CYStech Electronics Corp.
5A Low Dropout Positive Voltage Regulator
Spec. No. : C547F3
Issued Date : 2007.09.26
Revised Date
Page No. : 1/6
PL1084A-XXXF3
Features
Maximum
Dropout Voltage 1.65V at 5A Output Current.
Fast Transient Response.
Extremely Tight Line and Load Regulation.
Current Limiting and Thermal Protection.
Adjustable Output Voltage or Fixed 1.5V, 1.8V,2.5V,3.3V,5.0V.
Standard 3-Pin Power Packa
ges.
TO-263
Description
The PL1084A-XXXF3 is a low dropout three terminal regulator with 5A output current capability. The output voltage is
adjustable with the use of a resistor divider or fixed 1.5V, 1.8V, 2.5V, 3.3V, and 5.0V. Dropout voltage is guaranteed to be at
maximum of 1.5V with the maximum output current. Its low dropout voltage and fast transient response make it ideal for
low voltage microprocessor applications. Current limit and thermal protection provide protection against any overload
condition that would create excessive junction temperatures.
Applications
Mother Board I/O Power Supplies.
Microprocessor Power Supplies.
High Current Regulator.
Post Regulator for Switching Supply.
Typical Application Circuit
Vin=5V
3
Vout=3.3V
2
PL1084A-Adj
VREF
1
C1
10μF
ADJ
R1
125Ω
1%
R2
205Ω
1%
C2
10μF
Adjustable Voltage Regulator
Vin=5V
3
2
Vout=3.3V
PL1084A-3.3
C1
10μF
C2
10μF
1
Fixed Voltage Regulator
PL1084A-XXXF3
CYStek Product Specification
CYStech Electronics Corp.
Ordering Information
Device
PL1084A-AdjF3
PL1084A-1.5F3
PL1084A-1.8F3
PL1084A-2.5F3
PL1084A-3.3F3
PL1084A-5.0F3
Output Voltage
Adjustable
1.5V
1.8V
2.5V
3.3V
5.0V
Spec. No. : C547F3
Issued Date : 2007.09.26
Revised Date
Page No. : 2/6
Absolute Maximum Ratings
Symbol
Vin
P
D
T
STG
T
OPR
Parameter
DC supply voltage
Power Dissipation
Storage Temperature
Operating Junction Temperature
Ratings
Unit
-0.3 to +12
V
Internally Limited
-65 ~ +150
℃
0 ~ +150
℃
Electrical Characteristics
(Io=10mA,Tj=25℃, unless otherwise noted)
Symbol
V
REF
Parameter
Reference Voltage
Output Voltage
Conditions
Min
1.225
1.470
1.764
2.450
3.235
4.900
-
-
-
-
-
-
-
-
-
5.1
-
-
-
-
-
-
Typ
1.250
1.500
1.800
2.500
3.300
5.000
-
-
12
15
20
26
40
1.18
1.25
1.55
-
55
-
0.5
5
91
10
Max
1.275
1.530
1.836
2.550
3.365
5.100
0.2
1
15
18
25
33
50
1.25
1.30
1.65
-
100
12
-
10
-
-
Units
V
Vin-Vout=1.5V
PL1084A-1.5 3V≤Vin≤12V
PL1084A-1.8 3.3V≤Vin≤12V
PL1084A-2.5 4V≤Vin≤12V
PL1084A-3.3 4.8V≤Vin≤12V
PL1084A-5.0 6.5V≤Vin≤12V
Line Regulation
Fixed: Vout+1.5V≤Vin≤12V
Adj
Vin=3.3V, 0≤Io≤5A
PL1084A-1.5 Vin=3.0V, 0≤Io≤5A
PL1084A-1.8 Vin=3.3V, 0≤Io≤5A
Load Regulation(Note 1, 2)
PL1084A-2.5 Vin=4.0V, 0≤Io≤5A
PL1084A-3.3 Vin=5.0V, 0≤Io≤5A
PL1084A-5.0 Vin=8.0V, 0≤Io≤5A
Dropout Voltage
Current Limit
Adjust Pin Current
Quiescent Current
Temperature Stability
Minimum Load Current
Thermal Resistance,
Junction to Ambient(No
Heat Sink; No air flow)
Io=1A (ΔVout=1%V
out
)
Io=2A (ΔVout=1%V
out
)
Io=5A (ΔVout=1%V
out
)
Vin-Vout=5V
Vin=12V, Io=10mA
Vin=12V, Io=0mA(fixed model)
Io=10mA, 0°C≤Tj≤125°C
Vin=5V(adjustable model)
Vo
ΔVo
V
%
%
ΔVo
mV
V
D
Is
I
Adj
I
Q
Ts
I
L
θ
JA
θ
JC
V
A
μ
A
mA
%
mA
℃
/W
℃
/W
Thermal Resistance,
Junction to Case
PL1084A-XXXF3
CYStek Product Specification
CYStech Electronics Corp.
Spec. No. : C547F3
Issued Date : 2007.09.26
Revised Date
Page No. : 3/6
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.
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
over the full input/output range.
Block Diagram
Functional Description
Introduction
The PL1084A 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 2.5V. The PL1084A only needs 1.5V
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 5A load step. The
PL1084A 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 PL1084A can be programmed to any voltages in the range of 1.25V to 5V with the addition of R1 and R2
external resistors according to the following formula:
Vout=Vref(1+R2/R1)+Iadj*R2, where Vref=1.25V typically, Iadj=55μA typically
The PL1084A 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 requirement of the PL1084A. 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 55μA, 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.
PL1084A-XXXF3
CYStek Product Specification
CYStech Electronics Corp.
Load Regulation
Spec. No. : C547F3
Issued Date : 2007.09.26
Revised Date
Page No. : 4/6
Since the PL1084A is only a 3 terminal device, it is not possible to provide true remote sensing of 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 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 represent 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 PL1084A 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 10μF aluminum electrolytic capacitor insures both stability
and good transient response.
Thermal Design
The PL1084A incorporates an internal 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.
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 excess trace inductance.
PL1084A-XXXF3
CYStek Product Specification
CYStech Electronics Corp.
Characteristic Curves
Spec. No. : C547F3
Issued Date : 2007.09.26
Revised Date
Page No. : 5/6
PL1084A-XXXF3
CYStek Product Specification
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