5A Low Dropout Positive Adjustable or Fixed-Mode Regulator
Features
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General Description
AP1084 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. AP1084 is also well
suited for other applications such as VGA cards.
AP1084 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.
1.4V maximum dropout at full load current
Built-in thermal shutdown
Output current limiting
Adjustable output voltage or fixed 1.5V, 1.8V, 2.5V,
3.3V, 5.0V
Fast transient response
Good noise rejection
Package: TO252, TO263, TO220, PDIP-8
Ordering Information
AP1084 X
X
X
X
Low Dropout Regulator
Package
D : TO252-3L
K : TO263-3L
T : TO220-3L
N : PDIP-8L
Vout
Blank : Adj
15 = 1.5V
18 = 1.8V
25 = 2.5V
33 = 3.3V
50 = 5.0V
Lead Free
Packing
Blank : Normal
Blank : Tube
L : Lead Free Package A : Taping
Block Diagram
Vin
3
2 Vout
+
+
－
1.25V
CURRENT
LIMIT
+
Thermal
Shutdown
1
Adj
－
+
This datasheet contains new product information. Anachip Corp. reserves the rights to modify the product specification without notice. No liability is assumed as a result of the use of
this product. No rights under any patent accompany the sale of the product.
Rev.1.2 Jun.9, 2005
1/11
AP1084
5A Low Dropout Positive Adjustable or Fixed-Mode Regulator
Connection Diagram
TO263
FRONT VIEW
3
2
1
Tab is Vout
TO220
FRONT VIEW
3
2
1
Tab is Vout
Vin
Vout
Adj (GND)
Adj(GND) 1
Vout 2
Vout 3
Vin 4
AP1084
Vout
Adj (GND)
Vin
TO252
FRONT VIEW
3
2
1
Tab is Vout
PDIP-8
TOP VIEW
8
7
6
5
Vout
Vout
Vout
Vout
Vin
Vout
Adj (GND)
Pin Descriptions
Name
Adj
(GND)
Vout
I/O
Pin No.
TO263/
PDIP-8
252/220
1
2
1
2/3/5/6/
7/8
Function
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)
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.
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.
I
O
Vin
I
3
4
Anachip Corp.
www.anachip.com.tw
2/11
Rev.1.2
Jun.9, 2005
AP1084
5A Low Dropout Positive Adjustable or Fixed-Mode Regulator
Absolute Maximum Ratings
Symbol
Vin
P
D
T
ST
T
OP
Parameter
DC Supply Voltage
Power Dissipation
Storage Temperature
Operating Junction Temperature Range
Rating
Unit
-0.3 to 12
V
Internally Limited
oC
-65 to +150
oC
0 to +150
Electrical Characteristics
Sym.
V
REF
(Under Operating Conditions)
Min.
1.225
1.470
1.764
2.450
3.235
4.900
Parameter
Conditions (Notes)
Io=10mA, Tj=25
o
C, (Vin-Vout)=1.5V
I
O
=10mA, V
OUT
+1.5V<V
IN
<12V, T
J
=25
o
C
I
OUT
= 10mA, T
J
= 25
o
C, 3V≦V
IN
≦12V
I
OUT
= 10mA, T
J
= 25
o
C, 3.3V≦V
IN
≦12V
I
OUT
= 10mA, T
J
= 25
o
C, 4V≦V
IN
≦12V
I
OUT
= 10mA, T
J
= 25
o
C, 4.8V≦V
IN
≦12V
I
OUT
= 10mA, T
J
= 25
o
C, 6.5V≦V
IN
≦12V
V
IN
=3.3V, 0mA<Io<5A, T
J
=25
o
C
(Note 1,2)
V
IN
=3V, 0mA<Io<5A, T
J
=25
o
C
(Note 1,2)
V
IN
=3.3V, 0mA<Io<5A
T
J
=25
o
C (Note 1,2)
V
IN
=4V, 0mA<Io<5A
T
J
=25
o
C (Note 1,2)
V
IN
= 5V, 0mA<Io<5A , T
J
=25
o
C (Note 1,2)
V
IN
= 8V, 0mA<Io<5A, T
J
=25
o
C (Note 1,2)
Io=5.0A (∆Vout = 1% Vout)
Vin-Vout=5V
Typ.
1.250
1.500
1.800
2.500
3.300
5.000
Max.
1.275
0.2
1.530
1.836
2.550
3.365
5.100
1
Unit
V
%
V
V
V
V
V
%
mV
mV
mV
mV
mV
V
A
mA
%
Reference Voltage
AP1084-XXX
AP1084-1.5
AP1084-1.8
Line
Regulation AP1084-2.5
AP1084-3.3
AP1084-5.0
AP1084-Adj
AP1084-1.5
Load
AP1084-1.8
Regulation
AP1084-2.5
AP1084-3.3
AP1084-5.0
Dropout Voltage
Current Limit
Minimum Load
Current
Temperature
Stability
Thermal Resistance
Junction-to-Ambient
(No heat sink ;No
air flow)
Thermal Resistance
Junction-to-Ambient
12
15
20
26
40
1.3
5.1
5
15
18
25
33
50
1.4
10
∆Vo
Io=10mA
TO-252
TO-263
TO-220
0.5
98
83
83
35
10
0.65/2.7
0.65/2.7
O
θ
JA
O
C/W
θ
JC
PDIP-8: Control Circuitry/Power Transistor
(Note 3)
TO-252: Control Circuitry/Power Transistor
Thermal Resistance
TO-263: Control Circuitry/Power Transistor
Junction-to-Case
TO-220: Control Circuitry/Power Transistor
C/W
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.
Note 3:
Output is connected to the PCB cupper area 5.5mm*5.5mm separately. If you need large PD or lower Tc & Tj, please connect to
the large cupper area >> 5.5mm*5.5mm (like 10mm*10mm).
Anachip Corp.
www.anachip.com.tw
3/11
Rev.1.2
Jun.9, 2005
AP1084
5A Low Dropout Positive Adjustable or Fixed-Mode Regulator
Typical Circuit
(1) TO263/252/220
5.0V to 3.3V Fixed Mode Regulator
5V
5V
C1
100uF
Vin
Vout
GND
Tab is Vout
3.3V/5A
C2
100uF
Vin
Vout
Adj
Tab is Vout
R1 121
Ω
R2 121
Ω
C2
100uF
2.5V/5A
Adjustable Regulator
C1
100uF
Note: V
O
=
V
REF
∗
(1
+
R
2
R
1
)
(2) PDIP-8
5V/3.3V fixed output
5V
C1
100uF
Vout
Vin
3.3V/1A
C2
100uF
Vout
Vin
V
o
R1
121
Ω
R2
121
Ω
R
2
R
1
)
2.5V/1A
5V/2.5V Adj output
5V
C1
100uF
Vout Vout
Vout Vout
Vout GND
Tab is Vout
Vout Vout
Vout Vout
Vout Adj
Tab is Vout
C2
100uF
Note: V
O
=
V
REF
∗
(1
+
Anachip Corp.
www.anachip.com.tw
4/11
Rev.1.2
Jun.9, 2005
AP1084
5A Low Dropout Positive Adjustable or Fixed-Mode Regulator
Functional Description
Introduction
The AP1084 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
AP1084 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 AP1084 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 AP1084 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
