Datasheet
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InputVoltage-V
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TPS40200-EP
www.ti.com
SGLS371A –JANUARY 2007–REVISED JANUARY 2013
Application 3: Wide Input Voltage LED Constant-Current Driver
This application uses the TPS40200 as a buck controller that drives a string of LED diodes. The feedback point
for this circuit is a sense resistor in series with this string. The low 0.7-V reference minimizes power wasted in
this resistor, and maintains the LED current at a value given by 0.7/R
SENSE
. As the input voltage is varied, the
duty cycle changes to maintain the LED current at a constant value so that the light intensity does not change
with large input voltage variations.
Figure 47. Wide Input Voltage-Range LED Driver
Figure 48. Efficiency vs Input Voltage
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