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AP65503

Document number: DS37127 Rev. 1 - 2

1 of 15

www.diodes.com

April 2014

P65503

LIGHT LOAD IMPROVED 5A, 750kHz SYNCH DC/DC BUCK CONVERTER

Description

The AP65503 is a 750kHz switching frequency external compensated

synchronous DC/DC buck converter. It has integrated low R

DSON

high

and low side MOSFETs.

The AP65503 enables continues load current of up to 5A with

efficiency as high as 96%.

The AP65503 implements an automatic custom light load efficiency

improvement algorithm.

The AP65503 features current mode control operation, which enables

fast transient response times and easy loop stabilization.

The AP65503 simplifies board layout and reduces space

requirements with its high level of integration and minimal need for

external components, making it ideal for distributed power

architectures.

The AP65503 is available in a standard Green SO-8EP package and

is RoHS compliant.

Features

• V

4.75V to 17V

• 5A Continuous Output Current, 7A Peak

• Efficiency Up to 96%

• Automated Light Load improvement

• V

OUT

Adjustable to 2.5 to 12V

• 750kHz Switching Frequency

• External Programmable Soft-Start

• Enable Pin

• OCP with Hiccup and Thermal Protection

• Totally Lead-Free & Fully RoHS Compliant (Notes 1 & 2)

• Halogen and Antimony Free. “Green” Device (Note 3)

Pin Assignments

Applications

• Gaming Consoles

• Flat Screen TV sets and Monitors

• Set Top Boxes

• Distributed power systems

• Home Audio

• Consumer electronics

• Network Systems

• FPGA, DSP and ASIC Supplies

• Green Electronics

Notes: 1. No purposely added lead. Fully EU Directive 2002/95/EC (RoHS) & 2011/65/EU (RoHS 2) compliant.

2. See http://www.diodes.com/quality/lead_free.html for more information about Diodes Incorporated’s definitions of Halogen- and Antimony-free, "Green"

and Lead-free.

3. Halogen- and Antimony-free "Green” products are defined as those which contain <900ppm bromine, <900ppm chlorine (<1500ppm total Br + Cl) and

<1000ppm antimony compounds.

Typical Applications Circuit

Figure 1 Typical Application Circuit

Summary of content (15 pages)

PAGE 1
AP65503 LIGHT LOAD IMPROVED 5A, 750kHz SYNCH DC/DC BUCK CONVERTER Description Pin Assignments The AP65503 is a 750kHz switching frequency external compensated synchronous DC/DC buck converter. It has integrated low RDSON high and low side MOSFETs. The AP65503 enables continues load current of up to 5A with efficiency as high as 96%. The AP65503 implements an automatic custom light load efficiency improvement algorithm.
PAGE 2
AP65503 Pin Descriptions Pin Name Pin Number BS 1 IN 2 SW 3 GND 4 FB 5 COMP 6 EN 7 SS 8 EP EP Function High-Side Gate Drive Boost Input. BS supplies the drive for the high-side N-Channel MOSFET a 0.01µF or greater capacitor from SW to BS to power the high side switch. Power Input. IN supplies the power to the IC, as well as the step-down converter switches. Drive IN with a 4.75V to 17V power source.
PAGE 3
AP65503 Absolute Maximum Ratings (Note 4) (@TA = +25°C, unless otherwise specified.) Symbol Parameter VIN Supply Voltage VSW Switch Node Voltage VBS Unit -0.3 to 20 V -1.0 to VIN +0.3 V Bootstrap Voltage VSW -0.3 to VSW +6.0 V VFB Feedback Voltage -0.3V to +6.0 V VEN Enable/UVLO Voltage -0.3V to +6.0 V Comp Voltage -0.3V to +6.0 V Storage Temperature -65 to +150 °C TJ Junction Temperature +160 °C TL Lead Temperature +260 °C 1.
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AP65503 Electrical Characteristics (@TA = +25°C, VIN = 12V, unless otherwise specified.) Symbol Parameter Test Conditions Min Typ Max Unit Shutdown Supply Current VEN = 0V — 0.3 3.0 µA Supply Current (Quiescent) VEN = 2.0V, VFB = 1.0V — 0.3 1.
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AP65503 Typical Performance Characteristics (@TA = +25°C, VIN = 12V, VOUT = 3.3V, unless otherwise specified.) AP65503 Document number: DS37127 Rev. 1 - 2 5 of 15 www.diodes.
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AP65503 Typical Performance Characteristics (cont.) (@TA = +25°C, VIN = 12V, VOUT = 3.3V, unless otherwise specified.) AP65503 Document number: DS37127 Rev. 1 - 2 6 of 15 www.diodes.
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AP65503 Typical Performance Characteristics (cont.) (@TA = +25°C, VIN = 12V, VOUT = 3.3V, L = 4.7µH, C1 = 44µF, C2 = 72µF, unless otherwise specified.) Steady State Test 5A Startup Through Vin No Load Startup Through Vin 5A Load Time-2µs/div Time-5ms/div Time-5ms/div Load Transient Test 2.5 to 5A Shutdown Through Vin no load Shutdown Through Vin 5A Load Time-2ms/div Time-200ms/div Time-100ms/div Short Circuit Test Short Circuit Recovery Load Transient Test 2.
PAGE 8
AP65503 Application Information Theory of Operation The AP65503 is a 5A current mode control, synchronous buck regulator with built in power MOSFETs. Current mode control assures excellent line and load regulation and a wide loop bandwidth for fast response to load transients. The Figure 1 depicts the functional block diagram of AP65503. The operation of one switching cycle can be explained as follows. At the beginning of each cycle, HS (high-side) MOSFET is off.
PAGE 9
AP65503 Application Information (cont.) Current Limit Protection In order to reduce the total power dissipation and to protect the application, AP65503 has cycle-by-cycle current limiting implementation. The voltage drop across the internal high-side MOSFET is sensed and compared with the internally set current limit threshold. This voltage drop is sensed at about 30ns after the HS turns on. When the peak inductor current exceeds the set current limit threshold, current limit protection is activated.
PAGE 10
AP65503 Application Information (cont.) Compensation Components The AP65503 has an external COMP pin through which system stability and transient response can be controlled. COMP pin is the output of the internal trans-conductance error amplifier. A series capacitor-resistor combination sets a pole-zero combination to control the characteristics of the control system. The DC gain of the voltage feedback loop is given by: A VDC = RLOAD × GCS × A VEA × VFB VOUT Where VFB is the feedback voltage (0.
PAGE 11
AP65503 Application Information (cont.) Inductor (cont.) Choose the inductor ripple current to be 30% of the maximum load current. The maximum inductor peak current is calculated from: IL(MAX) = ILOAD + ∆I L 2 Peak current determines the required saturation current rating, which influences the size of the inductor. Saturating the inductor decreases the converter efficiency while increasing the temperatures of the inductor and the internal MOSFETs.
PAGE 12
AP65503 Application Information (cont.) PC Board Layout This is a high switching frequency converter. Hence attention must be paid to the switching currents interference in the layout. Switching current from one power device to another can generate voltage transients across the impedances of the interconnecting bond wires and circuit traces. These interconnecting impedances should be minimized by using wide, short printed circuit traces.
PAGE 13
AP65503 Ordering Information Part Number Package Code Part Marking Identification Code AP65503SP-13 SP SO-8EP NA Note: Tape and Reel Quantity Part Number Suffix 2500 -13 9. For packaging details, go to our website at http://www.diodes.com/products/packages.html Marking Information SO-8EP AP65503 Document number: DS37127 Rev. 1 - 2 13 of 15 www.diodes.
PAGE 14
AP65503 Package Outline Dimensions (All dimensions in mm.) Please see AP02002 at http://www.diodes.com/datasheets/ap02002.pdf for latest version. SO-8EP Exposed Pad 8 5 E1 1 H 4 F b Bottom View 9° (All sides) N 7° A e D E 45° Q 4° ± 3° E0 A1 C Gauge Plane Seating Plane L SO-8EP (SOP-8L-EP) Dim Min Max Typ A 1.40 1.50 1.45 A1 0.00 0.13 b 0.30 0.50 0.40 C 0.15 0.25 0.20 D 4.85 4.95 4.90 E 3.80 3.90 3.85 E0 3.85 3.95 3.90 E1 5.90 6.10 6.00 e 1.27 F 2.75 3.35 3.05 H 2.11 2.71 2.41 L 0.62 0.
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AP65503 IMPORTANT NOTICE DIODES INCORPORATED MAKES NO WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, WITH REGARDS TO THIS DOCUMENT, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE (AND THEIR EQUIVALENTS UNDER THE LAWS OF ANY JURISDICTION). Diodes Incorporated and its subsidiaries reserve the right to make modifications, enhancements, improvements, corrections or other changes without further notice to this document and any product described herein.