Datasheet

SLUU189 − July 2004
4
TPS40009-Based 5-A Converter in Less Than One Square Inch
TPS40009-Based 5-A Converter in Less Than One Square
Inch
Mark Dennis Systems Pow
er
Contents
1 Introduction 4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2 Features 4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3 Schematic 5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4 Design Procedure 6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5 PowerPAD Packaging 10. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6 Test Results/Performance Data 11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7 PCB Layout 15. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
8 List of Material 16. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1 Introduction
The TPS40009 is a voltage-mode, synchronous buck PWM controller that uses TI’s proprietary Predictive Gate
Drive technology to wring maximum efficiency from step-down converters. This controller provides a
bootstrap charging circuit to allow the use of an N-channel MOSFET as the topside buck switch to reduce
conduction losses and increase silicon device utilization. Predictive Gate Drive technology controls the delay
from main switch turn-off to synchronous rectifier turn-on and also the delay from rectifier turn-off to main switch
turn-on. This allows minimization of the losses in the MOSFET body diodes by reducing conduction and reverse
recovery time. This user’s guide provides details on a 5-A buck converter that converts 3.3 V down to a 1.2-V
level using the TPS40009 controller, with less than one square inch board area.
A schematic for the board is shown in Figure 1. A list of material is provided in the final section.
2 Features
The specification for this board is as follows:
D V
IN
= 3.0 V to 3.6 V
D V
OUT
= 1.2 V ± 3%
D 0 A ≤ I
OUT
≤ 5 A
D Efficiency > 90% with a load of 2 A
D Output voltage ripple < 2% V
OUT
D Physical size < 1 square inch circuit area