AP1534
PWM CONTROL 2A STEP-DOWN CONVERTER
AP1534 Rev. 2 1 of 8 DECEMBER 2007
www.diodes.com© Diodes Incorporated
• Input voltage: 4.4V to 18V
• Output voltage: 0.8V to VCC.
• Duty ratio: 0% to 99% PWM control
• Oscillation frequency: 300KHz typ.
• Current limit, Enable function
• Thermal Shutdown function
• Built-in internal SW P-channel MOS
• SOP-8L: Available in “Green” Molding Compound
(no Br, Sb)
• Lead Free Finish/RoHS Compliant (Note 1)
AP1534 consists of step-down switching regulator with PWM
control. These devices include a reference voltage source,
oscillation circuit, error amplifier, internal PMOS.
AP1534 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 99%. 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 300KHz to 50KHz. Also, an internal
compensation block is built in to minimize external component
count.
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-packages, 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.
• PC Motherboard
• LCD Monitor
• Graphic Card
• DVD-Video Player
• Telecom Equipment
• ADSL Modem
• Printer and other Peripheral Equipment
• Microprocessor Core Supply
A P 1 5 3 4 X X X
Package Packing
S : SOP-8L
Lead Free
-U : Tube
-13 : Tape & Reel
G : Green
Note: 1. RoHS revision 13.2.2003. Glass and High Temperature Solder Exemptions Applied, see EU Directive Annex Notes 5 and 7.
Tube 13” Tape and Reel
Device Package
Code
Packaging
(Note 2) Quantity Part Number
Suffix
Quantity Part Number
Suffix
AP1534S S SOP-8L 100 -U 2500/Tape & Reel -13
Note: 2. Pad layout as shown on Diodes Inc. suggested pad layout document AP02001, which can be found on our website at
https://www.diodes.com/datasheets/ap02001.pdf.
Features General Description
Applications
Ordering Information
AP1534
PWM CONTROL 2A STEP-DOWN CONVERTER
AP1534 Rev. 2 2 of 8 DECEMBER 2007
www.diodes.com© Diodes Incorporated
Pin Assignments
1
2
3
4
8
7
6
5
FB
OCSET Output
Output
EN
Vss
Vss
VCC
SOP-8L
AP1534
Pin Descriptions
Pin Name Pin No. Description
FB 1 Feedback pin
EN 2
Power-off pin
H: Normal operation
(Step-down operation)
L: Step-down operation stopped
(All circuits deactivated)
OCSET 3 Add an external resistor to set max output current
VCC 4 IC power supply pin
Output 5, 6 Switch Pin. Connect external inductor/diode here. Minimize
trace area at this pin to reduce EMI
VSS 7, 8 GND Pin
AP1534
PWM CONTROL 2A STEP-DOWN CONVERTER
AP1534 Rev. 2 3 of 8 DECEMBER 2007
www.diodes.com© Diodes Incorporated
Block Diagram
Oscillation
Circuit
Reference Voltage
Source
PWM-Switched
Control Circuit
+
-
V Vss EN
EN
100uA
OCSET
FB
Vcc
Thermal
Shutdown
Output
Absolute Maximum Ratings
Symbol Parameter Rating Unit
ESD HBM Human Body Model ESD Protection 4.5 KV
ESD MM Machine Model ESD Protection 150 V
VCC VCC Pin Voltage VSS - 0.3 to VSS + 20 V
VFB Feedback Pin Voltage VSS - 0.3 to VCC V
VEN EN Pin Voltage VSS - 0.3 to VIN V
VOUT Switch Pin Voltage VSS - 0.3 to VIN V
PD Power Dissipation Internally limited mW
TJ Operating Junction Temperature Range -20 to +125 oC
TST Storage Temperature Range -40 to +150 oC
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.
Recommended Operating Conditions
Symbol Parameter Min Max Unit
VIN Input Voltage 4.4 18 V
IOUT Output Current 0 2 A
TA Operating Ambient Temperature -25 85 oC
AP1534
PWM CONTROL 2A STEP-DOWN CONVERTER
AP1534 Rev. 2 4 of 8 DECEMBER 2007
www.diodes.com© Diodes Incorporated
Electrical Characteristics ( VIN = 12V, TA = 25°C, unless otherwise specified )
Symbol Parameter Conditions Min Typ. Max Unit
VFB Feedback Voltage IOUT = 0.1A 0.784 0.8 0.816 V
IFB Feedback Bias Current IOUT = 0.1A - 0.1 0.5 μA
ISW Switch Current -- 2.0 - - A
ISHDN Current Consumption
During Power Off VEN = 0V - 10 - μA
ΔVOUT
/ VIN Line Regulation VIN = 5V~18V - 1 2 %
ΔVOUT
/VOUT Load Regulation IOUT = 0.1 to 2A - 0.2 0.5 %
fOSC Oscillation Frequency Measure waveform at SW pin00 KHz
fOSC1 Frequency of Current Limit
or Short Circuit Protect Measure waveform at SW pin - 50 - KHz
VIH Evaluate oscillation at SW pin 2.0 - -
VIL EN Pin Input Voltage Evaluate oscillation stop at SW pin - - 0.8 V
ISH -- - 20 - μA
ISL
EN Pin Input Leakage
Current -- - -10 - μA
IOCSET OCSET Pin Bias Current μA
RDS(ON) Internal MOSFET RDS(ON) VVIINN == 152VV, V, VFBF B= = 0 V0V -- 116000 -- mΩ
EFFI Efficiency VIN = 12V, VOUT = 5V
IOUT = 2A - 91 - %
TSHDN Thermal shutdown threshold - 150 - °C
THYS Thermal shutdown
hysteresis - 55 - °C
θJA Thermal Resistance
Junction-to-Ambient SOP-8L (Note 3) - 127 - oC/W
θJC Thermal Resistance
Junction-to-Case SOP-8L (Note 3) - 28 - oC/W
Note: 3. Test condition for SOP-8L: Device mounted on FR-4 substrate PC board, 2oz copper, with minimum recommended pad layout.
For better thermal performance, larger copper pad for heatsink is needed.
Typical Application Circuit
AP1534
+
V - EN SS
CC
RA
B240A RB
FB
Vcc Output
CVcc
VOUT =5V/2A
VIN
ROCSET
OCSET COUT CIN
Optional
COCSET
CEN
REN
Option
100K
Note: VOUT = VFB x (1+RA /RB)
RB =0.7K~5K ohm
L1
22uH
6.8K
1.3K
5.6K
0.1uF
+
-
C
470uF 0.1uF 470uF
0.1uF (Note 4)
D1
Note: 4. Suggested DIODES Power Schottky P/N: B240/B340 series.
AP1534
PWM CONTROL 2A STEP-DOWN CONVERTER
AP1534 Rev. 2 5 of 8 DECEMBER 2007
www.diodes.com© Diodes Incorporated
Typical Performance Characteristics
VIN vs Frequency
(VOUT=3.3V, IOUT=0.2A)
306
308
310
312
314
316
318
320
322
324
326
0 2 4 6 8 1 18
VIN (V)
FOSC (kHz)
VIN vs VFB
(VOUT=3.3V, IOUT=0.2A)
0.780
0.785
0.790
0.795
0.800
0.805
0.810
0.815
0.820
0 2 4 6 8 1 18
VIN (V)
VFB (V)
Line Regulation
(VOUT=3.3V, IOUT=0.2A)
-3.0%
-2.0%
-1.0%
0.0%
1.0%
2.0%
3.0%
0 2 4 6 8 1 18
VIN (V)
VOUT CHANGE (%)
Load Regulation
(VIN=5V, VOUT=3.3V)
-1.0%
-0.8%
-0.6%
-0.4%
-0.2%
0.0%
0.2%
0.4%
0.6%
0.8%
1.0%
0.0 0.5 IO1UT.0 (A) 1.5 2.0
VOUT CHANGE (%) Efficiency
0
10
20
30
40
50
60
70
80
90
100
0.0 0.5 1.0 1.5 2.0
IOUT (A)
Efficiency (%)
VOUT=3.3V
VOUT=5V
AP1534
PWM CONTROL 2A STEP-DOWN CONVERTER
AP1534 Rev. 2 6 of 8 DECEMBER 2007
www.diodes.com© Diodes Incorporated
Typical Performance Characteristics (Continued)
Vout Ripple
(Vin=5V, Vout=3.3V, Iout=0.1A)
Vout Ripple
(Vin=5V, Vout=3.3V, Iout=2A)
Test Circuit
A
VCC FB
VSS
EN
open
open
FB
EN
+
-
Oscillation
OUTPUT A OUTPUT
FB
EN
+
-
+
-
V
OUTPUT
OCSET
OCSET
OCSET
Enable function test Feedback function test
Operation function test
VCC
VCC
VSS
VSS
AP1534
PWM CONTROL 2A STEP-DOWN CONVERTER
AP1534 Rev. 2 7 of 8 DECEMBER 2007
www.diodes.com© Diodes Incorporated
Function Description
PWM Control
The AP1534 is a DC/DC converter that employs pulse width
modulation (PWM) scheme. Its pulse width varies in the range of
0% to 99%, based on the output current loading. The output
ripple voltage caused by the PWM high frequency switching can
easily be reduced through an output filter. Therefore, this
converter provides a low ripple output supply over a broad range
of input voltage & output current loading
Under Voltage Lockout
The under voltage lockout circuit of the AP1534 assures that the
high-side MOSFET driver remains in the off state whenever the
supply voltage drops below 3.3V. Normal operation resumes
once VCC rises above 3.5V.
Current Limit Protection
The current limit threshold is set by external resistor ROCSET
connected from VCC supply to OCSET pin. The internal sink
current IOCSET (90uA typical) across this resistor sets the voltage
at OCSET pin. When the PWM voltage is less than the voltage at
OCSET, an over-current condition is triggered.
The current limit threshold is given by the following equation:
IPEAK RDS(ON) IOCSET ROCSET
× = ×
2
( I)
IPEAK IOUT (MAX)
Δ
> +
where,
IN
OUT
S
IN OUT
V
V
x
F xL
V V
I
−
Δ =
IPEAK is the output peak current; RDS (ON) is the MOSFET ON
resistance; FS is the PWM frequency (300KHz typical). Also, the
inductor value will affect the ripple current ΔI.
The above equation is recommended for input voltage range of
5V to 18V. For input voltage lower than 5V, higher than 18V or
ambient temperature over 100°C, ROCSET≧6.8KΩ is
recommended.
The recommended minimum ROCSET value is summarized below:
VIN (V) VOUT (V) ROCSET (Ω)
4 1 6.8K
5 3.3 5.6K
12 5 3.9K
18 12 4.7K
The maximum ROCSET value should not exceed AP1533 maximum
current output.
( Top View )
SOP-8L
AP1534
YYWWX X
Logo
Part No.
Internal code
Year : "07" = 2007
"08" = 2008
Xth week: 01~52
~
8 5
1 4
G : Green
Marking Information
AP1534
PWM CONTROL 2A STEP-DOWN CONVERTER
AP1534 Rev. 2 8 of 8 DECEMBER 2007
www.diodes.com© Diodes Incorporated
Package Information (All Dimensions in mm)
1.27typ 0.3/0.5
7°~9°
4.80/5.30
3.70/4.10
5.79/6.20
0.20typ
7°~9°
3.70/4.10
0.38/1.27
0.08/0.25
Gauge Plane
0.254
Seating Plane
0.35max.45°
Detail "A"
Detail "A"
1.30/1.50
1.75max.
Land Pattern Recommendation
0.78
(Unit: mm)
6x-1.27
8x-1.55
8x-0.60
5.4
IMPORTANT NOTICE
LIFE SUPPORT
Diodes Incorporated and its subsidiaries reserve the right to make modifications, enhancements, improvements, corrections or other changes without further
notice to any product herein. Diodes Incorporated does not assume any liability arising out of the application or use of any product described herein; neither
does it convey any license under its patent rights, nor the rights of others. The user of products in such applications shall assume all risks of such use and will
agree to hold Diodes Incorporated and all the companies whose products are represented on our website, harmless against all damages.
Diodes Incorporated products are not authorized for use as critical components in life support devices or systems without the expressed written approval of the
President of Diodes Incorporated.

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