Texas Instruments TPS40130EVM-001 User manual

User's GuideSLUU208 – October 2004
12-V Input, 1.5-V Output, 40-A Two Phase SynchronousBuck Converter Using the TPS40130
The TPS40130EVM-001 evaluation module (EVM) is a high efficiency, two phasesynchronous buck converter providing a fixed 1.5-V output at up to 40 A from a 12-Vinput bus. The EVM is designed to start up from a single supply, so no additional biasvoltage is required for start-up. The module uses the TPS40130 high frequency twophase controller.
Contents1 Description ........................................................................................... 22 TPS40130EVM-001 Electrical Performance Specifications ................................... 33 Schematics .......................................................................................... 44 Test Setup ........................................................................................... 75 TPS40130EVM-001 Typical Performance Data and Characteristic Curves............... 106 EVM Assembly Drawings and Layout .......................................................... 127 List of Materials .................................................................................... 16
List of Figures
1 TPS40130EVM-001 Power Stage/Control Schematic ......................................... 42 TPS40130EVM-001 Support Circuitry Schematic .............................................. 53 TPS40130EVM-001 Recommended Test Setup ............................................... 94 TPS40130EVM-001 Efficiency, V
12V_IN
= 10 V to 14 V,V
1V5_OUT
= 1.5 V, I
1V5_OUT
= 4 A to 40 A ........................................................ 105 TPS40130EVM-001 Line Regulation, I
1V5_OUT
= 20 A ........................................ 106 TPS40130EVM-001 Load Regulation .......................................................... 117 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 ...................................... 118 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 ..................................... 129 TPS40130EVM-001 Component Placement (Top View) .................................... 1310 TPS40130EVM-001 Silkscreen (Top View) ................................................... 1311 TPS40130EVM-001 Top Copper (Top View) .................................................. 1412 TPS40130EVM-001 Layer 2 (X-Ray Top View)............................................... 1413 TPS40130EVM-001 Layer 3 (X-Ray Top View)............................................... 1514 TPS40130EVM-001 Bottom Copper (X-Ray Bottom View) ................................. 15
List of Tables
1 TPS40130EVM-001 Electrical and Performance Specifications ............................. 32 Adjusting V
1V5_OUT
With R14 ...................................................................... 63 Adjusting Overcurrent Protection with R19 ...................................................... 64 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

www.ti.com
1 Description
1.1 Applications
1.2 Features
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 advancedtechnologies to improve its performance. Lossless DCR current sensing eliminates the need for a currentsense 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, evenas the user adjusts the output voltage, or accidentally shorts the feedback pin to ground.
•Nonisolated High Current Point of Load and Low Voltage Bus Converters•Video Graphic Adaptors•Internet Servers•Networking Equipment•Telecommunications Equipment•DC Power Distributed Systems
•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)
12-V Input, 1.5-V Output, 40-A Two Phase Synchronous Buck Converter Using the TPS401302 SLUU208 – October 2004

www.ti.com
2 TPS40130EVM-001 Electrical Performance Specifications
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 VMax input current V
IN
= 10 V, I
OUT
= 40 A 6.9 ANo-load input current V
IN
= 14 V, I
OUT
= 0 A 180 mA
OUTPUT CHARACTERISTICS
Output voltage R14 = 8.66 k Ω1.45 1.50 1.55 VOutput voltage regulation Line regulation (10 V < V
IN
< 14 V, I
OUT
= 20 A) 1%Load regulation (0 A < I
OUT
< 40 A, V
IN
= 12 V) 1%Output voltage ripple V
IN
= 14 V, I
OUT
= 40 A 30 mV
pp
Output load current 0 40 AOutput overcurrent Limit source current to 8.5 A none —Limit load current to 40 AOutput current limit Limit source current to V
IN
= 12 V 80 ASwitching frequency 300 330 360 kHzPeak efficiency V
OUT
= 1.5 V, 20 A < I
OUT
< 30 A V
12V_IN
= 10 V 91%V
12V_IN
= 12 V 90%V
12V_IN
= 14 V 89%Full load efficiency V
OUT
= 1.5 V, I
OUT
= 40 A V
12V_IN
= 10 V 89%V
12V_IN
= 12 V 88%V
12V_IN
= 14 V 87%
12-V Input, 1.5-V Output, 40-A Two Phase Synchronous Buck Converter Using the TPS40130SLUU208 – October 2004 3

www.ti.com
3 Schematics
+ + ++ + +
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

www.ti.com
+
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

www.ti.com
3.1 Adjusting Output Voltage (R14)
VVOUT VVREF R14 R6
R14
(1)
3.2 Adjusting Overvoltage Protection (R1)
VOVP VOVSET R1 R4
R1
(2)
3.3 Adjusting Overcurrent Protection (I
lim
)
Schematics
The regulated output voltage can be adjusted within a limited range by changing the ground resistor in thefeedback resistor divider (R14). The output voltage is given by Equation 1 , where V
VREF
= 0.7 V and R6 =10.0 k Ω.
Table 2 contains common values for R14 to generate popular output voltages. The TPS40130EVM-001 isstable through these output voltages but the efficiency may suffer as the power stage is optimized for the1.5-V output.
Table 2. Adjusting V
1V5_OUT
With R14
V
OUT
R14
3.3 V 2.67 k Ω2.5 V 3.83 k Ω2.2 V 4.64 k Ω2.0 V 5.36 k Ω1.8 V 6.34 k Ω1.5 V 8.66 k Ω1.2 V 14.0 k Ω
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 outputvoltage from 1.2 V to 3.3 V, the OVP set point can be adjusted to be closer to the output voltage bychanging R1. The output overvoltage set point is given by Equation 2 , where V
OVSET
= 0.816 V and R4 =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 mustbe closely observed.
The TPS40130EVM-001 is preconfigured with the overcurrent protection (OVP) set very high to allow theconverter 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 R19according to Table 3 .
Table 3. Adjusting Overcurrent Protection with R19
I
OUT
MAX CURRENT LIMIT R18 R19
30 A 40 A 2.21 k Ω464 Ω40 A 50 A 2.21 k Ω590 Ω50 A 60 A 2.21 k Ω715 Ω60 A 70 A 2.21 k Ω845 Ω70 A 80 A 2.21 k Ω1 k Ω
12-V Input, 1.5-V Output, 40-A Two Phase Synchronous Buck Converter Using the TPS401306 SLUU208 – October 2004

www.ti.com
3.4 Using an External 5-V Supply (R32 and R33)
4 Test Setup
4.1 Equipment
Test Setup
For more details on setting V
Ilim
for specific overcurrent protection levels, see the overcurrent protectionequations in the Functional Descriptions section of the TPS40130 data sheet.
The TPS40130EVM-001 is designed to be run from a single 12-V supply by incorporating a TL751 5-VLDO, however an external supply can be used if a separate 5-V bus is available in the target system. Touse an external 5-V supply, connect it through 5V_IN (J7) and remove R32 and R33 to disconnect theLDO from the circuit. The TPS40130EVM-001 requires approximately 50 mA of current from the 5-Vsupply.
4.1.1 Voltage Source
V
12V_IN
: The input voltage source (V
12V_IN
) should be a 0-V to 15-V variable dc source capable of 8.5 Adc.Connect V
12V_IN
to J1 and J6 as shown in Figure 1 .
4.1.2 Meters
A1: 0 Adc to 10 Adc ammeterV1: V
12V_IN
, 0 V to 15 V voltmeterV2: V
1V5_OUT
VOUT, 0 V to 5 V voltmeter
4.1.3 Loads
LOAD1: The output load (LOAD1) should be an electronic constant current mode load capable of 0 Adc to40 Adc at 1.5 V.
4.1.4 Recommended Wire Gauge
V
12V_IN
to J1 and J6: The connection between the source voltage, V
12V_IN
and J1 and J6 of HPA087 cancarry as much as 7 Adc. The minimum recommended wire size is AWG #16 with the total length of wireless than 4 feet (2 feet input, 2 feet return).
J4 to LOAD1: The connection between J4 of HPA087 and LOAD1 can carry as much as 40 Adc. Theminimum recommended wire size is 4 x AWG #16, with the total length of wire less than 1 foot.
J2 and J5 to LOAD1: The connection between J2 and J5 of HPA087 and LOAD1 can carry as much as40 Adc. The minimum recommended wire size is 2 x AWG #16 (two wires per connector), with the totallength of wire less than 1 foot.
12-V Input, 1.5-V Output, 40-A Two Phase Synchronous Buck Converter Using the TPS40130SLUU208 – October 2004 7

www.ti.com
4.2 Equipment Setup
Test Setup
4.1.5 Other
FAN: The TPS40130EVM-001 includes components that can get hot to the touch. Because this EVM isnot enclosed to allow probing of circuit nodes, a small fan capable of 200 to 400 lfm is required to reducecomponent surface temperatures to prevent user injury. The EVM should not be left unattended whilepowered or probed while the fan is not running.
OSCILLOSCOPE: A 60-MHz or faster oscilloscope can be used to determine the ripple voltage on1V5_OUT. The oscilloscope should be set for 1 M Ωimpedance, ac coupling, 1 µs/division horizontalresolution, 20 mV/division vertical resolution for taking output ripple measurements.
Shown in Figure 3 is the basic test setup recommended to evaluate the TPS40130EVM-001. Note thatalthough the return for J1, J2, J5, and J6 are all the same, the connections should remain separate asshown in Figure 3 .
4.2.1 Procedure
1. Working at an ESD workstation, make sure that any wrist straps, bootstraps, or mats are connectedreferencing the user to earth ground before power is applied to the EVM. Electrostatic smock andsafety glasses should also be worn.2. Prior to connecting the dc input source, V
12V_IN
, it is advisable to limit the source current from V
12V_IN
to7.0 A maximum. Make sure V
12V_IN
is initially set to 0 V and connected as shown in Figure 3 .3. Connect the ammeter A1 (0-A to 7-A range) between V
12V_IN
and J1 and J2 as shown in Figure 3 .4. Connect voltmeter V1 to 12V_IN + and 12V_IN– as shown in Figure 3 .5. Connect LOAD1 to J2 as shown in Figure 1 . Set LOAD1 to constant current mode to sink 0 Adc beforeV
12V_IN
is applied.6. Connect voltmeter, V2 across 1V5_OUT + and 1V5_OUT - as shown in Figure 3 .7. Place fan as shown in Figure 3 and turn on, making sure air is flowing across the EVM.
12-V Input, 1.5-V Output, 40-A Two Phase Synchronous Buck Converter Using the TPS401308 SLUU208 – October 2004

www.ti.com
A1
−
−
+
+
−− −−−
+
++++
−+
−+
−
+
V2
1V5_OUT 1V5_OUT_RTN2
12V_IN1 12V_IN2
5V_IN
+
−
−
+
Ground Clip
Oscilloscope
J3 J4 J5
J6
J1
J7
1M, AC
10mV / div
20MHz
LOAD1
1.5V @ 40A
Scope
Probe
1V5_OUT_SNS
1V5_OUT_RTN1
J2
V1
TPS40130EVM−001
Two Phase 12V to 1.5V @ 40A
FAN
V12V_IN
4.3 Startup/Shutdown Procedure
Test Setup
4.2.2 Diagram
Figure 3. TPS40130EVM-001 Recommended Test Setup
1. Increase V
12V_IN
(V1) from 0 Vdc to 10 Vdc2. Vary LOAD1 from 0 Adc to 40 Adc3. Vary V
12V_IN
(V1) from 10 Vdc to 14 Vdc4. Decrease LOAD1 to 0 A5. Decrease V
12V_IN
to 0 V
12-V Input, 1.5-V Output, 40-A Two Phase Synchronous Buck Converter Using the TPS40130SLUU208 – October 2004 9

www.ti.com
4.4 Equipment Shutdown
5 TPS40130EVM-001 Typical Performance Data and Characteristic Curves
5.1 Efficiency
HPA087A Efficiency
80
82
84
86
88
90
92
4 14 24 34
Output Current
Efficiency
Vin 10v
Vin 12v
Vin 14v
5.2 Line Regulation
Line Regulation
@ 20A Load
1.505
1.507
1.509
1.511
1.513
1.515
10 11 12 13 14
Input Voltage
Output Voltage
Line reg
TPS40130EVM-001 Typical Performance Data and Characteristic Curves
1. Shut down oscilloscope2. Shut down LOAD13. Shut down V
12V_IN4. Shut down fan
Figure 4 ,Figure 5 ,Figure 6 , and Figure 7 present typical performance curves for the TPS40130EVM-001.Since actual performance data can be affected by measurement techniques and environment variables,these curves are presented for reference and may differ from actual field measurements.
Figure 4. TPS40130EVM-001 Efficiency, V
12V_IN
= 10 V to 14 V,V
1V5_OUT
= 1.5 V, I
1V5_OUT
= 4 A to 40 A
Figure 5. TPS40130EVM-001 Line Regulation, I
1V5_OUT
= 20 A
12-V Input, 1.5-V Output, 40-A Two Phase Synchronous Buck Converter Using the TPS4013010 SLUU208 – October 2004