Texas Instruments TPS40051 User Manual Download Page 2

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EVM IMPORTANT NOTICE

Texas Instruments (TI) provides the enclosed product(s) under the following conditions:

This evaluation kit being sold by TI is intended for use for ENGINEERING DEVELOPMENT OR EVALUATION
PURPOSES ONLY
 and is not considered by TI to be fit for commercial use. As such, the goods being provided
may not be complete in terms of required design-, marketing-, and/or manufacturing-related protective
considerations, including product safety measures typically found in the end product incorporating the goods.
As a prototype, this product does not fall within the scope of the European Union directive on electromagnetic
compatibility and therefore may not meet the technical requirements of the directive.

Should this evaluation kit not meet the specifications indicated in the EVM User’s Guide, the kit may be returned
within 30 days from the date of delivery for a full refund. THE FOREGOING WARRANTY IS THE EXCLUSIVE
WARRANTY MADE BY SELLER TO BUYER AND IS IN LIEU OF ALL OTHER WARRANTIES, EXPRESSED,
IMPLIED, OR STATUTORY, INCLUDING ANY WARRANTY OF MERCHANTABILITY OR FITNESS FOR ANY
PARTICULAR PURPOSE.

The user assumes all responsibility and liability for proper and safe handling of the goods. Further, the user
indemnifies TI from all claims arising from the handling or use of the goods. Please be aware that the products
received may not be regulatory compliant or agency certified (FCC, UL, CE, etc.). Due to the open construction
of the product, it is the user’s responsibility to take any and all appropriate precautions with regard to electrostatic
discharge.

EXCEPT TO THE EXTENT OF THE INDEMNITY SET FORTH ABOVE, NEITHER PARTY SHALL BE LIABLE
TO THE OTHER FOR ANY INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES.

TI currently deals with a variety of customers for products, and therefore our arrangement with the user is not
exclusive
.

TI assumes no liability for applications assistance, customer product design, software performance, or
infringement of patents or services described herein
.

Please read the EVM User’s Guide and, specifically, the EVM Warnings and Restrictions notice in the EVM
User’s Guide prior to handling the product. This notice contains important safety information about temperatures
and voltages. For further safety concerns, please contact the TI application engineer.

Persons handling the product must have electronics training and observe good laboratory practice standards.

No license is granted under any patent right or other intellectual property right of TI covering or relating to any
machine, process, or combination in which such TI products or services might be or are used.

Mailing Address:

Texas Instruments
Post Office Box 655303
Dallas, Texas 75265

Copyright 

 2003, Texas Instruments Incorporated

Summary of Contents for TPS40051

Page 1: ...User s Guide 1 TPS40051 Based Design Converts 12 V Bus to 1 8 V at 15 A SLUP195 User s Guide ...

Page 2: ...e handling or use of the goods Please be aware that the products received may not be regulatory compliant or agency certified FCC UL CE etc Due to the open construction of the product it is the user s responsibility to take any and all appropriate precautions with regard to electrostatic discharge EXCEPT TO THE EXTENT OF THE INDEMNITY SET FORTH ABOVE NEITHER PARTY SHALL BE LIABLE TO THE OTHER FOR ...

Page 3: ...ertainty as to the load specification please contact a TI field representative During normal operation some circuit components may have case temperatures greater than 50 C The EVM is designed to operate properly with certain components above 50 C as long as the input and output ranges are maintained These components include but are not limited to linear regulators switching transistors pass transi...

Page 4: ...ns to implement these converters The TPS40051EVM 001 operates at 300 kHz and delivers 1 8 V at 15 A with efficiency over 90 for much of the load range and a full load efficiency of 88 The TPS40051 synchronous buck controller offers a variety of user programmable functions such as operating frequency soft start time voltage feed forward high side current limit and external loop compensation This co...

Page 5: ...SLUU161 April 2003 5 TPS40051 Based Design Converts 12 V Bus to 1 8 V at 15 A SLUP195 3 Schematic Figure 1 TPS40051EVM 001 SLUP195 Schematic ...

Page 6: ...portional to switching frequency drive voltage and the gate charge needed to enhance the N channel MOSFETs Effective heat removal allows the use of ultra small packaging while maintaining high component reliability The technical brief PowerPAD Thermally Enhanced Package 2 contains more information on the PowerPAD package 4 2 Frequency of Operation The clock oscillator frequency for the TPS40051 is...

Page 7: ...se VPD 8V and R4 is found to be 247 kΩ and a standard value of 243kΩ is selected Testing shows the startup voltage to be 9 2 V and the shutdown voltage to be 8 5 V 4 4 Inductance Value The output inductor L1 value used in the circuit of Figure 2 was selected from equation 4 L VOUT f IRIPPLE 1 VOUT VIN min in which IRIPPLE is usually chosen to be in the range between 10 and 40 of IOUT With IRIPPLE ...

Page 8: ... load current Vf allowed transient voltage rise Vi initial voltage For compactness while maintaining transient response capability two 470 µF POSCAP capacitors C16 C17 are fitted in parallel The total ESR of these capacitors is approximately 5 mΩ An additional 47 µF 6 3 V ceramic capacitor C15 is placed in parallel with the POSCAPs to help suppress high frequency noise generated by the fast curren...

Page 9: ... capacitor C7 placed in parallel with R9 to filter the signal 4 9 Snubber Component Selection Initially the junction of Q1 Q2 and L1 was ringing at a frequency near 100 MHz with a peak voltage near 30 V This was due to the extremely fast switching speed of the MOSFETs and the lack of any cross conduction C13 was added to shunt the high frequency ringing to ground and the peak voltage is now below ...

Page 10: ... a wire of 16AWG or larger diameter wire Monitor the output voltage on the PCB by connecting a voltmeter to TP9 and TP10 to prevent voltage drops through PCB traces and the output terminal block which can lead to substantial measurement errors 5 3 Oscilloscope Probe Test Jacks An oscilloscope probe test jack TP8 has been included to allow monitoring the ourput voltage ripple 5 4 Fan There is no co...

Page 11: ...ad ranges from 3 A to 12 A Figure 3 0 88 78 2 86 80 90 94 4 6 8 10 12 14 16 82 84 92 IOUT Output Current A Efficiency EFFICIENCY vs LOAD Figure 4 0 0 2 4 1 2 3 4 6 8 10 12 14 16 5 6 7 IOUT Output Current A P DISS Power Dissipation W POWER DISSIPATION vs LOAD 6 2 Closed Loop Performance 100 100 k 10 k 1 k 20 30 10 20 30 50 10 0 40 100 0 80 20 120 160 40 60 140 fOSC Oscillator Frequency kHz Gain dB ...

Page 12: ... IOUT 15 A to be less than 20 mVpp The transient response is shown in Figure 7 as the load is stepped from 5 A to 15 A The voltage deviation is less than 60 mV Figure 6 t Time 1 µs div IOUT 15 A VRIPPLE 10 mV div OUTPUT VOLTAGE RIPPLE Figure 7 t Time 200 µs div VOUT 50 mV div IOUT 5 A div TRANSIENT RESPONSE 7 EVM Assembly Drawing and PCB Layout Figure 8 Top Side Component Assembly ...

Page 13: ...SLUU161 April 2003 13 TPS40051 Based Design Converts 12 V Bus to 1 8 V at 15 A SLUP195 Figure 9 Top Side Copper Figure 10 Internal Layer 1 Copper ...

Page 14: ...SLUU161 April 2003 14 TPS40051 Based Design Converts 12 V Bus to 1 8 V at 15 A SLUP195 Figure 11 Internal Layer 2 Copper Figure 12 Bottom Layer Copper ...

Page 15: ...tching 10 mA 85 V 350 mW SOT23 Vishay Liteon BAS16 D2 1 Diode schottky 3 A 40 V SMC IR 30BQ040 J1 J2 2 Terminal block 4 pin 15 A 5 1 mm 0 80 x 0 35 OST ED2227 L1 1 1 Inductor SMT 1 7 µH 22 3 A 1 8 mΩ 0 512 x 0 512 Coiltronics HC1 1R7 Q1 1 1 MOSFET N channel VDS 30 V RDS 6 mΩ ID 30 A LFPAK Hitachi HAT2168H Q2 1 1 MOSFET N channel VDS 30 V RDS 4 2 mΩ ID 40 A LFPAK Hitachi HAT2167H R1 1 Resistor chip...

Page 16: ...ts 12 V Bus to 1 8 V at 15 A SLUP195 9 References 1 Data Sheet TPS40051 Wide Input Synchronous Buck Controller Texas Instruments Literature Number SLUS540 2 Technical Brief PowerPAD Thermally Enhanced Package Texas Instruments Literature Number SLMA002 ...

Page 17: ...nt that any license either express or implied is granted under any TI patent right copyright mask work right or other TI intellectual property right relating to any combination machine or process in which TI products or services are used Information published by TI regarding third party products or services does not constitute a license from TI to use such products or services or a warranty or end...

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