Information About LM2650 Evaluation Board Rev. INTRODUCTION print

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Information About LM2650 Evaluation Board Rev. INTRODUCTION print

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Information About LM2650 Evaluation Board Rev.
Information About LM2650 Evaluation Board Rev.
INTRODUCTION printed circuit board (PCB) been developed. This application note contains information about board. GENERAL DESCRIPTION LM2650 evaluation board provided tool developing DC/DC converters based LM2650 configured single-output, step-down DC/DC converters. Figure complete schematic board which accommodate components including LM2650. Table complete list pads placing components. Note: applications will require placement components. number components placed depends requirements application features like programmable soft-start. LM2650 evaluation board intended reusable tool which many different converters meeting requirements many different applications built. intended demonstrate only application LM2650.
National Semiconductor AN-1071 Steven Hunt September 1997
convenience, sample LM2650 eight other components have been assembled: capacitor each capacitor CVDD, 0.01 capacitor CSS, 24.9 resistor resistor eight, first seven common many applications, last simply jumper grounding SYNC input. When synchronization feature being used, SYNC input should grounded. EXAMPLE CIRCUITS components contained Tables used build typical application circuits. with design DC/DC converter, design these involved tradeoffs between efficiency, size, cost. converters detailed Table were designed with efficiency number criteria. Those detailed Table trade slightly higher switching losses much smaller inductor.
AN100011-5
FIGURE LM2650 Evaluation Board Rev. Schematic THERMAL PERFORMANCE 24-lead package molded plastic package with solid copper lead frame. Most heat generated flows through lead frame into 3-ounce copper planes board. board then acts heat sink. junction-to-ambient thermal resistance packaged mounted board been measured 38°C/W, °C/W, °C/W dissipation 1.0W, 1.5W, 2.0W respectively. These measurements were made still air. junction-to-ambient thermal resistance packaged alone still 78°C/W. board 0.063 thick FR-4 material. Figure through Figure show work.
AN-1071
1997 National Semiconductor Corporation
AN100011
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TABLE Complete List Pads Placing Components Label placing LM2650. Capacitors placed here filter high-frequency switching noise from input power rail. These pads should labeled with component placed here. They used ground SLEEP LOGIC input. connected SLEEP LOGIC used pull input capacitor placed here also filters high-frequency switching noise from input power rail rail, rail used signal-level circuits inside Usually component placed here. capacitor might placed here loop compensation purposes, most applications don't capacitor placed here loop compensation purposes. bootstrap capacitor placed here. capacitor placed here loop compensation purposes. This capacitor internal resistor create integrator pole. bulk input capacitors placed here. output filter capacitors placed here. capacitor placed here programs soft-start interval. capacitor placed here bypasses output regulator. inductor placed here. feedback resistors placed here. other feedback resistor placed here. resistor placed here loop compensation purposes. These pads used ground SYNC input when synchronization feature being used. connected SYNC input used connect synchronization signal. evaluation board jumper placed here ground SYNC input. resistor also placed here loop compensation purposes. This resistor capacitor placed create integrator zero. resistor placed here adjusts switching frequency from nominal kHz. component placed here applications switching kHz. Resistors placed here program sleep-in threshold. Resistors placed here program sleep-out threshold. Notes
CIN1 CIN2 COUT1, COUT2, COUT3 CVDD
RSIA RSIC RSOA RSOC
TABLE Components Typical Application Circuits Input Voltage Applicable Cell Stacks Output Input Filter Capacitors Bootstrap Capacitor Soft-start Capacitor Bypass Capacitor CVDD Input Bulk Capacitors CIN1 CIN2 Inductor Output Capacitors COUT1, COUT2, COUT3 Feedback Resistors ceramic chip capacitor ceramic chip capacitor 0.01 ceramic chip capacitor ceramic chip capacitor Series Sprague 593D Series tantalum chip capacitor (See Table Series Sprague 593D Series tantalum chip capacitor 24.9 12-Cell NiCd NiMH, 4-Cell Ion, 11-Cell Alkaline, 6-Cell Lead Acid 3.3V, ceramic chip capacitor ceramic chip capacitor 0.01 ceramic chip capacitor ceramic chip capacitor Series Sprague 593D Series tantalum chip capacitor (See Table Series Sprague 593D Series tantalum chip capacitor 41.2 24.9
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TABLE Components Typical Application Circuits (Continued) Compensation Components Sleep Resistors RSIA RSOA 37.4 3.57 k,C10 RSIA RSOA 23.2 RSIA RSOA
TABLE Toroidal Inductors Using Cores from MICROMETALS, INC. Core T50(B) Core Material Wire Gauge Strands Turns
TABLE Components Typical Application Circuits Input Voltage Applicable Cell Stacks Output Input Filter Capacitors Bootstrap Capacitor Soft-start Capacitor Bypass Capacitor CVDD Input Bulk Capacitors CIN1 CIN2 Inductor Output Capacitors COUT1, COUT2, COUT3 Feedback Resistors Compensation Components Sleep Resistors RSIA RSOA Frequency Adjusting Resistor ceramic chip capacitor ceramic chip capacitor 0.01 ceramic chip capacitor ceramic chip capacitor Series Sprague 593D Series tantalum chip capacitor (See Table Series Sprague 593D Series tantalum chip capacitor 24.9 53.6 4.02 RSIA RSOA 24.9 12-Cell NiCd NiMH, 4-Cell Ion, 11-Cell Alkaline, 6-Cell Lead Acid 3.3V, ceramic chip capacitor ceramic chip capacitor 0.01 ceramic chip capacitor ceramic chip capacitor Series Sprague 593D Series tantalum chip capacitor (See Table Series Sprague 593D Series tantalum chip capacitor 41.2 24.9 33.2 3.01 RSIA RSOA 24.9
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AN100011-1
FIGURE LM2650 Evaluation Board Silk Screen (Scale 1:1)
AN100011-2
FIGURE LM2650 Evaluation Board Bottom Silk Screen (Scale 1:1)
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AN100011-3
FIGURE LM2650 Evaluation Board Component Side (Scale 1:1)
AN100011-4
FIGURE LM2650 Evaluation Board Solder Side (Scale 1:1)
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Information About LM2650 Evaluation Board Rev.
LIFE SUPPORT POLICY NATIONAL'S PRODUCTS AUTHORIZED CRITICAL COMPONENTS LIFE SUPPORT DEVICES SYSTEMS WITHOUT EXPRESS WRITTEN APPROVAL PRESIDENT NATIONAL SEMICONDUCTOR CORPORATION. used herein: critical component component life support Life support devices systems devices device system whose failure perform systems which, intended surgical implant reasonably expected cause failure life into body, support sustain life, support device system, affect safety whose failure perform when properly used effectiveness. accordance with instructions provided labeling, reasonably expected result significant injury user.
AN-1071
National Semiconductor Corporation Americas Tel: 1-800-272-9959 Fax: 1-800-737-7018 Email: support@nsc.com
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National does assume responsibility circuitry described, circuit patent licenses implied National reserves right time without notice change said circuitry specifications.

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