AP1518
300KHz, 3A 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.1.1 Oct 29, 2004
1/12
Features
- Adjustable version output voltage range, 0.8V to
18V+4%
- 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: 3A
- TO220-5L and TO263-5L Pb-Free 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
General Description
The AP1518 series are monolithic IC designed for a
step-down DC/DC converter, and own the ability of
driving a 3A load without external transistor. 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 internal
compensation makes feedback control have good
line and load regulation without external design.
Regarding protected function, thermal shutdown is
to prevent over temperature operating from damage,
and current limit is to prevent over current operating
of the output switch. If current limit function
occurred and V
FB
is down to 0.5V below, the
switching frequency will be reduced. The AP1518
series operate 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 +4% tolerance on output voltage under
specified input voltage and output load conditions,
and +15% on the oscillator frequency. The
packages are available in a standard 5-lead
TO-220 package or a 5-lead TO-263.
Pin Assignments
TO220-5L
( Top View )
( Top View )
TO263-5L
1 V
IN
5 SD
4 FB
3 Gnd
2 Output
Metal Tab GND
1 V
IN
5 SD
4 FB
3 Gnd
2 Output
Pin Descriptions
Name
Description
V
IN
Operating
voltage
input
Output Switching
output
GND Ground
FB
Output voltage feedback control
SD
ON
/OFF Shutdown
AP1518
300KHz, 3A PWM Buck DC/DC Converter
Anachip Corp.
www.anachip.com.tw Rev.1.1 Oct 29, 2004
2/12
Ordering Information
Package
T5: TO220-5L
K5: TO263-5L
AP1518 X X
Packing
Blank : Tube
A : Taping
T5R: TO220-5L(R)
Block Diagram
Current
Source
bias
0.8V
Reference
2.5V
Regulator
300kHz
OSC.
Start
up
+
+
_
+
_
Thermal
Shutdown
Pre-driver
Comp
Comp
Gnd
Output
V
IN
SD
FB
220mV
200mV
3A
Switch
+
_
_
Amp
Comp
Frequecy
compen-
sation
AP1518
300KHz, 3A PWM Buck DC/DC Converter
Anachip Corp.
www.anachip.com.tw Rev.1.1 Oct 29, 2004
3/12
Absolute Maximum Ratings
Symbol
Parameter
Rating
Unit
V
CC
Supply
Voltage
+24
V
V
SD
ON /OFF Pin input voltage
-0.3 to +18
V
V
FB
Feedback Pin voltage
-0.3 to +18
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
+4.5 to +22
V
Electrical Characteristics (All Output Voltage Versions)
Unless otherwise specified, V
IN
=12V, I
LOAD
= 0.5A
Symbol
Parameter
Conditions
Min.
Typ.
Max.
Unit
-50
I
FB
Feedback bias current
V
FB
=0.8V
(Adjustable version only)
-10
-100
nA
255 300 345
F
OSC
Oscillator
frequency
220 345
KHz
F
SCP
Oscillator frequency of
short circuit protect
When current limit occurred
and V
FB
< 0.5V, Ta=25
o
C
10 30 50 KHz
1.6
V
SAT
Saturation
Voltage
I
OUT
=3A
No outside circuit
V
FB
=0V force driver on
1.4
1.7
V
Max. Duty Cycle (ON)
V
FB
=0V force driver on
100
DC
Min. Duty Cycle (OFF)
V
FB
=12V force driver off
0
%
5.5
I
CL
Current
limit
Peak current
No outside circuit
V
FB
=0 force driver on
3.6 4.5
6.5
A
Output = 0V
No outside circuit
V
FB
=12 force driver off
-200
uA
I
L
Output =-1V
Output
leakage
current V
IN
=22V
-5
mA
I
Q
Quiescent
Current
V
FB
=12 force driver off
5
10
mA
150
I
STBY
Standby Quiescent
Current
ON
/OFF pin=5V
V
IN
=22V
70
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)
-0.01
I
L
ON
/OFF pin input
current
V
LOGIC
=0.5V (ON)
-0.1
-1
uA
TO220-5L
2.5
JC
Thermal Resistance
TO263-5L
Junction to
case
3.5
o
C/W
TO220-5L
28
JA
Thermal Resistance
With copper area of
approximately 3 in
2
TO263-5L
Junction to
ambient
23
o
C/W
Specifications with boldface type are for full operating temperature range, the other type are for T
J
=25C.
AP1518
300KHz, 3A PWM Buck DC/DC Converter
Anachip Corp.
www.anachip.com.tw Rev.1.1 Oct 29, 2004
4/12
Electrical Characteristics (Continued)
Sym.
Parameter
Conditions
Typ.
Limit
Unit
FB
V
Output
Feedback
5V < V
IN
< 22V
0.2A < I
LOAD
< 3A
0.8
0.784/0.768
0.816/0.832
V
V
MIN
V
MAX
Efficiency
V
OUT
programmed for 3V
V
IN
= 12V, I
LOAD
=3A
74
%
Efficiency
V
OUT
programmed for 3.3V
V
IN
= 12V, I
LOAD
=3A
75
%
Efficiency
V
OUT
programmed for 5V
V
IN
= 12V, I
LOAD
=3A
80
%
AP1518
Efficiency
V
OUT
programmed for 12V
V
IN
= 16V, I
LOAD
= 3A
89
%
Specifications with boldface type are for full operating temperature range, the other type are for T
J
=25C.
AP1518
300KHz, 3A PWM Buck DC/DC Converter
Anachip Corp.
www.anachip.com.tw Rev.1.1 Oct 29, 2004
5/12
Typical Performance Characteristics
AP1518 Efficiency v.s. Temperature
(Vin=12V,Vout=5V,Io=3A)
72
73
74
75
76
77
78
79
80
81
82
83
-50 -30 -10 10 30 50 70 90 110 130 150
Temperature (TA) (C)
Efficie
n
c
y (%)
AP1518 Efficiency v.s. Temperature
(Vin=12V,Vout=3.3V,Io=3A)
70
71
72
73
74
75
76
77
78
-50 -30 -10 10 30 50 70 90 110 130 150
Temperature (TA) (C)
Efficie
n
cy (%)
AP1518 Saturation Voltage v.s. Temperature
(Vcc=12V,Vfb=0V,VSD=0)
0.7
0.8
0.9
1
1.1
1.2
1.3
1.4
1.5
1.6
-50
-25
0
25
50
75
100
125
Temperature (TA)(C)
S
a
turati
on V
o
l
t
age (V
)
3A
2A
1A
0.5A
AP1518 Switch Current Limit v.s. Temperature
(Vcc=12V,Vfb=0V)
3
3.5
4
4.5
5
5.5
-50
-30
-10
10
30
50
70
90
Temperature (TA) (C)
Swi
t
ch Current Li
mi
t (A)
AP1518 Supply Current v.s. Temperature
(Vcc=12V , No Load ,Von/off =0V(Switch ON) ,Von/off =5V(Switch OFF))
5
6
7
8
9
10
11
12
13
14
15
-50 -30 -10 10
30
50
70
90 110 130 150
Temperature (TA) (C)
Supply
Current (m
A)
Switch ON
30
35
40
45
50
55
60
-50 -30 -10 10
30
50
70
90 110 130 150
Temperature (TA) (C)
Supply
Current (uA)
Switch OFF
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