Designing Switching Voltage Regulators with …

1 Application ReportSLVA143 - September 20031 Designing Switching Voltage Regulators with TL497 AJohn Spencer and Eugene J. TobabenLinear Products DepartmentABSTRACTS witching Voltage Regulators , represented by the TL497, can achieve high-efficiency powerconversion at large input/output Voltage differentials. The tl497a eliminates complex circuitdesigns previously required and provides greater efficiency than systems using series passregulators. The principle of operation is discussed, and practical design exercises forstep-down, step-up, and inverting Regulators are .. Principle of Operation3.. The TL497A3.. General3.. Programming4.. Oscillator4.. Current Limiting5.. Pass Transistor5.. Catch Diode5.. Enable Circuitry5.. Design and Operation of a Step-Down Switching Voltage Regulator6.. Summary8.. A Step-Down Switching Regulator Design Exercise with TL497A9.. Design and Operation of a Step-Up Switching Voltage Regulator13.. A Step-Up Switching Regulator Design Exercise with TL497A14.

2 Design and Operation of Switching Voltage Regulator in Inverting Configuration16.. An Inverting Regulator Design Exercise with TL497A17.. Special tl497a Circuits18.. Design Variations For Improved Performance19.. Extended Voltage Operation21.. Low Voltage Operation21.. Switching Regulator Design Tips21.. Inductor Sources22.. Appendix23.. List of FiguresFigure Switching Voltage Regulator3.. Figure Block Diagram4.. SLVA1432 Designing Switching Voltage Regulators with TL497 AFigure Voltage Waveform4.. Figure Ct Voltage Waveform During Start-Up and Quiescent Operation5.. Figure Voltage Waveform5.. Figure Step-Down Regulator6.. Figure Current Waveform6.. Figure Current and Capacitor Current Waveform7.. Figure Current Waveform ( Q+)7.. Figure Current Waveform ( Q )7.. Figure Current Waveform (Continuous Mode)8.. Figure Step-Down Regulator9.. Figure Volt to 5 Volt Switching Regulator for Output Currents to 200 mA10.. Figure Performance Waveforms10.

3 Figure for Obtaining Peak Currents Greater Than 500 mA10.. Figure in High- Voltage -High-Current Applications11.. Figure Logic Array Power Supply, Step-Down Circuit12.. Figure Regulator12.. Figure Step-Up Regulator Circuit13.. Figure and Capacitor Step-Up Regulator13.. Figure Step-Up Regulator Using the TL497A14.. Figure Volt to 15 Volt Switching Regulator15.. Figure Step-Up Circuit, 5V Input to 12V @ 80 mA Output15.. Figure Inverting Regulator Circuit16.. Figure Inverting Regulator17.. Figure 26.+5 Volt to 5 Volt Switching Regulator18.. Figure to Step-Up/Down Circuit18.. Figure Dual Supply +12 Volts and 12 Volts From +5 Volts18.. Figure Regulator Architectures19.. Figure 30(a). Step-Down Regulator19.. Figure 30(b). tl497a with External PNP Switch For Improved Performance19.. Figure Waveforms19.. Figure Regulator with Feedback Diodes20.. Figure .. Figure .. Figure .. List of TablesTable Operation From a 5V Supply24.

4 Table Operation From a 12V Supply24.. SLVA1433 Designing Switching Voltage Regulators with TL497 ASLVA1434 Designing Switching Voltage Regulators with TL497 ASLVA1435 Designing Switching Voltage Regulators with TL497 ASLVA1436 Designing Switching Voltage Regulators with TL497 ASLVA1437 Designing Switching Voltage Regulators with TL497 ASLVA1438 Designing Switching Voltage Regulators with TL497 ASLVA1439 Designing Switching Voltage Regulators with TL497 ASLVA14310 Designing Switching Voltage Regulators with TL497 ASLVA14311 Designing Switching Voltage Regulators with TL497 ASLVA14312 Designing Switching Voltage Regulators with TL497 ASLVA14313 Designing Switching Voltage Regulators with TL497 ASLVA14314 Designing Switching Voltage Regulators with TL497 ASLVA14315 Designing Switching Voltage Regulators with TL497 ASLVA14316 Designing Switching Voltage Regulators with TL497 ASLVA14317 Designing Switching Voltage Regulators with TL497 ASLVA14318 Designing Switching Voltage

5 Regulators with TL497 ASLVA14319 Designing Switching Voltage Regulators with TL497 ASLVA14320 Designing Switching Voltage Regulators with TL497 ASLVA14321 Designing Switching Voltage Regulators with tl497a *NOTE: See the next page for possible inductor Switching Voltage Regulators with TL497 ASLVA14323 Designing Switching Voltage Regulators with TL497 ASLVA14324 Designing Switching Voltage Regulators with TL497 AIMPORTANT NOTICET exas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, modifications,enhancements, improvements, and other changes to its products and services at any time and to discontinueany product or service without notice. Customers should obtain the latest relevant information before placingorders and should verify that such information is current and complete. All products are sold subject to TI s termsand conditions of sale supplied at the time of order warrants performance of its hardware products to the specifications applicable at the time of sale inaccordance with TI s standard warranty.

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