ANACHIP AP1537S

AP1537
PWM Control 3A Step-Down Converter
„ Features
„ General Description
- Input voltage: 3.6V to 18V.
- Output voltage: 0.8V to VCC.
- Duty ratio: 0% to 100% PWM control
- Oscillation frequency: 500KHz typ.
- Soft-start, Current Limit, Enable function
- Thermal Shutdown function
- Built-in internal SW P-channel MOS
- Low ESR output capacitor (Multi-layer chip
capacitor (MLCC)) application
- SOP-8L Pb-Free Package.
AP1537 consists of step-down switching regulator
with PWM control. These devices include a reference
voltage source, oscillation circuit, error amplifier,
internal PMOS and etc.
AP1537 provides low-ripple power, high efficiency,
and excellent transient characteristics. The PWM
control circuit is able to vary the duty ratio linearly
from 0 up to 100%. This converter also contains an
error amplifier circuit as well as a soft-start circuit that
prevents overshoot at startup. An enable function,
an over current protect function and a short circuit
protect function are built inside, and when OCP or
SCP happens, the operation frequency will be
reduced from 500KHz to 50KHz. Also, an internal
compensation block is built in to minimum external
component count.
„ Applications
- PC Motherboard
- LCD Monitor
- Graphic Card
- DVD-Video Player
- Telecom Equipment
- ADSL Modem
- Printer and other Peripheral Equipment
- Microprocessor core supply
- Networking power supply
With the addition of an internal P-channel Power MOS,
a coil, capacitors, and a diode connected externally,
these ICs can function as step-down switching
regulators. They serve as ideal power supply units for
portable devices when coupled with the SOP–8L
mini-package, providing such outstanding features as
low current consumption. Since this converter can
accommodate an input voltage up to 18V, it is also
suitable for the operation via an AC adapter.
„ Pin Assignments
„ Pin Descriptions
)
8
Vss
7
Vss
Comp 3
6
Output
VCC 4
5
Output
FB 1
EN 2
Name
FB
EN
AP1537
Comp
VCC
Output
VSS
Pin
1
Description
Feedback pin
Power-off pin
H: Normal operation
(Step-down operation)
2
L: Step-down operation stopped
(All circuits deactivated)
3
Compensation pin
4
IC power supply pin
Switch Pin. Connect external
5、6 inductor/diode here. Minimize trace
area at this pin to reduce EMI.
7、8 GND Pin
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. 3
1/7
May 09, 2006
AP1537
PWM Control 3A Step-Down Converter
„ Ordering Information
AP 1537 X X
Packing
Blank : Tube
A : Taping
Package
S: SOP-8L
„ Block Diagram
Output
Oscillation
Circuit
Reference Voltage
Source with Soft Start
Vcc
+
PWM-Switched
Control Circuit
FB
-
Thermal
Shutdown
100uA
VEN
EN
Vss
Comp
„ Absolute Maximum Ratings
Symbol
VCC*1
VFB
VEN
VOUTPUT
PD
TOPR
TSTG
θJC
θJA
Parameter
VCC Pin Voltage
Feedback Pin Voltage
EN Pin Voltage
Switch Pin Voltage
Power Dissipation
Junction Operating Temperature Range
Storage Temperature Range
Thermal Resistance Junction-to-Case
3 inch2 Copper as a heat-sink
Thermal Resistance Junction-to-Case
3 inch2 Copper as a heat-sink
Rating
VSS - 0.3 to VSS + 20
VSS - 0.3 to VCC
VSS - 0.3 to VIN + 0.3
VSS - 0.3 to VIN + 0.3
1000
-20 to +125
-40 to +150
Unit
V
V
V
V
mW
o
C
o
C
15
o
C/W
65
o
C/W
Caution: The absolute maximum ratings are rated values exceeding which the product could suffer physical damage. These values must
therefore not be exceeded under any conditions.
Anachip Corp.
www.anachip.com.tw
Rev. 1.3
2/7
May 09, 2006
AP1537
PWM Control 3A Step-Down Converter
„ Electrical Characteristics (VIN = 12V, Ta=25°C, unless otherwise specified)
Symbol
VIN
VFB
IFB
ISW
ISSS
Parameter
Input Voltage
Feedback Voltage
Feedback Bias Current
Switch Current
Current Consumption
During Power Off
Conditions
∆VOUT
Line Regulation
/VOUT
∆VOUT
Load Regulation
/VOUT
fOSC Oscillation Frequency
Frequency of Current Limit
fOSC1
or Short Circuit Protect
VSH
EN Pin Input Voltage
VSL
ISH
EN Pin Input Leakage
Current
ISL
TSS
Soft-Start Time
RDSON Internal MOSFET Rdson
EFFI
Min.
3.6
0.784
3.5
Typ.
0.8
0.1
-
Max.
18
0.816
0.5
-
Unit
V
V
µA
A
VEN =0V
-
10
-
µA
VIN = 5V~18V, IOUT=0.2A
-
1
2
%
IOUT = 0.1 to 3A
-
0.2
0.5
%
Measure waveform at SW pin
400
500
600
KHz
Measure waveform at SW pin
40
-
-
KHz
Evaluate oscillation at SW pin
Evaluate oscillation stop at SW pin
VIN = 12V
--VIN=5V, VFB=0V
VIN=12V, VFB=0V
VIN = 12V, VOUT = 5V
IOUT = 3A
2.0
-10
-10
0.3
-
2
110
70
0.8
10
10
5
150
100
-
91
-
-IOUT=0.1A
IOUT=0.1A
--
Efficiency
V
µA
µA
ms
mΩ
%
„ Typical Application Circuit
Vcc
VIN
REN
100K
CIN
22uF
0.1uF
22uH
CC
10nF
AP1537
FB
EN
VSS
CVcc
L1
Output
VOUT =5V
RA
6.8K
+
Comp
1K
CEN
0.1uF
D1
1800pF
-
+
C
0.1uF
-
COUT
33uF
RB
1.3K
Note: V OUT = VFB x (1+R A/RB)
R B=0.7K~5K ohm
VOUT
L1 Value
VIN=12V, IMAX=3A
2.5V
3.3V
18uH
22uH
Anachip Corp.
www.anachip.com.tw
5V
22uH
Rev. 1.3
3/7
May 09, 2006
AP1537
PWM Control 3A Step-Down Converter
AP1537 Vin v.s. Frequency
(Vout=3.3V; Iout=0.2A)
450
445
440
435
430
425
420
415
410
405
400
FB (V)
Fosc (KHz)
„ Typical Performance Characteristics
0
5
10
15
Vin (V)
0
3.35
Vout (A)
Vout(V)
3.30
3.25
3.20
3.15
3.10
0
5
10
15
Vin(V)
0.84
0.83
0.82
0.81
0.80
0.79
0.78
0.77
0.76
0.75
0.74
20
AP1537 Line Regulation
( Iout=0.2A)
3.40
20
AP1537 Vin v.s. FB
(Vout=3.3V; Iout=0.2A)
5
10
15
Vin (V)
20
AP1537 Load Regulation
(Vin=12V)
5.10
5.09
5.08
5.07
5.06
5.05
5.04
5.03
5.02
5.01
5.00
0.0
1.0
2.0
3.0
Rev. 1.3
May 09, 2006
Iout (A)
AP1537 Efficiency
Efficiency (%)
100
90
80
70
60
50
40
30
20
Vout:5.0V
Vout:3.3V
10
0
0.0
1.0
Iout (A)
2.0
3.0
Anachip Corp.
www.anachip.com.tw
4/7
AP1537
PWM Control 3A Step-Down Converter
„ Typical Performance Characteristics (Continued)
AP1537 Vout Ripple
(Vin=12V; Vout=5V; Iout=0.2A)
AP1537 Vout Ripple
(Vin=12V; Vout=5V; Iout=3A)
„ Test Circuit
VCC
OUTPUT
FB
Comp
EN
A
Oscillation
open
open
A
open
-
VSS
OUTPUT
OUTPUT
FB
Comp
+
Enable function test
VCC
VCC
EN
VSS
Feedback function test
FB
+
EN
-
VSS
Comp
+
V
-
Operation function test
Anachip Corp.
www.anachip.com.tw
Rev. 1.3
5/7
May 09, 2006
AP1537
PWM Control 3A Step-Down Converter
„ Function Description
PWM Control
The AP1537 consists of DC/DC converters that
employ a pulse-width modulation (PWM) system.
In converters of the AP1537, the pulse width varies
in a range from 0 to 100%, according to the load
current. The ripple voltage produced by the
switching can easily be removed through a filter
because the switching frequency remains constant.
Therefore, these converters provide a low-ripple
power over broad ranges of input voltage and load
current.
Under Voltage Lockout
The under voltage lockout circuit of the AP1537
assures that the high-side MOSFET driver outputs
remain in the off state whenever the supply voltage
drops below 3.3V. Normal operation resumes once
VCC rises above 3.5V.
RDS(ON) Current Limiting
The current limit threshold is setting by the internal
circuit.
„ Marking Information
( Top View )
8
5
Logo
AP1537
Part no.
YY WW X
4
Anachip Corp.
www.anachip.com.tw
~
1
ID code: internal
Xth week: 01~52
Year: "01" =2001
"02" =2002
Rev. 1.3
6/7
May 09, 2006
AP1537
PWM Control 3A Step-Down Converter
„ Package Information
H
E
Package Type: SOP-8L
L
VIEW "A"
D
0.015x45
7 (4X)
e
B
A1
C
A
A2
7 (4X)
VIEW "A"
y
Symbol
A
A1
A2
B
C
D
E
e
H
L
y
θ
Dimensions In Millimeters
Min.
Nom.
Max.
1.40
1.60
1.75
0.10
0.25
1.30
1.45
1.50
0.33
0.41
0.51
0.19
0.20
0.25
4.80
5.05
5.30
3.70
3.90
4.10
1.27
5.79
5.99
6.20
0.38
0.71
1.27
0.10
8O
0O
Anachip Corp.
www.anachip.com.tw
Dimensions In Inches
Min.
Nom.
Max.
0.055
0.063
0.069
0.040
0.100
0.051
0.057
0.059
0.013
0.016
0.020
0.0075
0.008
0.010
0.189
0.199
0.209
0.146
0.154
0.161
0.050
0.228
0.236
0.244
0.015
0.028
0.050
0.004
0O
8O
Rev. 1.3
7/7
May 09, 2006