AP1503
300Khz, 2.5A PWM Buck DC/DC Converter
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 Sep. 29, 2004
1/5
Features
- Output voltage: 3.3V
- 300KHz +15% fixed switching frequency
- Voltage mode non-synchronous PWM control
- Thermal-shutdown and current-limit protection
- ON/OFF shutdown control input
- Operating voltage can be up to 22V
- Output load current: 2.5A
- SOP-7L packages
- Low power standby mode
- Built-in switching transistor on chip
Applications
- Simple High-efficiency step-down regulator
- On-card switching regulators
- Positive to negative converter
- DSL Modems
- Portable Computers
- Regulated Wall Adapters
- Distributed Power
General Description
The AP1503 series are monolithic ICs designed for
step-down DC/DC converters, and own the ability
of driving a 2.5A load without additional transistor
components. Due to reducing the number of
external component, the board space can be saved
easily. The external shutdown function can be
controlled by logic level and then come into standby
mode. The external compensation makes feedback
control have good line and load regulation.
Regarding protected function, thermal shutdown is
to prevent over temperature operating from damage,
and current limit is against over current operating of
the output switch. The AP1503 series operates at a
switching frequency of 300KHz thus allowing
smaller sized filter components than what would be
needed with lower frequency switching regulators.
Other features include a guaranteed +2% tolerance
on output voltage under specified input voltage and
output load conditions, and +15% on the oscillator
frequency. The output version included fixed 3.3V,
5V. The packages are available in a standard
SOP-7 lead package.
Pin Assignment
SOP7 with Heat Sink
VB
VIN
COMP
SD
FB
GND
VO
7
6
5
2
3
4
1
Pin Descriptions
Name
Description
V
IN
Operating
voltage
input
VB Boost
pin
SD ON/OFF
Shutdown
FB
Output voltage feedback control
COMP Compensation
pin
GND Ground
VO Switching
output
AP1503
300Khz, 2.5A PWM Buck DC/DC Converter
Anachip Corp.
www.anachip.com.tw Rev 1.0 Sep. 29, 2004
2/5
Ordering Information
Output version
Package
Packing
S : SOP-7L
AP1503 XX X
-33 : 3.3V
Blank : Tube
A : Taping
X X
Lead Free
Blank : Normal
L : Lead Free Package
Block Diagram
Current
Source
bias
1.235V
Reference
2.5V
Regulator
300kHz
OSC.
Start
up
+
+
_
+
_
Thermal
Shutdown
Pre-driver
Comp
Comp
GND
VO
VIN
SD
FB
220mV
200mV
3A
Switch
+
_
_
Amp
Comp
Frequecy
compen-
sation
COMP
VB
AP1503
300Khz, 2.5A PWM Buck DC/DC Converter
Anachip Corp.
www.anachip.com.tw Rev 1.0 Sep. 29, 2004
3/5
Absolute Maximum Ratings
Symbol
Parameter
Rating
Unit
V
CC
Supply
Voltage
+26
V
V
SD
ON/OFF Pin input voltage
-0.3 to +25
V
V
FB
Feedback Pin voltage
-0.3 to +25
V
V
OUT
Output voltage to Ground
-1
V
P
D
Power
dissipation
Internally limited
W
T
ST
Storage temperature
-65 to +150
o
C
T
OP
Operating temperature
-40 to +125
o
C
V
OP
Operating voltage
+7 to +40
V
Electrical Characteristics (All Output Voltage Versions)
Unless otherwise specified, V
IN
=12V for 3.3V, 5V, I
LOAD
= 0.5A
Symbol
Parameter
Conditions
Min.
Typ.
Max.
Unit
255 300 345
F
OSC
Oscillator
frequency
230 360
KHz
0.5
V
SAT
Saturation
voltage
I
SW
=2A
V
B
=V
IN
+2.5V.
0.4
0.6
V
Max. Duty Cycle (ON)
V
FB
=0V force driver on
90
DC
Min. Duty cycle (OFF)
V
FB
=6V force driver off
0
%
3.5
I
CL
Current
limit
Peak current
No outside circuit
V
FB
=0 force driver on
3 3.25
4
A
Output = 0
no outside circuit
V
FB
=6V force driver off
-1
uA
I
L
Output = -1
Output
leakage
current
V
IN
=24V
-1
mA
COMP Min SW threshold Duty Cycle=0%,F
B
=3.5V
0.04
V
C
2A I
SW
threshold
0.8
V
V
B
Min
V
B
above switch
I
SW
=2A
2.6
3
V
I
SW
=1A
120
I
B
Boost
current
I
SW
=2A
130
140
mA
I
Q
Quiescent
Current
V
FB
=6 force driver off
5
10
mA
150
I
STBY
Standby Quiescent
Current
ON/OFF pin=5V
V
IN
=24V
80
200
uA
V
IL
Low (regulator ON)
-
0.6
V
IH
ON/OFF pin logic input
threshold voltage
High (regulator OFF)
2.0
1.3
-
V
I
H
ON/OFF pin logic input
current
V
LOGIC
=2.5V (OFF)
-0.1
I
L
ON/OFF pin input current V
LOGIC
=0.5V (ON)
-1
uA
JC
Thermal Resistance
SOP-7L Junction to case
20
o
C/W
JA
Thermal Resistance
With copper area of
approximately 0.5 in
2
SOP-7L
Junction to
ambient
50
o
C/W
AP1503
300Khz, 2.5A PWM Buck DC/DC Converter
Anachip Corp.
www.anachip.com.tw Rev 1.0 Sep. 29, 2004
4/5
Electrical Characteristics (Continued)
Symbol
Parameter
Conditions
Typ.
Limit
Unit
OUT
V
Output voltage
7V < V
IN
< 24V
0.2A < I
LOAD
< 2.5A
3.3
3.23/3.2
3.37/3.4
V
V
MIN
V
MAX
AP1503-3.3V
Efficiency V
IN
= 12V, I
LOAD
=2A
79
%
Specifications with boldface type are for full operating temperature range, the other type are for T
J
=25C.
Typical Application Circuit
1
7
6
3
4
7V
DC Input
C
in
Capacitor
FB
SD
D1
Schottky Diode
Vin
GND
VO
AP1503
-33
Co
Capacitor
Inductor
L1
3.3V/2.5A
Output Load
2
VB
D2
Schottky Diode
COMP
5
CC
CB
AP1503
300Khz, 2.5A PWM Buck DC/DC Converter
Anachip Corp.
www.anachip.com.tw Rev 1.0 Sep. 29, 2004
5/5
Marking Information
( Top View )
Logo
Output Type
33 : 3.3V
ID code: internal
Year: "01" = 2001
"02" = 2002
Xth week: 01~52
~
1
4
AP1503 XX
YY WW X X
5
7
Blank: normal
L: Lead Free Package
Package Information
Package Type: SOP-7L
A
C
C2
B1
D
e
E
B2
F
C3
C1
Dimensions In Millimeters
Dimensions In Inches
Symbol
Min.
Nom.
Max.
Min.
Nom.
Max.
A 5.79 5.99 6.19
0.228
0.236
0.244
B1 3.83 3.91 3.99 0.151
0.154
0.157
B2 3.78 3.86 3.94 0.149
0.152
0.155
C 4.80 4.87 4.94 0.189
0.192
0.194
C1 1.57 1.67 1.77 0.062 0.066 0.070
C2 0.32 0.4 0.48 0.013 0.016 0.019
C3 1.17 1.27 1.37 0.046 0.050 0.054
D 0.19 0.22 0.25 0.007
0.009
0.010
E 1.04REF
0.041REF
e 0.48 0.68 0.88
0.019
0.027
0.035
F 1.35 1.45 1.55
0.053
0.057
0.061
7
o
7
o
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