1.5A Ultra Low Dropout Positive Adjustable or Fixed-mode Regulator
Feature
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General Description
AP1186 is a 1.5A 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 a
switcher can be achieved without the cost and
complexity associated with switching regulator. One
such application is the new graphic chip sets that
require anywhere from 2.4V to 2.7V supply.
Adjustable or Fixed output voltage 1.5V, 1.8V,
2.5V, 3.3V, 5.0V
0.5V Maximum Dropout voltage at 1.5A Load
current
Built-in Thermal Shutdown
Output Current Limiting
Fast transient response
Good noise rejection
Package : TO220-5L, TO263-5L
Ordering Information
AP 1186 X X X X
Low Dropout Regulator
Package
Vout
Lead Free
Blank : Normal
L : Lead Free Package
Packing
Blank : Tube
A : Taping& Reel
K5:TO-263-5L Blank : Adj
T5:TO-220-5L 15 : 1.5V
18 : 1.8V
25 : 2.5V
33 : 3.3V
50 : 5.0V
Typical Application
3V
+
470uF
+
Vin
Vctrl
Vout
GND
Vsense
5
4
3
2
1
5V
470uF
2.5V/1.5A
+
470uF
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
1/8
AP1186
1.5A Ultra Low Dropout Positive Adjustable or Fixed-mode Regulator
Block Diagram
Vin
Vctrl
+
+
CURRENT
LIMIT
THERMAL
SHUTDOWN
-
1.25V
+
-
Adj
+
Vout
Vsense
Package Connect Diagram
5 PIN TO263
FRONT VIEW
5
4
3
2
1
Tab is Vout
Vin
Vctrl
Vout
Adj(GND)
Vsense
5 PIN TO220
FRONT VIEW
5
4
3
2
1
Tab is Vout
Vin
Vctrl
Vout
Adj(GND)
Vsense
Pin Descriptions
Name
Adj
(GND)
Vsense
I/O
Description
A resistor divider from this pin to the Vout pin and ground sets the output voltage.
(GND only for fixed mode)
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.
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.
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.
Not used.
The output of the regulator. A minimum of 100uF capacitor must be connected from
this pin to ground to insure stability.
I
Vin
I
Vctrl
NC
Vout
I
O
Anachip Corp.
www.anachip.com.tw
2/8
Rev.1.1 Sep.7, 2004
AP1186
1.5A Ultra Low Dropout Positive Adjustable or Fixed-mode Regulator
Absolute Maximum Ratings
Symbol
Vin
Vctrl
PD
T
ST
T
OP
Parameter
Input Voltage
Control Input Voltage
Power Dissipation
Storage Temperature
Operating Junction Temperature Range
Rating
16
18
Internally Limited
-65 to +150
0 to +150
Unit
V
V
oC
oC
Electrical Characteristics
Unless otherwise specified, these specifications apply over, Cin=1uF, Cout=10uF, and Tj=0 to 150 C. Typical value refer to Tj=25 C.
Vout = Vsense.
o
o
SYM.
V
REF
V
out
Test Condition
T
J
=25
o
C,(V
IN
-V
OUT
)=0.5V,I
O
=10mA
Reference Voltage AP1186-Adj
V
ctrl
=V
IN
+1V
I
OUT
= 10mA, T
J
= 25
o
C, 2V≦V
IN
≦12V
AP1186-1.5
V
ctrl
=V
IN
+1V
I
OUT
= 10mA, T
J
= 25
o
C, 2.3V≦V
IN
≦12V
AP1186-1.8
V
ctrl
=V
IN
+1V
I
OUT
= 10mA, T
J
= 25
o
C, 3V≦V
IN
≦12V
Output Voltage
AP1186-2.5
V
ctrl
=V
IN
+1V
I
OUT
= 10mA, T
J
= 25
o
C, 3.8V≦V
IN
≦12V
AP1186-3.3
V
ctrl
=V
IN
+1V
I
OUT
= 10mA, T
J
= 25
o
C, 5.5V≦V
IN
≦12V
AP1186-5.0
V
ctrl
=V
IN
+1V
I =10mA, V
OUT
+0.5V<V
IN
<12V
Line Regulation
AP1186-XXX
O
V
ctrl
=V
IN
+1V
0mA<Io<1.5A, T
J
=25
o
C
AP1186-Adj
(V
IN
– V
OUT
) = 2V, V
ctrl
= V
IN
+ 1V
o
V
IN
=3V, 0mA<Io<1.5A, T
J
=25 C
AP1186-1.5
V
ctrl
=4V
V
IN
=3.3V, 0mA<Io<1.5A, T
J
=25
o
C
AP1186-1.8
V
ctrl
=4.3V
Load Regulation
V
IN
=4V, 0mA<Io<1.5A, T
J
=25
o
C
AP1186-2.5
V
ctrl
=5V
V
IN
= 5V, 0≦I
OUT
≦1.5A,
T
J
=25
o
C ,
AP1186-3.3
T
J
=25
o
C V
ctrl
=6V
V
IN
= 8V, 0≦I
OUT
≦1.5A,
T
J
=25
o
C ,
AP1186-5.0
o
T
J
=25 C V
ctrl
=9V
Dropout Voltage
Vadj=0V for all conditions below.
(Vctrl-Vout)
Vin=2.05V, Io=1.5A
Dropout Voltage
Vadj=0V for all conditions below.
(Vin-Vout)
Vctrl=3V, Io=1.5A
Current Limit
Vctrl=3V, Vin=2.05V,
∆Vo=100mV,
Vadj=0V
Minimum Load
Vctrl=5V, Vin=3.3V, Vadj=0V
Current
Parameter
Min.
Typ. Max. Unit
V
1.225 1.250 1.275
1.470 1.500 1.530
1.764 1.800 1.836
2.450 2.500 2.550
3.235 3.300 3.365
4.900 5.000 5.100
0.2
1
12
15
20
26
40
15
18
25
33
50
1.23
0.26
1.6
5
10
0.38
V
%
%
mV
mV
mV
mV
mV
V
V
A
mA
Anachip Corp.
www.anachip.com.tw
3/8
Rev.1.1 Sep.7, 2004
AP1186
1.5A Ultra Low Dropout Positive Adjustable or Fixed-mode Regulator
Electrical Characteristics
Unless otherwise specified, these specifications apply over, Cin=1uF, Cout=10uF, and Tj=0 to 150 C. Typical value refer to Tj=25 C.
Vout = Vsense.
o
o
SYM.
Parameter
Thermal
Regulation
Ripple Rejection
Test Condition
30ms Pulse
Min.
Typ. Max. Unit
0.01
0.02
%W
dB
25
150
o
Vctrl =5V, Vin=5V, Io=1.5A, Vadj=0V, Tj=25,
Vripple=1Vpp at 120Hz
Control Pin
Vadj=0V for all conditions below.
Current
Vctrl=2.75V, Vin=2.05V, Io=1.5A
Iadj Adjust Pin Current Vctrl=2.75V, Vin=2.05,Vadj=0
Thermal
TO-263: Control Circuitry/Power Transistor
Θ
JC
Resistance
TO-220: Control Circuitry/Power Transistor
Junction-to-Case
60
70
6
50
2.5
2.5
mA
µA
C/W
NOTE:
AP1186-ADJ incorporates an internal thermal shutdown that protects the device when the junction temperature exceeds the allowable
maximum junction temperature.
Package
Max Pd.
TO-263/TO-220 2.4W~4.4W
With heat sink or amount of copper board needed.
Functional Descriptions
Introduction
The AP1186 regulator is a 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 AP1186 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 AP1186-ADJ 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 AP1186 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 AP1186-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:
Anachip Corp.
www.anachip.com.tw
4/8
Rev.1.1 Sep.7, 2004
AP1186
1.5A Ultra Low Dropout Positive Adjustable or Fixed-mode Regulator
Functional Descriptions(Continued)
Vout = Vref (1+R2/R1) + Iadj * R2 where : Vref = 1.25V & Iadj=50uA Typically
Vin
AP1186-ADJ
Vctrl
Adj
Iadj=50uA
Vsense
Vref
R1+
Vout
R2+
The AP1186-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
AP1186-ADJ is 10mA, R1 is typically selected to be
a 121Ω 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 AP1186 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 AP1186 with remote
sensing.
Vin
Vin
AP1186-ADJ
Vout
Vsense
R1
R2
R
L
Vctrl
Vctrl
Adj
Stability
The AP1186-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 100mΩ and an output capacitance of
100uF to 1000uF. Fortunately as the capacitance
increases, the ESR decreases resulting in a fixed
RC time constant. The AP1186-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
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