LM20146MHEVAL National Semiconductor, LM20146MHEVAL Datasheet

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LM20146MHEVAL

Manufacturer Part Number
LM20146MHEVAL
Description
BOARD EVALUATION FOR LM20146MH
Manufacturer
National Semiconductor
Series
PowerWise®r
Datasheets

Specifications of LM20146MHEVAL

Design Resources
LM20146 Design Spreadsheet
Main Purpose
DC/DC, Step Down
Outputs And Type
1, Non-Isolated
Voltage - Output
1.2V
Current - Output
6A
Voltage - Input
2.95 ~ 5.5V
Regulator Topology
Buck
Board Type
Fully Populated
Utilized Ic / Part
LM20146
Lead Free Status / RoHS Status
Contains lead / RoHS non-compliant
Power - Output
-
Frequency - Switching
-
© 2009 National Semiconductor Corporation
LM20146 Evaluation Board
Introduction
The LM20146 is a full-featured synchronous buck switching
regulator capable of driving up to 6A of load current. The abil-
ity to adjust the operating frequency from 250kHz to 750kHz
gives the designer flexibility in component selection. The
LM20146 is capable of converting an input voltage between
2.95V and 5.5V down to an output voltage as low as 0.8V.
Fault protection features include cycle-by-cycle current limit,
output power good, and output over-voltage protection. The
dual function soft-start/tracking pin can be used to control the
startup response of the LM20146, and the precision enable
pin can be used to easily sequence the LM20146 in sequence
critical applications. The LM20146 is available in an
eTSSOP-16 package with an exposed pad for enhanced ther-
mal performance.
300799
FIGURE 1. Evaluation Board Schematic
National Semiconductor
Application Note 1902
Daniel Tennant
January 16, 2009
The LM20146 evaluation board is designed to balance overall
solution size and transient response. The evaluation board
measures 1.5” x 1.5” on a four layer PCB with all components
placed on the top layer. The power stage and compensation
components are optimized for an input voltage of 5V, but for
testing purposes, the input can be varied across the entire
operating range. The output voltage of the evaluation board
is nominally 1.2V, but this voltage can be easily changed by
replacing one of the feedback resistors (R
control loop compensation of the LM20146 evaluation board
is designed to provide a stable solution over the entire input
voltage range with a fast transient response. The EN pin is
tied to V
through the enable test point
IN
with a 10kΩ resistor and can be toggled directly
FB1
www.national.com
or R
30079901
FB2
). The

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LM20146MHEVAL Summary of contents

Page 1

... LM20146 in sequence critical applications. The LM20146 is available in an eTSSOP-16 package with an exposed pad for enhanced ther- mal performance.     © 2009 National Semiconductor Corporation National Semiconductor Application Note 1902 Daniel Tennant January 16, 2009 The LM20146 evaluation board is designed to balance overall solution size and transient response. The evaluation board measures 1.5” ...

Page 2

... This point allows a scope probe to be connected to observe the switch node voltage. This terminal provides an oscilloscope probe connection directly to VOUT to probe the transient response and output voltage ripple. 2 Qty Manufacturer 1 National Semiconductor 1 TDK 1 TDK 0 N/A 1 ...

Page 3

Performance Characteristics Efficiency vs Load Load Regulation (V IN 30079915 = 5V) 1. Load Transient Response 30079917 Startup Waveform 30079920 3 Line Regulation (I = 6A) LOAD 30079916 30079919 www.national.com ...

Page 4

Component Selection This section provides a walk-through of the design process for the LM20146 evaluation board. Unless otherwise indicat- ed all formulas assume units of Amps (A) for current, Farads (F) for capacitance, Henries (H) for inductance, and Volts (V) ...

Page 5

C the value for R as outlined in the next section Once the value selected, resistor zero in the control loop to cancel ...

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PCB Component Placement www.national.com 30079913 Top Layer 30079921 Mid Layer 1 6 ...

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Mid Layer 2 30079923 Bottom Layer 7 www.national.com ...

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