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AP1520
PWM CONTROL 2A STEP-DOWN CONVERTER
Features
* * * * * * * * * Input Voltage: 3.6V to 23V Output Voltage: 0.8V to VCC Duty Ratio: 0% to 100% PWM Control Oscillation Frequency: 300KHz typ. Soft-Start, Current Limit, Enable Function Thermal Shutdown Function Built-in Internal SW P-Channel MOS SOP-8L Pb-Free Package Lead Free Finish/RoHS Compliant (Note 1)
General Description
AP1520 consists of step-down switching regulator with PWM control. These devices include a reference voltage source, oscillation circuit, error amplifier, and internal PMOS. AP1520 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 overshooting 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 30KHz. 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 23V, 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
AP 1520 X X X Package S : SOP-8L Lead-Free L : Lead- Free Packing -U : Tube -13 : Taping
Note:
1. RoHS revision 13.2.2003. Glass and High Temperature Solder Exemptions Applied, see EU Directive Annex Notes 5 and 7.
Device (Note 2)
Lead-free
Package Packaging Code
S SOP-8L
Quantity
100/Tube
Tube Part Number Suffix
-U
13" Tape and Reel Quantity Part Number Suffix
2500/Tape & Reel -13
AP1520S
Note: 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.
AP1520 Rev. 1
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AP1520
PWM CONTROL 2A STEP-DOWN CONVERTER
Pin Assignments
( Top View ) FB 1 EN 2 AP1520 OCSET 3 VCC 4 SOP-8L 6 5 Output Output 8 7 Vss Vss
Pin Descriptions
Pin Pin Description Name No. FB 1 Feedback pin Power-off pin H: Normal operation EN 2 (Step-down operation) L: Step-down operation stopped (All circuits deactivated) Add an external resistor to set max OCSET 3 output current 4 IC power supply pin VCC Switch Pin. Connect external Output 5, 6 inductor/diode here. Minimize trace area at this pin to reduce EMI 7, 8 GND Pin VSS
Block Diagram
Output Oscillation Circuit Vcc PWM-Switched Control Circuit Thermal Shutdown VEN 100uA Vss + FB Reference Voltage Source with Soft Start
EN
OCSET
AP1520 Rev. 1
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AP1520
PWM CONTROL 2A STEP-DOWN CONVERTER
Absolute Maximum Ratings
Symbol VCC VFB VEN VOUT PD TOPR TSTG Parameter VCC Pin Voltage Feedback Pin Voltage EN Pin Voltage Switch Pin Voltage Power Dissipation Operating Temperature Range Storage Temperature Range Rating VSS - 0.3 to VSS + 25 VSS - 0.3 to VCC VSS - 0.3 to VIN + 0.3 VSS - 0.3 to VIN + 0.3 Internally limited -20 to +85 -40 to +150 Unit V V V V mW o C o C
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.
Electrical Characteristics
Symbol VIN VFB IFB ISW ISSS Parameter Input Voltage Feedback Voltage Feedback Bias Current Switch Current Current Consumption During Power off
( VIN = 12V, Ta = 25C, unless otherwise specified )
Conditions -IOUT = 0.1A IOUT = 0.1A -VEN = 0V VIN = 5V~23V IOUT = 0.1 to 2A Measure waveform at SW pin Measure waveform at SW pin Evaluate oscillation at SW pin Evaluate oscillation stop at SW pin ----VIN = 5V, VFB = 0V VIN = 12V, VFB = 0V VIN = 12V, VOUT = 5V IOUT = 2A
Min. 3.6 0.784 2.5 240 10 2.0 75 0.3 -
Typ. 0.8 0.1 10 1 0.2 300 20 -10 90 1 110 70 92 65
Max. 23 0.816 0.5 2 0.5 360 0.8 105 2 150 100 -
Unit V V A A A % % KHz KHz V A A A ms m %
o
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 IOCSET OCSET Pin Bias Current TSS Soft-Start Time RDSON Internal MOSFET RDSON EFFI JA Efficiency Thermal Resistance Junction-to-Ambient
C/W
AP1520 Rev. 1
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AP1520
PWM CONTROL 2A STEP-DOWN CONVERTER
Typical Application Circuit
VIN ROCSET COCSET 3K Option CIN 680uF CVcc 0.1uF REN 100K CEN 0.1uF
Vcc
Output
L1 22uH CC Optional RA 6.8K
VOUT
AP1520
OCSET EN VSS FB
+
C
+
COUT 470uF
- 0.1uF
D1* RB 1.3K
Note: VOUT = VFB x (1+RA/RB) RB=0.7K~5K ohm
VIN = 12V, IMAX = 2A 2.5V 3.3V 22uH 27uH
VOUT L1 Value
5V 33uH
*D1 = Diodes Inc. part number DFLS230L or SBR3U30P1.
Typical Performance Characteristics
AP1520 Vin vs. Frequency (Vout=3.3V; Iout=0.2A)
350 345 340
330 325 320 315 310
3.6 4 6 8 10 12 14 16 18
FB (V)
335
0.84 0.83 0.82 0.81 0.80 0.79 0.78 0.77 0.76 0.75 0.74 3.6
AP1520 Vin vs. FB (Vout=3.3V; Iout=0.2A)
Fosc (KHz)
Vin (V)
4
6
8
Vin (V)
10
12
14
16
18
AP1520 Rev. 1
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AP1520
PWM CONTROL 2A STEP-DOWN CONVERTER
Typical Performance Characteristics ( Continued )
AP1520 Line Regulation (Vin=12V; Iout=0.2A)
3.40 3.35
Vout (V)
3.25 3.20 3.15 3.10 3.6 4 6 8
Vout (A)
3.30
5.10 5.09 5.08 5.07 5.06 5.05 5.04 5.03 5.02 5.01 5.00 0.0
AP1520 Load Regulation (Vin=12V)
Vin (V)
10
12
14
16
18
1.0
2.0
3.0
4.0
Iout (A)
AP1520 Efficiency
100 90 80 70 60 50 40 30 20 10 0 0.0 0.5 1.0
Efficiency (%)
Vout:5.0V Vout:3.3V 1.5 2.0
Iout (A)
AP1520 Vout Ripple ( Vin = 12V; Vout = 3.3V; Iout = 0.1A )
AP1520 Vout Ripple ( Vin = 12V; Vout = 3.3V; Iout = 2A )
AP1520 Rev. 1
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AP1520
PWM CONTROL 2A STEP-DOWN CONVERTER
Test Circuit
Oscillation open VCC OUTPUT FB open
A +
VCC
OUTPUT
FB
OCSET
A
EN
VSS
-
OCSET EN
VSS
VCC
+ -
OUTPUT
FB
OCSET EN VSS
+ V
Function Description
PWM Control The AP1520 consists of DC/DC converters that employ a Pulse-Width Modulation (PWM) system. In converters of the AP1520, 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.
resumes once VCC rises above 3.5V.
RDS(ON) Current Limiting The current limit threshold is setting by the external resistor connecting from VCC supply to OCSET. The internal 100uA sink current crossing the resistor sets the voltage at the pin of OCSET. When the PWM voltage is less than the voltage at OCSET, an over-current condition is triggered.
ILOAD x RDS(ON) = IOCSET x ROCSET
Under Voltage Lockout The Under Voltage Lockout circuit of the AP1520 assures that the high-side MOSFET driver outputs remain in the off state whenever the supply voltage drops below 3.3V. Normal operation
See above formula for setting the current limit value.
AP1520 Rev. 1
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AP1520
PWM CONTROL 2A STEP-DOWN CONVERTER
Marking Information
(1) SOP-8L
( Top View )
8
5
Logo Part no. ID code: internal Xth week: 01~52 Year: "01" =2001 "02" =2002
AP1520 YY WW X
1
4
~
Device
AP1520S
Package
SOP-8L
Identification Code
AP1520
Package Information
Package Type: SOP-8L
( 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 7~9
0.35max. 45
Detail "A"
3.70/4.10
1.27typ 4.80/5.30
0.3/0.5
AP1520 Rev. 1
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(c) Diodes Incorporated
AP1520
PWM CONTROL 2A STEP-DOWN CONVERTER
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.
AP1520 Rev. 1
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