herunterladen
User's Guide
SNVA389A–July 2009–Revised May 2013
AN-1951 LM3000 Evaluation Board
1 Introduction
The LM3000 evaluation board is designed to provide the design engineer with a fully-functional power
converter based solution using Dual Output Emulated Current Mode Controller in LM3000. This evaluation
board provides two output voltages of 3.3V and 1.2V. The 3.3V output is designed to handle a maximum
current of 8A; whereas the 1.2V output has a maximum current capability of 15A. The switching frequency
for the converter is set at 500 kHz. The gate signals for each output voltage will be 180 degree out of
phase from each other. The printed circuit board consists of 4 layers of FR4 material with 2 ounce copper
on top and bottom layer and 1 ounce copper for internal layers. This application note contains the
evaluation board schematic, bill of materials (BOM) and a quick setup procedure. Refer to the LM3000
Dual Synchronous Emulated Current-Mode Controller (SNVS612) data sheet for complete circuit design
information.
The performance of the evaluation board is as follows:
Input Range : 6V to 18V
Output Voltage 1 (VO1) : 3.3V
Output Current 1 : 0 to 8A
Output Voltage 2 (VO2) : 1.2V
Output Current 2 : 0 to 15A
Switching Frequency : 500 kHz
Load Regulation : 1%
Board Size : 2.68 x 3.146 x 0.068 inches
2 Powering and Loading Considerations
Read this entire page prior to attempting to power the evaluation board.
2.1 Quick Setup Procedure
1. Set the input power supply current limit to 10A. Turn off the input power supply. Connect the input
power supply to VIN terminal. Make sure to connect power supply ground to each GND1 and GND2
terminals in order to provide a short path for input current to return to the power supply.
2. Connect the load with an 8A capability on VO1 and 15A capability on VO2. Connect the positive
terminal to VO1 and VO2 and negative terminal to GND1 and GND2.
3. Connect a secondary power supply to EN1 and EN2 terminals. Set the power supply voltage to 5V.
The ground return for this power supply should be connected to GND terminal. Since the evaluation
board is configured such that V
OUT2
tracks V
OUT1
, therefore V
OUT2
cannot be turned on without turning on
V
OUT1
. Different configuration might be required in order to turn on VOUT2 independently. This will be
discussed later in the Tracking section of this application notes.
4. Set V
IN
to 12V with no load being applied. Turn on the input power supply followed by the secondary
power supply in order to power up the enable pins. The output voltage should be in regulation with a
value of 3.3V on VO1 and 1.2V on VO2.
5. Slowly increase the load in each output into its maximum output current while monitoring the output
voltages in each channel. The output voltages should also be in regulation at each respective
maximum output current.
1
SNVA389A–July 2009–Revised May 2013 AN-1951 LM3000 Evaluation Board
Submit Documentation Feedback
Copyright © 2009–2013, Texas Instruments Incorporated
Verzeichnis
- ・ Blockdiagramm on Seite 5
- ・ Anwendungsbereich on Seite 11
