Texas Instruments Boost Controller for LED Backlighting LM3430EVAL/NOPB LM3430EVAL/NOPB Datenbogen
Produktcode
LM3430EVAL/NOPB
Cox
Vo
GND
Oscilloscope
Vo
GND
GND
Vin
40V, 6A
Power Supply
+
-
V
LM3430
Evaluation Board
50W Electronic
Load
+
-
V
Ammeter
Ammeter
Voltmeter
Voltmeter
A
A
Powering the Converter
3
Powering the Converter
The example circuit for the LM3430 Evaluation Board is optimized to run at inputs of 12V or 24V, however
the circuit will operate with input voltages ranging from 6.0V to 40.0V connected between the ‘VIN’ and
‘GND’ terminals on the right side of the board. Fixed loads, resistors, and variable electronic loads can be
connected between the ‘Vo’ and ‘GND’ terminals on the left side of the board.
the circuit will operate with input voltages ranging from 6.0V to 40.0V connected between the ‘VIN’ and
‘GND’ terminals on the right side of the board. Fixed loads, resistors, and variable electronic loads can be
connected between the ‘Vo’ and ‘GND’ terminals on the left side of the board.
lists all the
components used in the example circuit.
4
Enabling the Converter
The OFF terminal controls the state of the converter while power is applied to the input terminals. The
LM340 is disabled whenever the voltage at OFF is a logic high. (Above 2.0V.) The LM3430 is enabled
whenever the OFF terminal is open-circuited or connected to ground. Upon enabling the LM3430 will
perform a soft-start, after which the output is ready to supply current to the load.
LM340 is disabled whenever the voltage at OFF is a logic high. (Above 2.0V.) The LM3430 is enabled
whenever the OFF terminal is open-circuited or connected to ground. Upon enabling the LM3430 will
perform a soft-start, after which the output is ready to supply current to the load.
5
Testing the Converter
shows a block diagram of connections for making measurements of efficiency. The wires used for
making connections at both the input and output should be rated to at least 10A of continuous current and
should be no longer than is needed for convenient testing. A series ammeter capable of measuring 10A or
more should be used for both the input and the output lines. Dedicated voltmeters should be connected
with their positive and negative leads right at the four power terminals at the sides of the evaluation board.
This measurement technique minimizes the resistive loss in the wires that connect the evaluation board to
the input power supply and the electronic load.
should be no longer than is needed for convenient testing. A series ammeter capable of measuring 10A or
more should be used for both the input and the output lines. Dedicated voltmeters should be connected
with their positive and negative leads right at the four power terminals at the sides of the evaluation board.
This measurement technique minimizes the resistive loss in the wires that connect the evaluation board to
the input power supply and the electronic load.
Output voltage ripple measurements should be taken directly across the 100 nF ceramic capacitor Cox,
placed right between the output terminals. Care must be taken to minimize the loop area between the
oscilloscope probe tip and the ground lead. One method to minimize this loop is to remove the probe’s
spring tip and ‘pigtail’ ground lead and then wind bare wire around the probe shaft. The bare wire should
contact the ground of the probe, and the end of the wire can then contact the ground side of Cox.
placed right between the output terminals. Care must be taken to minimize the loop area between the
oscilloscope probe tip and the ground lead. One method to minimize this loop is to remove the probe’s
spring tip and ‘pigtail’ ground lead and then wind bare wire around the probe shaft. The bare wire should
contact the ground of the probe, and the end of the wire can then contact the ground side of Cox.
shows a diagram of this method.
Figure 3. Efficiency Measurement Setup
Figure 4. Output Voltage Ripple Measurement Setup
2
AN-1529 LM3430 Evaluation Board
SNVA187C – January 2007 – Revised May 2013
Copyright © 2007–2013, Texas Instruments Incorporated