Information About LM2650 Evaluation Board Rev. printed circuit bo

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Information About LM2650 Evaluation Board Rev.
Information About LM2650 Evaluation Board Rev.
printed circuit board (PCB) been developed. This application note contains information about board.
National Semiconductor Application Note 1071 Steven Hunt October 1997
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.
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.
10001105
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.
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Figure through Figure show work.
2002 National Semiconductor Corporation
AN100011
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AN-1071
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 Compensation Components 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 37.4 3.57 k,C10 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 23.2
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TABLE Components Typical Application Circuits (Continued) Sleep Resistors RSIA RSOA RSIA RSOA 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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10001101
FIGURE LM2650 Evaluation Board Silk Screen (Scale 1:1)
10001102
FIGURE LM2650 Evaluation Board Bottom Silk Screen (Scale 1:1)
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10001103
FIGURE LM2650 Evaluation Board Component Side (Scale 1:1)
10001104
FIGURE LM2650 Evaluation Board Solder Side (Scale 1:1)
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Information About LM2650 Evaluation Board Rev.
Notes
LIFE SUPPORT POLICY NATIONAL'S PRODUCTS AUTHORIZED CRITICAL COMPONENTS LIFE SUPPORT DEVICES SYSTEMS WITHOUT EXPRESS WRITTEN APPROVAL PRESIDENT GENERAL COUNSEL NATIONAL SEMICONDUCTOR CORPORATION. used herein: Life support devices systems devices systems which, intended surgical implant into body, support sustain life, whose failure perform when properly used accordance with instructions provided labeling, reasonably expected result significant injury user. critical component component life support device system whose failure perform reasonably expected cause failure life support device system, affect safety effectiveness.
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National Semiconductor Japan Ltd. Tel: 81-3-5639-7560 Fax: 81-3-5639-7507
National does assume responsibility circuitry described, circuit patent licenses implied National reserves right time without notice change said circuitry specifications.

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