Texas Instruments TPS40130EVM-001 User Manual

12-V Input, 1.5-V Output, 40-A Two Phase Synchronous

Buck Converter Using the TPS40130

The TPS40130EVM-001 evaluation module (EVM) is a high efficiency, two phase
synchronous buck converter providing a fixed 1.5-V output at up to 40 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 TPS40130 high frequency two
phase controller.

Contents

1 Description ........................................................................................... 2

2 TPS40130EVM-001 Electrical Performance Specifications ................................... 3

3 Schematics .......................................................................................... 4

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

5 TPS40130EVM-001 Typical Performance Data and Characteristic Curves............... 10

6 EVM Assembly Drawings and Layout .......................................................... 12

7 List of Materials .................................................................................... 16

User's Guide

SLUU208 – October 2004

List of Figures

1 TPS40130EVM-001 Power Stage/Control Schematic ......................................... 4

2 TPS40130EVM-001 Support Circuitry Schematic .............................................. 5

3 TPS40130EVM-001 Recommended Test Setup ............................................... 9

4 TPS40130EVM-001 Efficiency, V

V

= 1.5 V, I

1V5_OUT

= 4 A to 40 A ........................................................ 10

1V5_OUT

5 TPS40130EVM-001 Line Regulation, I

12V_IN

= 10 V to 14 V,

= 20 A ........................................ 10

1V5_OUT

6 TPS40130EVM-001 Load Regulation .......................................................... 11

7 TPS40130EVM-001 5 A to 55 A Transient Response, 5 A to 55 A at 3 A/µs,

I

1V5_OUT (10A/div)

, V

1V5_OUT(rip)

(20 mv/div), Time 10 µs/div ...................................... 11

8 TPS40130EVM-001 55 A to 5 A Transient Response, 55 A to 5 A at 3 A/µs,

I

1V5_OUT (10A/div)

, V

1V5_OUT(rip)

(20 mV/div), Time 10 µs/div ..................................... 12

9 TPS40130EVM-001 Component Placement (Top View) .................................... 13

10 TPS40130EVM-001 Silkscreen (Top View) ................................................... 13

11 TPS40130EVM-001 Top Copper (Top View) .................................................. 14

12 TPS40130EVM-001 Layer 2 (X-Ray Top View)............................................... 14

13 TPS40130EVM-001 Layer 3 (X-Ray Top View)............................................... 15

14 TPS40130EVM-001 Bottom Copper (X-Ray Bottom View) ................................. 15

List of Tables

1 TPS40130EVM-001 Electrical and Performance Specifications ............................. 3

2 Adjusting V

With R14 ...................................................................... 6

1V5_OUT

3 Adjusting Overcurrent Protection with R19 ...................................................... 6

4 TPS40130EVM-001 Bill of Materials ........................................................... 16

12-V Input, 1.5-V Output, 40-A Two Phase Synchronous Buck Converter Using the TPS40130SLUU208 – October 2004 1

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Description

1 Description

The TPS40130EVM-001 is designed to use a regulated 12-V (10-V to 14-V) bus to produce a high current,
regulated 1.5-V output at up to 40 A of load current. The TPS40130EVM-001 uses a number of advanced
technologies to improve its performance. Lossless DCR current sensing eliminates the need for a current
sense resistor, reduces losses, and improves efficiency. A unity gain amplifier provides accurate,
integrated remote sense capabilities for highly accurate, point of load regulated output voltages.
Independent, programmable overvoltage protection (OVP) provides accurate overvoltage protection, even
as the user adjusts the output voltage, or accidentally shorts the feedback pin to ground.

1.1 Applications

• Nonisolated High Current Point of Load and Low Voltage Bus Converters

• Video Graphic Adaptors

• Internet Servers

• Networking Equipment

• Telecommunications Equipment

• DC Power Distributed Systems

1.2 Features

• 91% Peak and 89% Full Load Efficiency at 10-V Input

• 10-V to 14-V Input Range

• 1.5-V Fixed Output, Adjustable with Single Resistor

• 40-Adc Steady State Output Current

• 330-kHz per Phase Operation (660-kHz Output Ripple)

• Single Main Switch MOSFET and Dual Synchronous Rectifier MOSFET for Each Phase

• Single Component Side, Surface Mount Design (4.5" × 4.0”)

• Current Mode Control with Forced Current Sharing

• Four Layer PCB with all Components on Top Side

• Convenient Test Points for Probing Critical Waveforms and Noninvasive Loop Response Testing

• 5-V LDO for Single Supply Operation

• Space for the TPS40120 Digitally Controlled Resistor Network for 6-Bit VID Control (Not Populated)

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2 TPS40130EVM-001 Electrical Performance Specifications

Table 1. TPS40130EVM-001 Electrical and Performance Specifications

PARAMETER TEST CONDITIONS MIN TYP MAX UNIT

INPUT CHARACTERISTICS

Input voltage range 10 14 V
Max input current VIN= 10 V, I
No-load input current VIN= 14 V, I

OUTPUT CHARACTERISTICS

Output voltage R14 = 8.66 k Ω 1.45 1.50 1.55 V
Output voltage regulation Line regulation (10 V < VIN< 14 V, I

Load regulation (0 A < I
Output voltage ripple VIN= 14 V, I
Output load current 0 40 A
Output overcurrent Limit source current to 8.5 A none —

Limit load current to 40 A
Output current limit Limit source current to VIN= 12 V 80 A
Switching frequency 300 330 360 kHz
Peak efficiency V

Full load efficiency V

= 1.5 V, 20 A < I

OUT

= 1.5 V, I

OUT

TPS40130EVM-001 Electrical Performance Specifications

= 40 A 6.9 A

OUT

= 0 A 180 mA

OUT

= 20 A) 1%

OUT

< 40 A, VIN= 12 V) 1%

OUT

= 40 A 30 mV

OUT

< 30 A V

OUT

= 40 A V

OUT

= 10 V 91%

12V_IN

V

= 12 V 90%

12V_IN

V

= 14 V 89%

12V_IN

= 10 V 89%

12V_IN

V

= 12 V 88%

12V_IN

V

= 14 V 87%

12V_IN

pp

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+ + ++ + +

Schematics

3 Schematics

Figure 1. TPS40130EVM-001 Power Stage/Control Schematic

12-V Input, 1.5-V Output, 40-A Two Phase Synchronous Buck Converter Using the TPS401304 SLUU208 – October 2004

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+

Schematics

Figure 2. TPS40130EVM-001 Support Circuitry Schematic

12-V Input, 1.5-V Output, 40-A Two Phase Synchronous Buck Converter Using the TPS40130SLUU208 – October 2004 5

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V

VOUT

 V

VREF



R14 R6

R14

V

OVP

 V

OVSET



R1 R4

R1

Schematics

3.1 Adjusting Output Voltage (R14)

The regulated output voltage can be adjusted within a limited range by changing the ground resistor in the
feedback resistor divider (R14). The output voltage is given by Equation 1 , where V

10.0 k Ω .

Table 2 contains common values for R14 to generate popular output voltages. The TPS40130EVM-001 is

stable through these output voltages but the efficiency may suffer as the power stage is optimized for the

1.5-V output.

= 0.7 V and R6 =

VREF

(1)

3.2 Adjusting Overvoltage Protection (R1)

The output voltage is protected through an overvoltage protection circuit separate from the feedback loop,
to prevent damaging the 4-V output capacitors. Initially set for 3.5 V to allow the user to adjust the output
voltage from 1.2 V to 3.3 V, the OVP set point can be adjusted to be closer to the output voltage by
changing R1. The output overvoltage set point is given by Equation 2 , where V

10.0 k Ω .

Setting R1 = R14 provides 14% to 18% margin between the voltage set value and the OVP set point.
Narrower overvoltage margins can be obtained, however the tolerance on the OVP reference voltage must
be closely observed.

Table 2. Adjusting V

V

OUT

3.3 V 2.67 k Ω

2.5 V 3.83 k Ω

2.2 V 4.64 k Ω

2.0 V 5.36 k Ω

1.8 V 6.34 k Ω

1.5 V 8.66 k Ω

1.2 V 14.0 k Ω

1V5_OUT

With R14

R14

= 0.816 V and R4 =

OVSET

(2)

3.3 Adjusting Overcurrent Protection (I

The TPS40130EVM-001 is preconfigured with the overcurrent protection (OVP) set very high to allow the
converter to deliver high-current, short duration loads, operate under higher loads with sufficient air flow,
but still provide output short-circuit protection. To set the current limit to a lower value, change R19
according to Table 3 .

Table 3. Adjusting Overcurrent Protection with R19

I

MAX CURRENT LIMIT R18 R19

OUT

30 A 40 A 2.21 k Ω 464 Ω
40 A 50 A 2.21 k Ω 590 Ω
50 A 60 A 2.21 k Ω 715 Ω
60 A 70 A 2.21 k Ω 845 Ω
70 A 80 A 2.21 k Ω 1 k Ω

12-V Input, 1.5-V Output, 40-A Two Phase Synchronous Buck Converter Using the TPS401306 SLUU208 – October 2004

)

lim