4A Ultra Low Dropout Positive Adjustable or Fixed-mode Regulator
AP1184
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.1.1 Sep 7, 2004
1/11
Feature
0.7V maximum dropout voltage at 4A load current
Built-in Thermal shutdown
Output current limiting
Adjustable or fixed output voltage
1.5V, 1.8V, 2.5V, 3.3V, 5.0V
Fast transient response
Good noise rejection
Packages: SOP-7L, TO220-5L and TO263-5L
General Description
AP1184 is a 4A regulator with extremely low
dropout voltage. This product is specifically
designed to provide well regulated supply for
applications requiring 2.8V or lower voltages from
3.3V ATX power supplies where high efficiency of
the switch can be achieved without the cost and
complexity associated with switching regulator. One
such application is the new graphic chipsets that
requires anywhere from 2.4V to 2.7V supply.
Ordering Information
AP1184 X X X X
Low Dropout Regulator
Package
Vout
S7:SOP-7L
K5:TO263-5L
T5:TO220-5L
Blank : Adj
15 = 1.5V
18 = 1.8V
25 = 2.5V
33 = 3.3V
50 = 5.0V
Packing
Blank : Tube
A : Taping
Lead Free
Blank : Normal
L : Lead Free Package
Typical Application
470uF
+
470uF
+
5V
470uF
+
3.3V
2.5V/4A
GND
Vsense
Vin
Vctrl
Vin
Vout
Vout
NC
AP1184-2.5V
4A Ultra Low Dropout Positive Adjustable or Fixed-mode Regulator
AP1184
Anachip Corp.
www.anachip.com.tw
Rev.1.1 Sep 7, 2004
2/11
Block Diagram
THERMAL
SHUTDOWN
Vout
Adj
1.25V
+
CURRENT
LIMIT
Vin
+
-
+
+
-
Vsense
Vctrl
Pin Configuration
(AP1184K5)
(AP1184T5)
Tab is Vout
FRONT VIEW
3
2
1
Vout
Vsense
Adj(GND)
Vctrl
Vin
4
5
Tab is Vout
FRONT VIEW
Vout
Vsense
Adj(GND)
Vctrl
Vin
5
2
1
4
3
( AP1184S7 )
Adj(GND)
Vsense
Vin
Vctrl
Vin
Vout
NC
7
6
5
8
2
3
4
1
Pin Descriptions
Pin Numbers with standard type are for TO220-5L, TO263-5L packages, and those with boldface type are for SOP-7L
Name
I/O
Description
Adj
(GND)
A resistor divider from this pin to the Vout pin and ground sets the output voltage.
(GND only for fixed mode)
Vsense I
This pin is the positive side of the reference that allows remote load sensing to
achieve excellent load regulation. A minimum of 10uF capacitor must be connected
from this pin to ground to insure stability.
Vin I
The input of the regulator. Typically a large storage capacitor 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 higher
than Vout in order for the device to regulate.
Vctrl I
This pin is the supply pin for the internal control circuit as well as the base drive for
the pass transistor. This pin must always by higher than the Vout pin in order the
device to regulate. A minimum of 100uF capacitor must be connected from this pin to
ground to insure stability.
NC
No
connection
Vout O
The output of the regulator. A minimum of 100uF capacitor must be connected from
this pin to ground to insure stability.
4A Ultra Low Dropout Positive Adjustable or Fixed-mode Regulator
AP1184
Anachip Corp.
www.anachip.com.tw
Rev.1.1 Sep 7, 2004
3/11
Absolute Maximum Ratings
Symbol
Parameter
Rating
Unit
V
IN
Input
Voltage
16
V
V
ctrl
Control Input voltage
18
V
P
D
Power
dissipation
Internally limited
T
ST
Storage temperature Range
-65 to +150
o
C
T
OP
Operation Junction Temperature Range
0 to +150
o
C
Electrical Characteristics
Unless otherwise specified, these specifications apply over, Cin=1uF, Cout=10uF, and Tj=0 to 150
o
C. Typical value refer to Tj=25
o
C.
Vout=Vsense.
Sym.
Parameter
Test Condition
Min. Typ. Max. Unit
V
REF
Reference Voltage AP1184-Adj
Io=10mA, Tj=25
o
C, (Vin-Vout)=0.7V,
V
ctrl
=V
IN
+1V
1.225 1.250 1.275
V
Line
Regulation AP1184-XXX
I
O
=10mA, V
OUT
+0.7V<V
IN
<12V, T
J
=25
o
C
V
ctrl
=V
IN
+1V
0.2
%
AP1184-1.5
I
OUT
= 10mA, T
J
= 25
o
C, 2.2VV
IN
12V
V
ctrl
=V
IN
+1V
1.470 1.500 1.530
V
AP1184-1.8
I
OUT
= 10mA, T
J
= 25
o
C, 2.5VV
IN
12V
V
ctrl
=V
IN
+1V
1.764 1.800 1.836
V
AP1184-2.5
I
OUT
= 10mA, T
J
= 25
o
C, 3.2VV
IN
12V
V
ctrl
=V
IN
+1V
2.450 2.500 2.550
V
AP1184-3.3
I
OUT
= 10mA, T
J
= 25
o
C, 4.0VV
IN
12V
V
ctrl
=V
IN
+1V
3.235 3.300 3.365
V
V
out
Output
Voltage
AP1184-5.0
I
OUT
= 10mA, T
J
= 25
o
C, 5.7VV
IN
12V
V
ctrl
=V
IN
+1V
4.900 5.000 5.100
V
AP1184-Adj
0mA<Io<4A, T
J
=25
o
C
(V
IN
- V
OUT
)=2V ,V
ctrl
=V
IN
+ 1V
1
%
AP1184-1.5
V
IN
=3V, 0mA<Io<4A, T
J
=25
o
C
V
ctrl
=4V
12 15
mV
AP1184-1.8
V
IN
=3.3V, 0mA<Io<4A, T
J
=25
o
C
V
ctrl
=4.3V
15 18
mV
AP1184-2.5
V
IN
=4V, 0mA<Io<4A, T
J
=25
o
C
V
ctrl
=5V
20 25
mV
AP1184-3.3
V
IN
= 5V, 0mA<Io<4A, T
J
=25
o
C
V
ctrl
=6V
26 33
mV
Load
Regulation
AP1184-5.0
V
IN
= 8V, 0mA<Io<4A, T
J
=25
o
C
V
ctrl
=9V
40 50
mV
Dropout Voltage
(Vctrl Vout)
Vadj=0V for all conditions below.
Vin=2.05V, Io=1.5A
Vin=2.05V, Io=3A
Vin=2.05V, Io=4A
1.10
1.15
1.18
1.25
V
Dropout Voltage
(Vin -Vout)
Vadj=0V for all conditions below.
V
ctrl
=2.75V, Io=1.5A
V
ctrl
=2.75V, Io=3A
V
ctrl
=2.75V, Io=4A
0.26
0.50
0.70
0.38
0.60
0.85
V
Current
Limit
V
ctrl
=2.75V, Vin=2.05V,
Vo=100mV, Vadj=0V
4.2 A
Minimum Load
Current
V
ctrl
=5V, Vin=3.3V, Vadj=0V
5
10
mA
4A Ultra Low Dropout Positive Adjustable or Fixed-mode Regulator
AP1184
Anachip Corp.
www.anachip.com.tw
Rev.1.1 Sep 7, 2004
4/11
Electrical Characteristics(Continued)
Unless otherwise specified, these specifications apply over, Cin=1uF, Cout=10uF, and Tj=0 to 150
o
C. Typical value refer to Tj=25
o
C.
Vout=Vsense.
Sym.
Parameter
Test Condition
Min. Typ. Max. Unit
Thermal
Regulation
30mS
Pulse
0.01 0.02
%/W
Ripple
Rejection
V
ctrl
=5V, Vin=5V, Io=4A, Vadj=0V, Tj=25, Vripple=1Vpp at
120Hz
60 70 dB
Control
Pin
Current
Vadj=0V for all conditions below.
V
ctrl
=2.75V, Vin=2.05V, Io=1.5A
V
ctrl
=2.75V, Vin=2.05V, Io=3A
Vctrl=2.75V, Vin=2.05V, Io=4A
6
30
33
25
60
70
mA
Iadj Adjust Pin Current Vctrl=2.75V, Vin=2.05,Vadj=0
50
150
A
JC
Thermal Resistance
Junction-to-Case
TO-263: Control Circuitry/Power Transistor
TO-220: Control Circuitry/Power Transistor
SOP-7: Control Circuitry/Power Transistor
3.5
2.5
20
O
C/W
O
C/W
O
C/W
NOTE:
AP1184-ADJ incorporates an internal thermal shutdown that protects the device when the junction temperature exceeds the allowable
maximum junction temperature.
Package
Max Pd.
Remarks
TO263/TO220
2.4W~4.4W With heat sink or amount of copper board needed.
SOP7
1W~2W
With heat sink or amount of copper board needed.
Functional Descriptions
Introduction
The AP1184 regulator is 5 terminal device designed
specifically to provide extremely low dropout
voltages comparable to the PNP type without the
disadvantage of the extra power dissipation due to
the base current associated with PNP regulators.
This is done by bringing out the control pin of the
regulator that provides the base current to the
power NPN and connecting it to a voltage that is
greater than the voltage present at the Vin pin. This
flexibility makes the AP1184 ideal for applications
where dual inputs are available such as a computer
motherboard with an ATX style power supply that
provides 5V and 3.3V to the board. One such
application is the new graphic chip sets that require
anywhere from 2.4V to 2.7V supply. The AP1184
can easily be programmed with the addition of two
external resistors to any voltages within the range
of 1.25V to 15.5V. Another major requirement of
these graphic chips is the need to switch the load
current from zero to several amps in tens of
nanoseconds at the processor pins, which
translates to an approximately 300 to 500ns of
current step at the regulator. In addition, the output
voltage tolerances are also extremely tight and they
include the transient response as part of the
specification.
The AP1184 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 number of output
capacitors. Another feature of the device is its true
remote sensing capability that allows accurate
voltage setting at the load rather than at the device.
Output Voltage Setting
The AP1184-ADJ can be programmed to any
voltages in the range of 1.25V to 15.5V with the
addition of R1 and R2 external resistors according
to the following formula:
4A Ultra Low Dropout Positive Adjustable or Fixed-mode Regulator
AP1184
Anachip Corp.
www.anachip.com.tw
Rev.1.1 Sep 7, 2004
5/11
Functional Descriptions(Continued)
Vout = Vref (1+R2/R1) + Iadj * R2 where : Vref = 1.25V & Iadj=50uA Typically
AP1184-ADJ
Vin
Vctrl
Adj
Vout
Vsense
R1+
R2+
Vref
Iadj=50uA
The AP1184-ADJ keeps a constant 1.25V between
the Vsense pin and the Adj pin. By placing a
resistor R1 across these two pins and connecting
the Vsense ans Vout pin together, 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. This voltage is then
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
AP1184-ADJ is 10mA, R1 is typically selected to be
a 121 resistor so that it automatically satisfies
this condition. Notice that since the Iadj is typically
in the range of 50uA it only adds a small error to the
output voltage and should be considered when very
precise output voltage setting is required.
Load Regulation
Since the AP1184 has separate pins for the output
(Vout) and the sense (Vsense), it is ideal for
providing true remote sensing of the output voltage
at the load. This means that the voltage drops due
to parasitic resistance such as PCB traces between
the regulator and the load are compensated for
using remote sensing. Figure following shows a
typical application of the AP1184-ADJ with remote
sensing.
AP1184-ADJ
Vin
Vctrl
Vin
Vctrl
Vout
Vsense
Adj
R1
R2
R
L
Stability
The AP1184-XXX requires the use of an output
capacitor as part of the frequency compensation in
order to make the regulator stable. Typical designs
for the microprocessor applications use standard
electrolytic capacitors with typical ESR in the range
of 50 to 100m and an output capacitance of
100uF to 1000uF. Fortunately as the capacitance
increases, the ESR decreases resulting in a fixed
RC time constant. The AP1184-XXX takes
advantage of the phenomena in making the overall
regulator loop stable. For most applications a
minimum of 100uF aluminum electrolytic capacitor
insures both stability and good transient response.
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