Texas Instruments LM3404 Evaluation Boards LM3404HVEVAL/NOPB LM3404HVEVAL/NOPB Benutzerhandbuch
Produktcode
LM3404HVEVAL/NOPB
VIN
LM3404
GND
80V
V
IN
Module
Connector
Module
Connector
TVS
C
IN
Board Trace
Inductance
TVS or
smaller
zener diode
SNVS465F – OCTOBER 2006 – REVISED MAY 2013
Figure 29. VIN Pin with Additional Input Protection
GENERAL COMMENTS REGARDING OTHER PINS
Any pin that goes “off-board” through a connector should have series resistance of at least 1k
Ω
to 10k
Ω
in series
with it to protect it from ESD or other transients. These series resistors limit the peak current that can flow (or
cause a voltage drop) during a transient event, thus protecting the pin and the device. Pins that are not used
should not be left floating. They should instead be tied to GND or to an appropriate voltage through resistance.
cause a voltage drop) during a transient event, thus protecting the pin and the device. Pins that are not used
should not be left floating. They should instead be tied to GND or to an appropriate voltage through resistance.
Design Example 1: LM3404
The first example circuit will guide the user through component selection for an architectural accent lighting
application. A regulated DC voltage input of 24V ±10% will power a 5.4W "warm white" LED module that consists
of four LEDs in a 2 x 2 series-parallel configuration. The module will be treated as a two-terminal element and
driven with a forward current of 700 mA ±5%. The typical forward voltage of the LED module in thermal steady
state is 6.9V, hence the average output voltage will be 7.1V. The objective of this application is to place the
complete current regulator and LED module in a compact space formerly occupied by a halogen light source.
(The LED will be on a separate metal-core PCB and heatsink.) Switching frequency will be 400 kHz to keep
switching loss low, as the confined space with no air-flow requires a maximum temperature rise of 50°C in each
circuit component. A small solution size is also important, as the regulator must fit on a circular PCB with a 1.5"
diameter. A complete bill of materials can be found in
application. A regulated DC voltage input of 24V ±10% will power a 5.4W "warm white" LED module that consists
of four LEDs in a 2 x 2 series-parallel configuration. The module will be treated as a two-terminal element and
driven with a forward current of 700 mA ±5%. The typical forward voltage of the LED module in thermal steady
state is 6.9V, hence the average output voltage will be 7.1V. The objective of this application is to place the
complete current regulator and LED module in a compact space formerly occupied by a halogen light source.
(The LED will be on a separate metal-core PCB and heatsink.) Switching frequency will be 400 kHz to keep
switching loss low, as the confined space with no air-flow requires a maximum temperature rise of 50°C in each
circuit component. A small solution size is also important, as the regulator must fit on a circular PCB with a 1.5"
diameter. A complete bill of materials can be found in
at the end of this datasheet.
Copyright © 2006–2013, Texas Instruments Incorporated
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