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User's Guide
SNVA160A–May 2006–Revised April 2013
AN-1471 LM3489 Demonstration Board
1 Introduction
The LM3489 is a high efficiency PFET switching regulator controller that can be used to quickly and easily
develop a small, cost effective, switching buck regulator for a wide range of applications. The hysteretic
control architecture provides for simple design without any control loop stability concerns using a wide
variety of external components. The PFET architecture also allows for low component count as well as
ultra-low dropout, and 100% duty cycle operation. Another benefit is high efficiency operation at light loads
without an increase in output ripple. A dedicated Enable Pin (enabled if left unconnected) provides a
shutdown mode drawing only 7 µA.
The current limit protection can be implemented by measuring the voltage across the PFET’s R
DS(ON)
, thus,
eliminating the need for a sense resistor. The cycle-by-cycle current limit can be adjusted with a single
resistor, ensuring safe operation over a range of output currents.
This LM3489 demonstration board provides a 3.3 V output with 500 mA nominal load capability (maximum
1A) from a wide input voltage range of 7 V to 28 V. The reference design is optimized for overall
conversion efficiency. This document contains the demo board schematic, PCB layout, Bill of Materials
(BOM) and typical operating waveforms are provided for reference.
2 Evaluation Board Schematic
Figure 1. LM3489 Evaluation Board Schematic
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1
SNVA160A–May 2006–Revised April 2013 AN-1471 LM3489 Demonstration Board
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Verzeichnis
- ・ Blockdiagramm on Seite 1
- ・ Anwendungsbereich on Seite 8
