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User's Guide

SLUU395–December 2009

Using the TPS40192EVM-525, A 12-V Input, 1.8-V Output,

10-A Synchronous Buck Converter

Contents

1 Introduction .................................................................................................................. 2

2 TPS40192EVM-525 Electrical Performance Specifications ........................................................... 3

3 Schematic .................................................................................................................... 4

4 Test Setup ................................................................................................................... 7

5 TPS40192EVM Typical Performance Data and Characteristic Curves ............................................ 11

6 EVM Assembly Drawings and Layout .................................................................................. 13

7 List of Materials ............................................................................................................ 17

List of Figures

1 TPS40198EVM-525 Schematic ........................................................................................... 4

2 TPS40192EVM-525 Recommended Test Setup ....................................................................... 9

3 Output Ripple Measurement – Tip and Barrel Using TP15 and TP16 ............................................. 10

4 Control Loop Measurement Setup ...................................................................................... 10

5 TPS40192EVM-525 Efficiency vs Load Current,Vin = 8 V - 14 V, Vout = 1.8 V, Iout = 0 A - 10 A ............ 11

6 TPS40192EVM-525 Output Voltage vs Load Current,Vin = 8 V - 14 V, Vout = 1.8 V, Iout = 0 A - 10 A...... 12

7 TPS40192EVM-525 Output Voltage Ripple,Vin = 14 V, Vout = 1.8 V, Iout = 10 A............................... 12

8 TPS40192EVM-525 Switching Waveforms,CH1: SW(TP9), CH2: HDRV(TP8), CH3: LDRV(TP10); Vin =

14 V, Vout = 1.8 V, Iout = 10 A.......................................................................................... 13

9 TPS40192EVM-525 Component Placement (Viewed From Top)................................................... 14

10 TPS40192EVM-525 Silkscreen (Viewed From Top).................................................................. 14

11 TPS40192EVM-525 Top Copper (Viewed From Top)................................................................ 15

12 TPS40192EVM-525 Bottom Copper (X-Ray View From Top)....................................................... 15

13 TPS40192EVM-525 Internal 1 (X-Ray View From Top).............................................................. 16

14 TPS40192EVM-525 Internal 2 (X-Ray View From Top).............................................................. 16

List of Tables

1 Adjusting V

OUT

with R7...................................................................................................... 5

2 Adjusting V

SCP

With R9 ..................................................................................................... 5

3 TPS40192EVM-525 Bill of Materials.................................................................................... 17

SLUU395–December 2009 Using the TPS40192EVM-525, A 12-V Input, 1.8-V Output, 10-A Synchronous

Buck Converter

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Summary of content (19 pages)

PAGE 1
User's Guide SLUU395 – December 2009 Using the TPS40192EVM-525, A 12-V Input, 1.8-V Output, 10-A Synchronous Buck Converter 1 2 3 4 5 6 7 Contents Introduction .................................................................................................................. 2 TPS40192EVM-525 Electrical Performance Specifications ........................................................... 3 Schematic ..........................................................................................................
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Introduction 1 www.ti.com Introduction The TPS40192EVM-525 evaluation module (EVM) is a synchronous buck converter providing a fixed 1.8-V output at up to 10 A from a 12-V input bus. The EVM is designed to start up from a single supply; so, no additional bias voltage is required for start-up. The module uses the TPS40192 reduced pin count, mid-voltage, synchronous buck controller and TI's NexFET high performance MOSFETs. 1.
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TPS40192EVM-525 Electrical Performance Specifications www.ti.com 2 TPS40192EVM-525 Electrical Performance Specifications Parameter Notes and Conditions Min Nom Max Units Input Characteristics VIN Input voltage 12 14 IIN Input current VIN = Min, IOUT = Max 8 2.7 2.85 No load input current VIN = Min, IOUT = 0A 48 60 mA VIN_UVLO Input UVLO IOUT = Min to Max 4.2 4.4 V VIN_OV Input OV IOUT = Min to Max 3.
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Schematic 3 www.ti.com Schematic NOTE: For reference only; see Table 4: Bill of Materials for specific values Figure 1. TPS40198EVM-525 Schematic 4 Using the TPS40192EVM-525, A 12-V Input, 1.
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Schematic www.ti.com 3.1 Adjusting Output Voltage (R5) The regulated output voltage can be adjusted within a limited range by changing the ground resistor in the feedback resistor divider (R7). The output voltage is given by the formula V VOUT + VVREF R8 ) R7 R7 (1) Where VVREF = 0.591 V and R8 = 20 kΩ Table 1 contains common values for R7 to generate popular output voltages. TPS40192EVM-525 is stable through these output voltages but the efficiency may suffer as the power stage is optimized for the 1.
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Schematic 3.3.1 www.ti.com Test Point Label Use Section TP7 GND Ground for SW, LDRV, and HDRV measurements 3.3.4 TP8 HDRV Monitor high-side gate drive (Q2) 3.3.4 TP9 SW Monitor switch-node waveforms 3.3.4 TP10 LDRV Monitor low-side gate drive (Q3) 3.3.4 TP11 GND Ground for loop-monitoring probe 3.3.5 TP12 CH1 Loop injection point and injection monitoring point 3.3.5 TP13 CH2 Loop injection point and output response monitoring point 3.3.
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Test Setup www.ti.com By moving channel A from TP12 to TP6 (COMP), the control-to-output response of the power stage (also referred to as the power-stage transfer function) can be directly measured. See Section 3.9 for a detailed procedure of loop-response measurements. 3.3.6 Output Voltage Monitoring (TP15 and TP16) TPS40192EVM-525 provides two test points for measuring the voltage generated by the module.
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Test Setup 4.1.4 www.ti.com Oscilloscope A digital or analog oscilloscope can be used to measure the ripple voltage on VOUT. The oscilloscope should be set for 1-MΩ impedance, 20-MHz bandwidth, AC coupling, 1-μs/division horizontal resolution, 10-mV/division vertical resolution for taking output ripple measurements. TP15 and TP16 can be used to measure the output ripple voltage by placing the oscilloscope probe tip through TP15 and holding the ground barrel to TP16 as shown in Figure 3.
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Test Setup www.ti.com 4.2.2 Diagrams FAN Oscilloscope 1MW, AC 20mV / div 20MHz Short See Tip and Barrel Measurement for Vout ripple + + LOAD1 1.8V @ 10A V2 + - - VVIN + V1 A1 TEXAS INSTRUMENTS TPS40192EVM-525 FEATURING Figure 2. TPS40192EVM-525 Recommended Test Setup Metal Ground Barrel Probe Tip TP15 TP16 Tip and Barrel Vout ripple measurement Figure 3.
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Test Setup www.ti.com Network Analyzer FAN Short - + Isolation Transformer + LOAD1 1.8V @ 10A V2 + - - VVIN + V1 A1 TEXAS INSTRUMENTS TPS40192EVM-525 FEATURING Figure 4. Control Loop Measurement Setup 4.3 Start-Up/Shutdown Procedure 1. 2. 3. 4. 5. 4.4 Output Ripple Voltage Measurement Procedure 1. 2. 3. 4. 5. 6. 7. 10 Increase VIN from 0 V to 12 Vdc. Vary LOAD1 from 0 to10 Adc. Vary VIN from 8 Vdc to 14 Vdc. Decrease LOAD1 to 0 A. Decrease VIN to 0 Vdc.
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TPS40192EVM Typical Performance Data and Characteristic Curves www.ti.com 4.5 Control Loop Gain and Phase Measurement Procedure 1. 2. 3. 4. 5. 6. Connect a 1-kHz to 1-MHz isolation transformer to TP12 and TP13 as shown in Figure 4. Connect the input signal amplitude measurement probe (channel A) to TP12 as shown in Figure 4. Connect the output signal amplitude measurement probe (channel B) to TP13 as shown in Figure 4.
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TPS40192EVM Typical Performance Data and Characteristic Curves 5.2 www.ti.com Line and Load Regulation VO - Output Voltage - V 1.813 VI = 14 V 1.812 VI = 12 V 1.811 VI = 8 V 1.810 0 2 4 6 8 IO - Load Current - A 10 12 Figure 6. TPS40192EVM-525 Output Voltage vs Load Current, Vin = 8 V - 14 V, Vout = 1.8 V, Iout = 0 A - 10 A 5.3 Output Voltage Ripple Figure 7. TPS40192EVM-525 Output Voltage Ripple, Vin = 14 V, Vout = 1.8 V, Iout = 10 A 12 Using the TPS40192EVM-525, A 12-V Input, 1.
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EVM Assembly Drawings and Layout www.ti.com 5.4 Switch Node Figure 8. TPS40192EVM-525 Switching Waveforms, CH1: SW(TP9), CH2: HDRV(TP8), CH3: LDRV(TP10); Vin = 14 V, Vout = 1.8 V, Iout = 10 A 6 EVM Assembly Drawings and Layout The following figures (Figure 9 through Figure 14) show the design of the TPS40192EVM-525 printed-circuit board. The EVM has been designed using a 4-layer, 2-oz copper-clad circuit board 1.20-inch × 1.00-inch with all components in a 1.25-in. × 0.8-in.
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EVM Assembly Drawings and Layout www.ti.com TEXAS INSTRUMENTS TPS 40192 EVM -525 FEATURIN G Figure 10. TPS40192EVM-525 Silkscreen (Viewed From Top) Figure 11. TPS40192EVM-525 Top Copper (Viewed From Top) 14 Using the TPS40192EVM-525, A 12-V Input, 1.
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EVM Assembly Drawings and Layout www.ti.com Figure 12. TPS40192EVM-525 Bottom Copper (X-Ray View From Top) Figure 13. TPS40192EVM-525 Internal 1 (X-Ray View From Top) SLUU395 – December 2009 Submit Documentation Feedback Using the TPS40192EVM-525, A 12-V Input, 1.
PAGE 16
EVM Assembly Drawings and Layout www.ti.com Figure 14. TPS40192EVM-525 Internal 2 (X-Ray View From Top) 16 Using the TPS40192EVM-525, A 12-V Input, 1.
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List of Materials www.ti.com 7 List of Materials Figure 14 lists the EVM components as configured according to the schematic shown in Section 3. Table 3. TPS40192EVM-525 Bill of Materials QTY RefDes Value Description Size Part Number MFR 1 C1 100pF Capacitor, Ceramic, 10V, C0G, 10% 0603 STD STD 1 C2 1000pF Capacitor, Ceramic, 10V, C0G, 10% 0603 STD STD 1 C3 10nF Capacitor, Ceramic, 10V, C0G, 10% 0603 STD STD 1 C4 1.
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EVALUATION BOARD/KIT IMPORTANT NOTICE Texas Instruments (TI) provides the enclosed product(s) under the following conditions: This evaluation board/kit is intended for use for ENGINEERING DEVELOPMENT, DEMONSTRATION, OR EVALUATION PURPOSES ONLY and is not considered by TI to be a finished end-product fit for general consumer use. Persons handling the product(s) must have electronics training and observe good engineering practice standards.
PAGE 19
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.