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. AP033 is
guaranteed to have <1.4V dropout at full load
current making it ideal to provide well regulated
outputs of 3.3V with 4.7V to 12V input supply by
different output voltage.
3-Terminal and Fixed 3.3V
1.4V Maximum Dropout at Full Load Current.
Fast Transient Response.
Built-in Thermal Shutdown.
Output Current Limiting.
Applications
•
•
PC peripheral
Communication
Ordering Information
AP 033 X X X
LDO Regulator
033 Vout = 3.3V
Package
Lead Free
Packing
Blank : Tube
A : Taping
D : TO252-3L Blank : Normal
L : Lead Free Package
Pin Assignments
3 PIN TO252
3
2
1
Tab is GND
V
OUT
GND
V
IN
Pin Descriptions
Name
Pin #
Function
The input pin of 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 1.4V higher than V
OUT
in
order for the device to regulate
properly.
Ground
The output of the regulator. A
minimum of 10µF capacitor
must be connected from this pin
to ground to insure stability.
Ground
V
IN
1
GND
V
OUT
2
3
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.1.0 Aug.27, 2004
1/5
AP033
1.5A Low Dropout Positive Fixed-Mode Regulator
Block Diagram
Vin
1
3
Vout
+
+
－
CURRENT
LIMIT
+
THERMAL
SHUTDOWN
2
GND
－
1.25V
+
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 14
V
Internally Limited
o
-65 to +150
C
o
0 to +150
C
Electrical Characteristics
(Under Operating Conditions)
Parameter
Output Voltage
Line Regulation
Load Regulation
Dropout Voltage
(V
IN
-V
OUT
)
Current Limit
Quiescent Current
Thermal Regulation
Ripple Rejection
Temperature Stability
Thermal Resistance
Junction-to-Ambient
(No heat sink ;No air
flow)
Thermal Resistance
Junction-to-Case
Conditions
V
IN
= 5V, I
OUT
= 0mA, T
J
= 25
o
C
4.7V<V
IN
<12V, 0<I
OUT
<1.5A
4.7V<V
IN
<12V, I
OUT
= 0mA, T
J
=25
o
C
V
IN
= 5V, 0<I
OUT
<1.5A, T
J
=25
o
C (Notes1.2)
∆V
OUT
,
∆V
REF
= 1%, I
OUT
=1.5A (Note 3)
(V
IN
-V
OUT
)>1.4V,
∆V
OUT
=100mV (Note 4)
V
IN
<12V
T
A
=25
o
C, 30ms pulse
F=120Hz, C
OUT
=25uF Tantalum, I
OUT
=1.5A
AP033
V
IN
=6.3V
1.6
5
10
0.008 0.04
60
0.5
101
10
o
Min. Typ. Max. Units
3.267 3.300 3.333
V
3.235 3.300 3.365
V
0.5
10
mV
1.0
10
mV
3
15
mV
8
33
mV
1.3
1.4
V
A
mA
%/W
dB
%
o
72
TO-252
TO-252: Control Circuitry/Power Transistor
C/W
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.
Note 2: Line and load regulation are guaranteed up to the maximum power dissipation of 2W. Power dissipation is determined by the
input/output differential and the output current.
Note 3: Dropout voltage is specified over the full output current range of the device.
Note 4: AP033 is guaranteed to operate at higher peak current than 1.6 Amp. See the thermal regulation specifications for changes in
output voltage due the heating effects.
Anachip Corp.
www.anachip.com.tw
2/5
Rev.1.0 Aug.27, 2004
AP033
1.5A Low Dropout Positive Fixed-Mode Regulator
Typical Application
5V
V
OUT
AP033
C2
100uF
GND
C1
100uF
V
IN
3.3V/
1.5A
Tab is GND
5V to 3.3V Fixed Mode Regulator
Function Description
Introduction
The AP033 fixed-mode Low Dropout (LDO)
regulator is a 3 terminal device. The AP033 only
needs 1.4V differential between V
IN
and V
OUT
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 1.5A load step.
The AP033 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.
Load Regulation
Since the AP033 is only a 3 terminal device, it is not
possible to provide true remote sensing of the
output voltage at the load. But it can supply good
load regulation by internal feedback bypass the
external loss such as adjustable mode.
Stability
The AP033 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 AP033 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
o
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 V
OUT
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 V
OUT
pin to the
output capacitors to prevent any high frequency
oscillation that may result due to excessive trace
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