Texas Instruments Evaluation Board for the LM2854 LM2854EVAL LM2854EVAL Scheda Tecnica
Codici prodotto
LM2854EVAL
PVIN
AVIN
EN
AGND
PGND
FB
SW
LM2854
V
IN
V
OUT
SS
C
IN
L
O
C
O
R
FB1
R
COMP
C
COMP
R
FB2
C
SS
User's Guide
SNVA323B – March 2008 – Revised May 2013
AN-1786 LM2854 500 kHz Buck Regulator Evaluation
Board
1
Introduction
The LM2854 PowerWise
®
SIMPLE SWITCHER
®
buck regulator evaluation board is a 500 kHz step-down
voltage regulator capable of driving up 0A to 4A load current with excellent power conversion efficiency. A
typical schematic of an LM2854 application is given in Figure 1. The LM2854 pin-out and pin description
are given in
typical schematic of an LM2854 application is given in Figure 1. The LM2854 pin-out and pin description
are given in
and
, respectively.
The LM2854 evaluation board is designed to accept an input voltage rail between 2.95V and 5.5V and
deliver a fixed and highly accurate output voltage of 1.2V. The output voltage level can be changed by
modification of the one feedback resistor value. Externally established soft-start with a small value
capacitance facilitates a controlled, well-defined and monotonic start-up output voltage characteristic. In
addition, the LM2854 is capable of starting monotonically and glitch free into a pre-biased load.
deliver a fixed and highly accurate output voltage of 1.2V. The output voltage level can be changed by
modification of the one feedback resistor value. Externally established soft-start with a small value
capacitance facilitates a controlled, well-defined and monotonic start-up output voltage characteristic. In
addition, the LM2854 is capable of starting monotonically and glitch free into a pre-biased load.
With some of the required voltage loop compensation components integrated in the regulator, the number
of external passive components and PC board area typically necessary in a voltage mode buck converter
application are reduced. An LM2854 based regulator design with type III loop compensation can be
implemented with as few as eight external components. Only two small size external compensation
components are required, similar to that commonly involved with current mode control compensation.
Unlike a compensation solution where all the compensation components are integrated, the LM2854 has
the flexibility to deal with ceramic and/or electrolytic based load capacitance spanning a wide range of
capacitor values.
of external passive components and PC board area typically necessary in a voltage mode buck converter
application are reduced. An LM2854 based regulator design with type III loop compensation can be
implemented with as few as eight external components. Only two small size external compensation
components are required, similar to that commonly involved with current mode control compensation.
Unlike a compensation solution where all the compensation components are integrated, the LM2854 has
the flexibility to deal with ceramic and/or electrolytic based load capacitance spanning a wide range of
capacitor values.
Lossless cycle-by-cycle peak current limit is used to protect the load from an overcurrent or short-circuit
fault, and an enable comparator permits system sequencing or increase of the input UVLO above the
nominal 2.7V level. The device is available in a power enhanced HTSSOP-16 package featuring an
exposed die attach pad that improves the thermal performance of the regulator.
fault, and an enable comparator permits system sequencing or increase of the input UVLO above the
nominal 2.7V level. The device is available in a power enhanced HTSSOP-16 package featuring an
exposed die attach pad that improves the thermal performance of the regulator.
Figure 1. Typical System Application using LM2854 Synchronous Buck Regulator
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1
SNVA323B – March 2008 – Revised May 2013
AN-1786 LM2854 500 kHz Buck Regulator Evaluation Board
Copyright © 2008–2013, Texas Instruments Incorporated