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User’s Guide

SLUU070 - March 2001

Using the TPS62102 Low-Power High-Efficiency Buck

Converter Evaluation Module

Kurt Hesse Power Supply Control Products

Contents

1 Features 2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

2 Description 2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3 Feedback Considerations 4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4 Operating Instructions 6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

5 Evaluation Module Layouts 7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6 Evaluation Module Components 8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

7 References 9. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Summary of content (9 pages)

PAGE 1
User’s Guide SLUU070 - March 2001 Using the TPS62102 Low-Power High-Efficiency Buck Converter Evaluation Module Kurt Hesse Power Supply Control Products Contents 1 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 2 Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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SLUU070 1 Features The TPS62102 Low-Power High-Efficiency Buck Converter includes: • 2.5-V to 9-V Input Range • 0.8-V to 8-V Output Range • Dual Auto Mode for High Efficiency at Light Loads • Externally Synchronizable • 0% to 100% Duty Cycle • BICMOS for Low Quiescient, Standby, and Shutdown Currents • 8-Pin SOIC (D) Package 2 Description The TPS62102EVM–01 evaluation module is supplied fully assembled and ready to test.
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SLUU070 This evaluation module allows user control over the SD/SYNC and MODE pins of the TPS62102. As supplied, the MODE (CB1) pin should be left floating. This allows the TPS62102 to automatically determine whether it operates in the continuous frequency mode or in a pulsed frequency modulation (PFM) mode of operation. See the TPS62102 data sheet for details[1]. Phase 100 Gain (dB) 100 Phase (degrees) The SD/SYNC pin is jumpered to ground by default. This allows the TPS62102 to free run.
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SLUU070 3 Feedback Considerations Figure 2 shows the gain and phase response for the internal error amplifier. In addition to the compensation configuration used, many other feedback configurations are provided for on the evaluation module by using the optional component footprints. Figure 3 shows the schematic of the evaluation module with these additional footprints. As is evident, most any common feedback implementation can be achieved by simply shorting across pads or inserting passive components.
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SLUU070 3.2 Open-Loop Small Signal AC Model The circuit of Figure 4 is used to define the feedback loop for this evaluation module. 3.2.1 Specific Open-Loop Signal AC Model Considerations M1 is the lumped gain corresponding to the input voltage and the PWM gain. Since the ramp height in the chip is about 1V the PWM gain is 100%/V or just 1 in the free running case. The 8x factor comes from the input voltage of 8 V. The PWM gain increases with synchronization.
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SLUU070 4 Operating Instructions 4.1 Connect a dc Power Supply to Terminal TB1 The power supply should be capable of supplying up to 10 V at 0.5 A. The power supply should be set to its minimum output voltage level and current limited to 0.5 A. 4.2 Connect the Load to TB2 This load should be capable of handling 0.5 A at 3.5 V. 4.3 Place a Jumper on CB2 • Placing the jumper from pin 1 to pin 2 pulls SD/SYNC high, resulting in converter shutdown.
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SLUU070 5 Evaluation Module Layouts Evaluation module layout examples of the TPS62102EVM–01 PCB are shown in Figure 6 through Figure 8. They are not to scale and appear here only as a reference. Figure 6. Top Layer (top view) Figure 7.
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SLUU070 Figure 8. Assembly Drawing (top assembly) 6 Evaluation Module Components Table 1. TPS62102EVM–01 Components Description Reference Qty Manufacturer Part Number C1 1 100 µF, ±20%, 25 V, electrolytic Panasonic–ECG ECE–V1EA101UP C2 1 1.0 µF, +80%/–20%, 25 V, ceramic, Y5V Panasonic–ECG ECJ–3YF1E105Z C3, C5, C7 0 For evaluation use only C4 1 1.0 nF, ±10%, X7R, 50 V, ceramic Phycomp USA, Inc.
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IMPORTANT NOTICE Texas 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 discontinue any product or service without notice. Customers should obtain the latest relevant information before placing orders and should verify that such information is current and complete.