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SLUU186 − March 2004
4
TPS40055-Based Design Converts 12-V Bus to 1.8 V at 15 A (HPA070)
TPS40055-Based Design Converts 12-V Bus to
1.8 V at 15 A (HPA070)
Mark Dennis System Pow
er
Contents
1 Introduction 4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2 Features 4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3 Schematic 5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4 Component Selection 6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5 Test Setup 10. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6 Test Results and Performance Data 11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7 EVM Assembly Drawing and PCB Layout 12. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
8 List of Materials 15. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
9 References 16. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1 Introduction
In many modern electronic applications there is a growing demand for circuits to convert a12-V bus to digital
voltages as low as, but not limited to 1.8 V. The current requirements can range from below 1 A to over 15 A.
For high-efficiency and small circuit size the TPS40055 wide-input synchronous buck controller can be used
to provide the necessary control and drive functions to implement these converters. The TPS40055EVM−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 TPS40055 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
controller also provides a regulated 10-V bias voltage which supplies onboard drivers for the N-channel switch
and synchronous rectifier MOSFETs, utilizing adaptive gate drive logic to prevent cross conduction of the power
MOSFETs.
[1]
2 Features
The specification of this design is as follows:
D 92% peak efficiency at 6 A
D 88% peak efficiency at 15 A
D 1.8V output at 15 A
D V
IN
range from 10 V
DC
to 14 V
DC
D Small circuit size 1.4” x 2.5” SMT design, components on single side
D Line/load regulation < 0.5%
D High-frequency 300-kHz operation
D Transient deviation 60 mV with 10-A load step