Datasheet

+
+
100
90
80
70
60
50
10 15 20 25 30
Efficiency (%)
Input Voltage (V)
TPS40200
www.ti.com
SLUS659F FEBRUARY 2006REVISED MARCH 2012
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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