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User’s Guide
June 1999 Mixed-Signal Linear Products
SLVU013
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IMPORTANT NOTICE Texas Instruments and its subsidiaries (TI) reserve the right to make changes to their products or to discontinue any product or service without notice, and advise customers to obtain the latest version of relevant information to verify, before placing orders, that information being relied on is current and complete. All products are sold subject to the terms and conditions of sale supplied at the time of order acknowledgement, including those pertaining to warranty, patent infr
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Information About Cautions and Warnings Preface Read This First About This Manual This user’s guide describes techniques for designing synchronous buck converters using TI’s SLVP1111–114 evaluation modules (EVM) and TPS56xx ripple regulator controllers. How to Use This Manual This document contains the following chapters: Chapter 1 Introduction Chapter 2 Design Procedure Chapter 3 Test Results Information About Cautions and Warnings This book may contain cautions and warnings. This is an
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Trademarks Related Documentation From Texas Instruments Synchronous Buck Converter Design Using TPS56xx Controllers in SLVP10x EVMs User’s Guide (literature number SLVU007). TPS56xx data sheet (literature number SLVS177A) Designer’s Notebook The TPS56xx Family of Power Supply Controllers (literature number SLVT140A) Designing Fast Response Synchronous Buck Regulators Using the TPS5210 (literaure number SLVA044). FCC Warning This equipment is intended for use in a laboratory test environ
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Running Title—Attribute Reference Contents 1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1 1.1 Synchronous Buck Regulator Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2 1.2 Hysteretic Control Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3 1.3 Design Strategy . . . . . . . . . . .
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Running Title—Attribute Reference Figures 1–1 Simplified Synchronous Buck Converter Schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2 1–2 Simplified Hysteretic Controlled Output Voltage Waveform . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3 1–3 SLVP111–114 EVM Converter Schematic Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-7 1–4 Top Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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Running Title—Attribute Reference 3–27 SLVP113 Measured Start-Up (V ) Waveforms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-19 IN 3–28 SLVP113 Measured Load Transient Waveforms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-20 3–29 SLVP114 Measured Load Regulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-20 3–30 SLVP114 Measured Efficiency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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Chapter 1 Introduction The SLVP111/112/113/114 evaluation modules (EVMs) have been designed and tested using the TPS56xx hysteretic controllers. These boards are synchronous dc-dc buck converters with fixed output voltages of 3.3 V, 2.5 V, 1.8 V and 1.5 V respectively. They use only surface mount components and are design examples of how to use TI’s TPS56xx controllers in high density, low loss applications with tight static and dynamic output voltage requirements. Detailed test results taken
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Synchronous Buck Regulator Operation 1.1 Synchronous Buck Regulator Operation The synchronous buck converter is a variation of the traditional buck converter. The main switching device is usually a power MOSFET and is driven in the same manner as in a traditional buck converter. The freewheeling rectifier, usually a Schottky device, is replaced by a power MOSFET and is driven in a complementary or synchronous fashion relative to the main switching device; when one MOSFET is on, the other is off.
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Hysteretic Control Operation 1.2 Hysteretic Control Operation Hysteretic control, also called bang-bang control or ripple regulator control, maintains the output voltage within the hysteresis band centered about the internal reference voltage. Figure 1–2 shows a simplified example of a hysteretic controlled output voltage using the TPS5625 with a reference voltage of 2.500 V and a hysteresis band of 50 mV. If the output voltage is at or below the level of the reference minus one-half of the hyst
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Design Strategy 1.3 Design Strategy The SLVP111–114 evaluation modules (EVMs) are optimized for 5-V main input voltage and 6-A output current. The EVMs need an additional low current 12-V (30 mA max) input voltage for the controller. TI’s application report, Providing a DSP Power Solution from 5 V or 3.3 V Only Systems, TI literature number SPRA525 describes how one can implement a simple boost circuit for 5-V only input voltage applications. These EVMs are pin to pin compatible with SLVP104/105
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Design Specification Summary 1.4 Design Specification Summary This section summarizes the design requirements of the EVM converters. Although every attempt was made to accurately describe the performance of the EVM converters and the TPS56xx controllers, in case of conflicts, the TPS56xx data sheet takes precedence over this document. The TPS56xx family of controllers provides the necessary regulation functions. In addition to a reference voltage accuracy of ±1% over the full operating temperatu
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Design Specification Summary Table 1–2.EVM Converter Operating Specifications (Continued) Specification Min Typ Max Units || Output ripple SLVP111 (3.3 V) 66 mV p–p SLVP112 (2.5 V) 50 mV p–p SLVP113 (1.8 V) 36 mV p–p SLVP114 (1.5 V) 30 mV p–p Efficiency, 6 A load SLVP111 (3.3 V) 90% SLVP112 (2.5 V) 86.4% SLVP113 (1.8 V) 83.2% SLVP114 (1.5 V) 79.8% Efficiency, 4 A load SLVP111 (3.3 V) 91.6% SLVP112 (2.5 V) 88.6% SLVP113 (1.8 V) 85.1% SLVP114 (1.5 V) 81.9% † Vi = 5 V, Io = 6 A ‡ Io = 6 A, Vi = 5 V
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Schematic 1.5 Schematic Figure 1–3 shows the EVM converter schematic diagram. The schematic diagrams for the other EVM converters are identical except for the controller IC used. Figure 1–3. SLVP111–114 EVM Converter Schematic Diagram Introduction 1-7 J1–5 L1 V I J1–6 C2 150 μ F 6.3 V 2.2 μ H C1 + R1 R2 C3 150 μ F J1–9 C5 0.1 μ F 33 μ F 1 kΩ 10 kΩ 6.3 V RETURN 10 V J1–10 C4 150 μ F 6.3 V Q1 J1–7 Si4410 12 V C7 R15 J1–8 RETURN 1 M R3 J1–3 1 μ F PG J1–1 INHIBIT 10 Ω J1–15 SLVP111 = 3.3 V C9 J1–16
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Bill of Materials 1.6 Bill of Materials Table 1–3 lists materials required for the SLVP111–114 EVMs. Table 1–3.SLVP111–114 EVMs Bill of Materials Ref Des Part Number Description MFG C1 10TPA33M Capacitor, POSCAP, 33 μF, 10 V, 20% Sanyo C2 6TPB150M Capacitor, POSCAP, 150 μF, 6.3 V, 20% Sanyo C3 6TPB150M Capacitor, POSCAP, 150 μF, 6.3 V, 20% Sanyo C4 6TPB150M Capacitor, POSCAP, 150 μF, 6.3 V, 20% Sanyo C5 GRM39X7R104K016A Capacitor, Ceramic, 0.1 μF, 16 V, 10%, X7R muRata C6 GRM39X7R104K016A Capaci
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Bill of Materials Table 1–3.SLVP111–114 EVMs Bill of Materials (Continued) Ref Des Part Number Description MFG R7 Std Resistor, Chip, 1 kΩ, 1/16W, 5% R8 Std Resistor, Chip, 100 Ω, 1/16W, 1% R9 Std Resistor, Chip, 11 kΩ, 1/16W, 5% R10 Std Resistor, Chip, 100 Ω, 1/16W, 1% R11 Std Resistor, Chip, 20 kΩ, 1/16W, 1% R12 Std Resistor, Chip, 4.7 Ω, 1/16W, 5% R13 Std Resistor, Chip, 750 Ω, 1/16W, 5% R14 Std Resistor, Chip, 20 kΩ, 1/16W, 1% R15 Std Resistor, Chip, 1 MΩ, 1/16W, 5% U1a TPS5633PWP IC, PWM R
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Board Layout 1.7 Board Layout Figures 1–4 through 1–7 show the board layouts for the SLVP111–114 evaluation modules. Figure 1–4. Top Assembly Top Assembly Figure 1–5. Bottom Assembly (Top View) Bottom Assembly (Top View) Figure 1–6. Top Layer Top Layer 1-10
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Board Layout Figure 1–7. Bottom Layer (Top VIew) Bottom Layer (Top View) Introduction 1-11
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