AP5004
PWM CONTROL 2.5A STEP-DOWN CONVERTER
AP5004
Document number: DS31444 Rev. 5 - 2 1 of 11
www.diodes.com August 2010
© Diodes Incorporated
Description
The AP5004 is a step-down switching regulator with PWM
control and includes a reference voltage source, oscillation
circuit, error amplifier, and an internal NMOS.
AP5004 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 90%. An
enable function, an over-current protect function, and a short
circuit protect function are built insid e, and when OCP or SCP
happens, the operation frequency will be reduced from
300 KHz to 50 KHz. Also, an internal compensation block has
been designed in to minimize the external component count.
With built-in power NMOS, a step-down switching regulator
can easily be built by adding a coil, capacitors, and a diode.
The combination of high efficiency, low standby current, high
input voltage (32V), and high output current (2.5A)in a small
SOP-8L package gives the AP5004 an unprecedented
advantage in any high power system applications.
Features
• Input Voltage: 10V to 32V
• Adjustable Output Voltage from 0.8V to 6V
• Duty Ratio: 0% to 90% PWM control
• Oscillation Frequency: 300KHz typical
• Short Circuit Protect Frequency:50 KHz
• 2uA Maximum Standby Curre nt
• Current Limit, Enable Function
• Thermal Shutdown Function
• Built-in Internal SW N-channel MOS
• SOP-8L: Available in “Green” Molding Compound
(No Br, Sb)
• Lead Free Finish/ RoHS Compliant (Note 1)
Pin Assignments
AP5004
1
2
37
6
54
8
(Top View )
GND
GND
Vcc
Vcc
EN
FB
Vboost
Output
SOP-8L
Applications
• Microprocessor Core Supply
• Networking Power Supply
• LCD MNT, TV Power Supply
• Telecom Power Supply
Notes: 1. EU Directive 2002/95/EC (RoHS). All applicable RoHS exemptions applied. Please visit our website at
http://www.diodes.com/products/lead_free.html.
AP5004
PWM CONTROL 2.5A STEP-DOWN CONVERTER
AP5004
Document number: DS31444 Rev. 5 - 2 2 of 11
www.diodes.com August 2010
© Diodes Incorporated
Typical Application Circuit
Vboost
GND
VCC
AP5004
GND
VCC
Output
FB
EN
5
6
VIN
C3
0.1uF
1
C2
220uF/63V
8
34
2
7
D1
B340
R1
685ohm
L1-(WURTH 744132)
33uH
C5
0.1uF
C1
100pF
VOUT = 5V
R5
100K
C6
0.1uF
U1
C7 0.1uF
12
R2
130ohm
C4
470uF/16V
Note: V OUT = VFB x (1+R1/R2)
R B= 100 ~ 300 ohm
Notes: 2. Suggested DIODES Power Schottky P/N: PDS540 or B540C.
Pin Descriptions
Pin Name Pin # Description
EN 1
H: Normal operation
L: St ep-down operation stopped
FB 2 Feedback pin
Vboost 3 High-side gate driver boost pin
Output 4 Switch output pin
VCC 5、6 VCC
GND 7、8 GND pin
AP5004
PWM CONTROL 2.5A STEP-DOWN CONVERTER
AP5004
Document number: DS31444 Rev. 5 - 2 3 of 11
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© Diodes Incorporated
Functional Block Diagram
Oscillation
Circuit Reference Volt age
PWM -Switched
Control Circuit +
-
GNDEN
Output
FB
Vboost
Vcc
VEN
Driver
Thermal
Shutdown
VL
Absolute Maximum Ratings
Symbol Parameter Rating Unit
ESD HBM Human Body Model ESD Protection 1.8 KV
ESD MM Machine Model ESD Protection 550 V
VCC VCC Pin Voltage VSS - 0.3 to VSS + 35 V
VFB VOUT Pin Voltage VSS - 0.3 to VCC V
VEN EN Pin Voltage VSS - 0.3 to VCC + 0.3 V
Vboost V
boost Pin Voltage VOUTPUT + 7V V
VOUTPUT Switch Pin Voltage VSS - 0.3 to VCC + 0.3 V
TJ Operating Junction Temperature Range -10 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 10 32 V
IOUT Output Current 0 2.5 A
TA Operating Ambient Temperature -10 85 oC
AP5004
PWM CONTROL 2.5A STEP-DOWN CONVERTER
AP5004
Document number: DS31444 Rev. 5 - 2 4 of 11
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© Diodes Incorporated
Electrical Characteristics (VIN = 12V, TA=25°C, unless otherwise specified)
Symbol Parameter Conditions Min Typ. Max Unit
VFB Feedback Voltage 0.780 0.8 0.820 V
VIN Input Voltage 10 - 32 V
ISTBY Standby Current VEN =0V - 2 - µA
∆VOUT/VOUT Line Regulation VIN = 10V~32V - ±1.0 ±1.5 %/V
∆VOUT/VOUT Load Regulation IOUT = 0.1 to 2.5A - 1 1.5 %
fOSC Oscillation Frequency Measure waveform at SW pin 240 300 360 KHz
fOSC1 Frequency of Current Limit or
Short Circuit Protect Measure waveform at SW pin - 50 - KHz
DC Maximum Duty Cycle VFB =0.5V - 90 - %
Minimum Duty Cycle VFB =1.0V - 0 - %
VIH EN Pin Logic Input Threshold
Voltage Regulator ON 2.0 - - V
VIL Regulator OFF - - 0.8
ISH EN Pin Input Leakage Current - 20 - µA
ISL - -10 - µA
RDS(ON) Internal MOSFET RDS
(
ON
)
- 80 120 mΩ
ILIMIT Current Limit 3.5 - - A
η Efficiency VIN = 12V, VOUT = 5V, IOUT = 2.5A - 90 - %
θJA Thermal Resistan ce Junction-
to-Ambient SOP-8L (Note 3) - 124 - oC/W
θJC Thermal Resistan ce Junction-
to-Case SOP-8L (Note 3) - 25 - oC/W
Notes: 3. Test condition for SOP-8L: Device mounted on 2oz copper, minimum recommended pad layout, FR-4 PCB.
AP5004
PWM CONTROL 2.5A STEP-DOWN CONVERTER
AP5004
Document number: DS31444 Rev. 5 - 2 5 of 11
www.diodes.com August 2010
© Diodes Incorporated
Typical Performance Characteristics
Load Regulation Line Regulation
0
0.2
0.4
0.6
0.8
1
1.2
0123
Iout(A)
Load Regulation(%)
0
0.3
0.6
0.9
1.2
1.5
0 4 8 121620242832
Vin(V)
Line Regulation(% )
Frequency vs. Vin Iccq vs. Vin
310
315
320
325
330
0 5 10 15 20 25 30 35
Vin(V)
Frequency(KHz)
Vout=5V;Iout=0.2A
7.05
7.1
7.15
7.2
7.25
7.3
7.35
7.4
7.45
0 5 10 15 20 25 30 35
Vin(V)
Quiescent Cur ren t(m A)
VFB=1V
Istandby vs. Vin
0
0.03
0.06
0.09
0.12
0.15
0 5 10 15 20 25 30 35
Vin(V)
Standby Current(uA)
VEN=0V
AP5004
PWM CONTROL 2.5A STEP-DOWN CONVERTER
AP5004
Document number: DS31444 Rev. 5 - 2 6 of 11
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© Diodes Incorporated
Typical Performance Characteristics (Continued)
Vout Ripple
(Vcc= 12V, Vout= 5V, Iout= 0A, Vripple= 19.0mV) Vout Ripple
(Vcc= 12V, Vout= 5V, Iout= 2.5A, Vripple= 35.0mV)
Load Transient Response
(Iout= 0.1~2.5A, Vin= 12V, Vout= 5V) Load Transient Response
(Iout= 0.1~2.5A, Vin= 32V, Vout= 5V)
AP5004
PWM CONTROL 2.5A STEP-DOWN CONVERTER
AP5004
Document number: DS31444 Rev. 5 - 2 7 of 11
www.diodes.com August 2010
© Diodes Incorporated
Test Circuit
A
FBVcc
GND
EN
open
open
FB
Vcc
GND
EN
+
-
Oscillation
OUTPUT OUTPUT
A
FB
Vcc
GND
EN
+
-+
-
V
OUTPUT
Vboost open
Vboost
Vboost
Enable function test Feedback function test
Operation function test
220uF
0.1uF
33uH
470uF
530 ohm
100 ohm
AP5004
PWM CONTROL 2.5A STEP-DOWN CONVERTER
AP5004
Document number: DS31444 Rev. 5 - 2 8 of 11
www.diodes.com August 2010
© Diodes Incorporated
Functional Description
PWM Control
The AP5004 consists of DC/DC converters that employ a pulse-width modulation (PWM) system. The PWM
controller is internally clocked by a fixed 300KHz oscillator.
When used as a converter, the AP5004’s pulse width varies in a range from 0% to 90%, 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.
Enable Control
The Enable Control allows the output of the AP5004 to be turned ON or OFF. Connecting the Enable pin to GND
or any voltage source lower than 0.8V will turn the output OFF. In the OFF state, the current drawn through the
VCC input is approximately 2µA. Please note that the slew rate from ON to OFF must be >0.013v/µs to ensure
proper operation.
BOOST Capacitor
This capacitor boosts the gate drive to the internal MOSFET above VIN to fully turn it ON thus minimizing
conduction losses in the power switch to maintain high efficiency. The recommended value of the capacitor is
0.1µF. The capacitor must be conne cte d from pin 3 to the switch output, pin 4.
Feedback
This is the input to a two-stage high gain amplifier, which drives the PWM controller. Two external resistors are
required to set the DC output voltage. For stable operation of the power supply, it is important to prevent coupling
of any inductor flux to the feedback inpu t.
Current Limit
The current limit threshold is set by the internal circuit such that the minimum switching current is 3.5A. If the
switching current exceeds the threshold, the output voltage will drop and the switching frequency will be reduced
to 50KHz.
Inductor Selection
Most designs operate with inductors of 15µH to 33µH. The inductor value can be derived from the following
equation:
(
)
IN
V
osc
f
L
IOUT
V
OUT
V
IN
V
L××Δ
−
=
Large value inductors will result in a lower ripple current where as small value inductors will result in high ripple
currents. The inductor ripple current should be set to approximately 15% of the maximum load current 2.5A,
∆IL=0.375A. The DC current rating of the inductor should be at least equal to the maximum load current plus half
the ripple current to prevent core saturation (2A+0.19A).
Input Capacitor Selection
The input current to the step-down converter is discontinuous, and therefore an input capacitor C2 is required to
supply the AC current to the step-down converter while maintaining the DC input voltage. A low ESR capacitor is
required to keep the noise at the IC to a minimum. Its RMS current rating should be greater than approximately
half of the DC load current.
AP5004
PWM CONTROL 2.5A STEP-DOWN CONVERTER
AP5004
Document number: DS31444 Rev. 5 - 2 9 of 11
www.diodes.com August 2010
© Diodes Incorporated
Functional Description (Continued)
Output Capacitor Selection
An output capacitor is required to maintain the DC output voltage. Low ESR capacitors are preferred to keep the
output voltage ripple low. The characteristics of the output capacitor also affect the stability of the regulation
control system. The ESR dominates the impedance at the switching frequency.The output ripple is calcul ated as:
ESR
RI
RIPPLE
V
×
Δ
≅
Output Rectifier Diode
The output rectifier diode supplies the current to the inductor when the high-side switch is OFF. To reduce losses
due to the diode forward voltage and recovery times, use a Schottky rectifier.
PCB Layout Guide
The dual Output pin (4) and VSS pins (7 & 8) on the SOP-8L package are internally connected to die pad. If low
TC & TJ or a large PD (Power Dissipation) is needed, the PCB layout should allow for maximum possible copper
area exposure at the SW pins. Please also follow the steps belo w to redu ce switching noise.
1. Connect C3 to VCC and VSS pin as closely as possible to get good power filter effect.
2. Connect ground side of the C2 & D1 as closely as possible.
Typical PC Board Layout:
Top Side Layout Guide Bottom Side Layout Guide
AP5004
PWM CONTROL 2.5A STEP-DOWN CONVERTER
AP5004
Document number: DS31444 Rev. 5 - 2 10 of 11
www.diodes.com August 2010
© Diodes Incorporated
Ordering Information
AP50 04 S G - 13
Package Packing
13 : Tape & Reel
Lead Free
G : Green
S : SOP-8L
Device Package
Code Packaging
(Note 4) 13” Tape and Reel
Quantity Part Number Suffix
AP5004SG-13 S SOP-8L 2500/Tape & Reel -13
Notes: 4. Pad layout as shown on Diodes Inc. suggested pad layout document AP02001, which can be found on our website at
http://www.diodes.com/datasheets/ap02001.pdf.
Marking Information
( Top View )
AP5004
YY WW
XX
Logo
Part Number
5
8
41
WW : Week : 01~52; 52
YY : Year : 08, 09,10~
G : Green
X : Internal Code
represents 52 and 53 week
Package Outline Dimensions (All Dimensions in mm)
1.27typ 0.3/0.5
7°~9°
4.85/4.95
3.85/3.95
5.90/6.10
0.15/0.25
7°~9°
0.62/0.82
0.10/0.20
Gauge Plane
0.254
Seating Plane
0.35max. 45°
Detail "A"
Detail "A"
1.30/1.50
1.75max.
Land Pattern Recommendation
(Unit: mm)
6x-1.27
8x-1.55
8x-0.60
5.4
0°/8°
AP5004
PWM CONTROL 2.5A STEP-DOWN CONVERTER
AP5004
Document number: DS31444 Rev. 5 - 2 11 of 11
www.diodes.com August 2010
© Diodes Incorporated
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