AP1518
300KHz, 3A PWM Buck DC/DC Converter
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
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.
Applications
-
Simple High-efficiency step-down regulator
-
On-card switching regulators
-
Positive to negative converter
Pin Assignments
( Top View )
5 SD
4 FB
3 Gnd
2 Output
1 V
IN
Pin Descriptions
Name
V
IN
Output
GND
FB
SD
Description
Operating voltage input
Switching output
Ground
Output voltage feedback control
ON
/OFF Shutdown
Metal Tab GND
TO263-5L
( Top View )
5 SD
4 FB
3 Gnd
2 Output
1 V
IN
TO220-5L
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
AP1518
300KHz, 3A PWM Buck DC/DC Converter
Absolute Maximum Ratings
Symbol
V
CC
V
SD
V
FB
V
OUT
P
D
T
ST
T
OP
V
OP
Parameter
Supply Voltage
ON
/OFF Pin input voltage
Feedback Pin voltage
Output voltage to Ground
Power dissipation
Storage temperature
Operating temperature
Operating voltage
Rating
+24
-0.3 to +18
-0.3 to +18
-1
Internally limited
-65 to +150
-40 to +125
+4.5 to +22
Unit
V
V
V
V
W
o
C
o
C
V
Electrical Characteristics (All Output Voltage Versions)
Unless otherwise specified, V
IN
=12V, I
LOAD
= 0.5A
Symbol
I
FB
F
OSC
F
SCP
V
SAT
DC
I
CL
I
L
I
Q
I
STBY
V
IL
V
IH
I
H
I
L
Θ
JC
Θ
JA
Parameter
Feedback bias current
Oscillator frequency
Conditions
V
FB
=0.8V
(Adjustable version only)
Min.
255
220
10
Typ.
-10
300
30
1.4
100
0
Max.
-50
-100
345
345
50
1.6
1.7
Unit
nA
KHz
KHz
V
%
of When current limit occurred
o
and V
FB
< 0.5V, Ta=25 C
I
OUT
=3A
Saturation Voltage
No outside circuit
V
FB
=0V force driver on
Max. Duty Cycle (ON)
V
FB
=0V force driver on
Min. Duty Cycle (OFF)
V
FB
=12V force driver off
Peak current
Current limit
No outside circuit
V
FB
=0 force driver on
Output No outside circuit
Output = 0V
leakage V
FB
=12 force driver off
current V
IN
=22V
Output =-1V
Quiescent Current
V
FB
=12 force driver off
Standby Quiescent
ON
/OFF pin=5V
Current
V
IN
=22V
Low (regulator ON)
ON
/OFF pin logic input
High (regulator OFF)
threshold voltage
ON
/OFF pin logic
input current
ON
/OFF pin input
current
Oscillator frequency
short circuit protect
5.5
3.6
4.5
6.5
-200
-5
5
70
-
2.0
1.3
10
150
200
0.6
-
-0.01
uA
-0.1
2.5
3.5
28
23
-1
o
A
uA
mA
mA
uA
V
V
LOGIC
=2.5V (OFF)
V
LOGIC
=0.5V (ON)
TO220-5L
TO263-5L
TO220-5L
TO263-5L
Junction to
case
Junction to
ambient
Thermal Resistance
Thermal Resistance
With copper area of
approximately 3 in
2
C/W
C/W
o
Specifications with
boldface type
are for full operating temperature range, the other type are for T
J
=25ºC.
Anachip Corp.
www.anachip.com.tw
3/12
Rev.1.1 Oct 29, 2004
AP1518
300KHz, 3A PWM Buck DC/DC Converter
Typical Performance Characteristics
AP1518 Efficiency v.s. Temperature
(Vin=12V,Vout=5V,Io=3A)
83
82
81
80
79
78
77
76
75
74
73
72
-50 -30 -10 10
30
50
70
90 110 130 150
AP1518 Efficiency v.s. Temperature
(Vin=12V,Vout=3.3V,Io=3A)
78
77
76
Efficiency (%)
Efficiency (%)
75
74
73
72
71
70
-50 -30 -10 10
30
50
70
90 110 130 150
Temperature (TA) (°C)
Temperature (TA) (°C)
AP1518 Saturation Voltage v.s. Temperature
(Vcc=12V,Vfb=0V,VSD=0)
1.6
1.5
AP1518 Switch Current Limit v.s. Temperature
(Vcc=12V,Vfb=0V)
5.5
Saturation Voltage (V)
1.4
1.3
1.2
1.1
1
0.9
0.8
0.7
-50
-25
0
25
1A
0.5A
3A
2A
Switch Current Limit (A)
5
4.5
4
3.5
3
-50
-30
-10
10
30
50
70
90
50
75
100
125
Temperature (TA) (°C)
Temperature (TA) (°C)
AP1518 Supply Current v.s. Temperature
(Vcc=12V , No Load ,Von/off =0V(Switch ON) ,Von/off =5V(Switch OFF))
15
14
13
12
11
10
9
8
7
6
5
60
Supply Current (mA)
Supply Current (uA)
55
50
45
40
35
30
-50 -30 -10 10
30
50
70
90 110 130 150
Switch OFF
Switch ON
-50 -30 -10 10
30
50
70
90 110 130 150
Temperature (TA) (°C)
Temperature (TA) (°C)
Anachip Corp.
www.anachip.com.tw
5/12
Rev.1.1 Oct 29, 2004
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