0.58
0.018
0.020
0.023
D
6.35
6.58
6.80
0.250
0.259
0.268
E
5.40
5.57
6.20
0.213
0.219
0.244
e
2.28 REF.
e1
4.57 REF.
0.090 REF.
0.180 REF.
H
9.00
9.70
10.40
0.354
L
0.51
−
−
0.020
−
−
L1
0.64
0.83
1.02
0.025
0.033
0.040
L2
0.88
−
1.27
0.035
−
0.050
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0.409
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EP1084
Package Description (Continued)
TO-263
D
L2
E
L
L1
b
e
b1
A
c
c1
L3
DIM
MILLIMETERS
INCHES
MIN.
NOM.
MAX.
MIN.
NOM.
MAX.
A
4.06
4.45
4.83
0.160
0.175
0.190
b
0.51
0.75
0.99
0.020
0.030
0.039
b1
1.14
1.27
1.40
0.045
0.050
0.055
c
0.38 TYP.
0.015 TYP.
c1
1.14
1.27
1.40
0.045
0.050
0.055
D
9.65
9.97
10.29
0.380
0.393
0.405
E
8.65
9.15
9.65
0.341
0.360
0.380
e
2.54 BSC.
0.100 BSC.
L
14.61
15.24
15.88
0.575
0.600
0.625
L1
1.27
1.52
1.78
0.050
0.060
0.070
L2
−
1.30
2.92
−
0.051
0.115
L3
2.28
2.54
2.80
0.090
0.100
0.110
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