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AP5002
PWM CONTROL 2A STEP-DOWN CONVERTER
Features
* * * * * * * * * * * Input voltage: 3.6V to 20V Output voltage: 0.8V to VCC Duty ratio: up to 100% PWM control Oscillation frequency: 500KHz typical Soft-start Current Limit, Enable function Thermal Shutdown function Built-in internal SW P-channel MOS Low ESR output capacitor (MLCC, multi-layer ceramic capacitor) support Efficiency 90% SOP-8L: Available in "Green" Molding Compound (No Br, Sb) Lead Free Finish / RoHS Compliant (Note 1)
General Description
AP5002 consists of step-down switching regulator with PWM control. These devices include a reference voltage source, oscillation circuit, error amplifier, internal PMOS. AP5002 provides low-ripple power, high efficiency, and excellent transient characteristics. The PWM control circuit is able to vary the duty ratio linearly 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. 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 22V, it is also suitable for the operation via an AC adapter.
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
Ordering Information
AP5002 S G - X Package S : SOP-8L Lead Free G : Green Packing U : Tube 13 : Taping & Reel
13" Tape and Reel Part Number Quantity Suffix NA NA 2500/Tape & Reel -13
Device AP5002SG-U AP5002SG-13
Notes:
Package Code S S
Packaging (Note 2) SOP-8L SOP-8L
Tube Part Number Quantity Suffix 100 -U NA NA
1. EU Directive 2002/95/EC (RoHS). All applicable RoHS exemptions applied, see EU Directive 2002/95/EC Annex Notes. 2. 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.
AP5002 Rev. 6
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AP5002
PWM CONTROL 2A STEP-DOWN CONVERTER
Pin Assignments
( Top View ) FB 1 EN 2 AP5002 Comp 3 VCC 4 SOP-8L 6 5 Output Output 8 7 Vss Vss
Pin Descriptions
Name Pin FB 1 Description Feedback pin Power-off pin H: Normal operation 2 (Step-down operation) L: Step-down operation stopped (All circuits deactivated) 3 Compensation pin 4 IC power supply pin Switch Pin. Connect external 56 inductor/diode here. Minimize trace area at this pin to reduce EMI. 78 GND Pin
EN
Comp VCC Output VSS
Block Diagram
Output Oscillation Circuit Vcc PWM-Switched Control Circuit Thermal Shutdown 100uA VEN Vss
+
Reference Voltage Source
FB
-
EN
Comp
AP5002 Rev. 6
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AP5002
PWM CONTROL 2A STEP-DOWN CONVERTER
Absolute Maximum Ratings
Symbol ESD MM VCC VFB VEN VOUTPUT PD TJ TST Parameter Machine Model ESD Protection VCC Pin Voltage Feedback Pin Voltage EN Pin Voltage Switch Pin Voltage Power Dissipation Operating Junction Temperature Range Storage Temperature Range Rating 5 200 VSS - 0.3 to VSS + 22 VSS - 0.3 to VCC VSS - 0.3 to VIN VSS - 0.3 to VIN 1000 -20 to +125 -65 to +150 Unit KV V V V V V mW o C o C
ESD HBM Human Body Model ESD Protection
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 VIN IOUT TA Parameter Input Voltage Output Current Operating Ambient Temperature Min 3.6 0 -20 Max 20 2 85 Unit V A o C
AP5002 Rev. 6
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AP5002
PWM CONTROL 2A STEP-DOWN CONVERTER
Electrical Characteristics
Symbol VFB IFB ICCQ ISW ISD VOUT /VOUT VOUT /VOUT fOSC VSH VSL ISH ISL TSS RDSON Parameter Feedback Voltage Feedback Bias Current Quiescent Current Switch Current Shutdown Supply Current Line Regulation Load Regulation Oscillation Frequency EN Pin Input Voltage EN Pin Input Leakage Current Soft-Start Time Internal MOSFET Rdson Thermal shutdown Minimum Duty Cycle JA JC
Notes:
(VIN = 12V, TA = 25C, unless otherwise specified)
Conditions IOUT = 0.1A IOUT = 0.1A VFB = 1.2 force drive off -VEN = 0V VIN = 4V~20V, IOUT = 0.2A IOUT = 0.1 to 2A Measure waveform at SW pin Evaluate oscillation at SW pin Evaluate oscillation stop at SW pin Ven = 2V Ven = 0.8V -VIN = 5V, VFB = 0V VIN = 12V, VFB = 0V
Min 0.784 3.5 400 2.0 -10 -10 -
Typ. 0.8 0.1 3 10 1 0.5 500 3 110 70 140 6.5
Max 0.816 0.5 5 2 1 600 0.8 10 10 150 100
Unit V A mA A A % % KHz V A A ms m
o
C
%
o
Thermal Resistance Junction-to-Ambient Thermal Resistance Junction-to-Case
SOP-8L (Note 3) SOP-8L (Note 3)
124 25
C/W C/W
o
3. Test condition: Device mounted on 2oz copper, minimum recommended pad layout, FR-4 PCB.
AP5002 Rev. 6
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AP5002
PWM CONTROL 2A STEP-DOWN CONVERTER
Typical Application Circuit
VIN+12V ON/OFF
U1 1 R5 100K 2 3 C6 0.1uF 4 FB EN COMP VCC AP5002 R2 1.2K VSS VSS Output Output 8 7 6 5 1
C2 22uF
C3 0.1uF
L1-(WURTH S05100104) 10uH 2 R1 3.8K C1 330pF
VOUT = 3.3V
D1 Dii 723 B340A
C8 0.1uF
C4 22uF
R4 0.8~2K
C7 0.1uF
Compensation Capacitor Selection(MLCC) VIN 12V 5V VOUT 5/ 3.3/ 2.5/ 1.8/ 1.5V 3.3/ 2.5/ 1.8/ 1.5V R4 0.8~2K 0.8~2K C7 0.1F 27nF C1 330pF 330pF
VIN+12V 1 R5 100K ON/OFF 2 3 C6 0.1uF 4
U1 FB EN COMP VCC AP5002 VSS VSS Output Output 8 7 6 5 1 D1 Dii 723 B340A
L1-(WURTH S05100104) 10uH
2 R1 3.8K C1 330pF
VOUT = 3.3V
C2 470uF
C3 0.1uF
C8 0.1uF
C4 470uF
R4 4.7~6.8K
C7 33nF
R2 1.2K
Notes:
4.
VOUT = VFB x (1+
R1 R2
)
AP5002 Rev. 6
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AP5002
PWM CONTROL 2A STEP-DOWN CONVERTER
Typical Performance Characteristics
AP5002 Temperature vs. Frequency (Vout=3.3V; Iout=0.2A)
575
Frequency(KHZ)
570
Frequency(KHZ)
AP5002 Vin vs. Frequency (Vout=3.3V; Iout=0.2A)
560 550 540 530 520 510 0 5 10 Vin(V) 15 20 25
560 545 530 515 500 485 -20 0 20 40 60 Temperature( ) 80 100 120
0.808 0.806
VFB(V)
AP5002 Vin vs. FB (Vout=3.3V; Iout=0.2A)
AP5002 Temperature vs. FB (Vout=3.3V; Iout=0.2A)
0.82
0.81
0.804 0.802 0.8 0 5 10 15 Vin(V) 20 25
VFB(V)
0.8
0.79
0.78 -20 30 80 Temperature( ) 130
AP5002 Efficiency
100 90 80 70
Efficiency(%)
Vout=5V Vout=3.3V
60 50 40 30 20 10 0 0 0.5
1 Iout(A)
1.5
2
AP5002 Rev. 6
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AP5002
PWM CONTROL 2A STEP-DOWN CONVERTER
Typical Performance Characteristics
(Continued)
AP5002 Load Regulation
3.35 3.34
3.35 3.34 3.33 3.32 3.31 3.3 0
AP5002 Line Regulation
Vout(V)
3.32 3.31 3.3 0 0.5 1 Iout(A) 1.5 2
Vout(V)
3.33
5
10
Vin(V)
15
20
25
AP5002 Vin vs. I CCQ (Vout=3.3V)
5 4
ICCQ(mA)
5 4.5 4 3.5 3 2.5 2 1.5 1 0.5 0 -20
AP5002 Temperature vs. I CCQ (Vout=3.3V)
3 2 1 0 0 5 10 Vin(V) 15 20
ICCQ(mA)
0
20 40 60 Temperature( )
80
100
120
AP5002 Rev. 6
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AP5002
PWM CONTROL 2A STEP-DOWN CONVERTER
Typical Performance Characteristics
AP5002 Vout Ripple (Vin=12V; Vout=5V; Iout=0.2A)
(Continued)
AP5002 Vout Ripple (Vin=12V; Vout=5V; Iout=2A)
Test Circuit
Oscillation open VCC OUTPUT FB open
A
VCC
OUTPUT
FB
COMP
A
+
EN
VSS
-
COMP EN
VSS
Enable function test
22u
Feedback function test
VCC
+ -
OUTPUT
FB
6.8K 1500p 6.8K
+ V
COMP EN VSS
1.2K
Operation function test
AP5002 Rev. 6
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AP5002
PWM CONTROL 2A STEP-DOWN CONVERTER
Functional Description
PWM Control The AP5002 consists of DC/DC converters that employ a pulse-width modulation (PWM) system. In converters of the AP5002, the pulse width varies in a range up 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. RDS(ON) Current Limiting The current limit threshold is set by the internal circuit. Setting the Output Voltage Application circuit item shows the basic application circuit with adjustable output version. The external resistor sets the output voltage according to the following equation: VOUT (V) 5 3.3 2.5 1.8 1.5 1.2 1 R1 (K) 6.4 3.8 2.6 3.3 3.3 3.3 3.3 R2 (K) 1.2 1.2 1.2 2.6 3.7 6.5 13 value. For the output capacitor, the ESR value is the most important parameter. The output ripple can be calculated from the following formula.
VRIPPLE = IL x ESR
The bulk capacitor's ESR will determine the output ripple voltage and the initial voltage drop after a high slew-rate transient. An aluminum electrolytic capacitor's ESR value is related to the capacitance and its voltage rating. In most case, higher voltage electrolytic capacitors have lower ESR values. Most of the time, capacitors with much higher voltage ratings may be needed to provide the low ESR values required for low output ripple voltage. MLCC CAP A 22F MLCC capacitor for most applications is sufficient. PCB Layout Guide If you need low TC & TJ or large PD(Power Dissipation), The dual SW pins(5& 6) and VSS pins(7& 8)on the SOP-8L package are internally connected to die pad, The PCB layout should allow for maximum possible copper area at the SW pins. 1. Connect C3 to VCC and VSS pin as closely as possible to get good power filter effect. 2. Connect R4 to VCC and OCSET pin as closely as possible. 3. Connect ground side of the C2 & D1 as closely as possible. Typical PC Board Layout Top Side Layout Guide
Inductor Selection For most designs, the operates with inductors of 10H to 22H. The inductor value can be derived from the following equation:
L=
(VIN
- VOUT )TON 2 x I L x f osc
Where is inductor Ripple Current. Large value inductors lower ripple current and small value inductors result in high ripple currents. Choose inductor ripple current approximately 15% of the maximum load current 2A, IL=0.3A. 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+0.15A). Input Capacitor Selection EL CAP This capacitor should be located close to the IC using short leads and the voltage rating should be approximately 1.5 times the maximum input voltage. The RMS current rating requirement for the input capacitor of a buck regulator is approximately 12 the DC load current. A low ESR input capacitor sized for maximum RMS current must be used. A 470F low ESR capacitor for most applications is sufficient. MLCC CAP A 22F MLCC capacitor for most applications is sufficient. Output Capacitor Selection EL CAP The output capacitor is required to filter the output voltage and provides regulator loop stability. The important capacitor parameters are the 100KHz Equivalent Series Resistance (ESR), the RMS ripples current rating, voltage rating and capacitance Use vias to conduct the heat into the backside of PCB layer. The PCB heat sink copper area should be solder-painted without masked. This approaches a Bottom Side Layout Guide
AP5002 Rev. 6
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AP5002
PWM CONTROL 2A STEP-DOWN CONVERTER
Marking Information
(Top view) 8 Logo Part Number 7 6 5
AP5002
YY XX X X
G : Green Internal Code Xth week: 01~52 Year: "07" = 2007 "08" = 2008
~
1
2
3
4
SOP-8L
Package Information
(All Dimensions in mm)
3.70/4.10
5.79/6.20
0.08/0.25
0.254 0.38/1.27
Gauge Plane Seating Plane
Detail "A"
7~9 1.30/1.50 1.75max. 0.20typ
0.35max. 45
7~9
Detail "A"
3.70/4.10
1.27typ 4.80/5.30
0.3/0.5
0.78
8x-0.60 5.4 6x-1.27 8x-1.55
Land Pattern Recommendation (Unit: mm)
IMPORTANT NOTICE 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. LIFE SUPPORT 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.
AP5002 Rev. 6
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