An LED backlight device consists of the boost converter that supplies LED strings
with the voltage of rating and the constant current driving section that maintains the
light of each LED string stable. To minimize the electric consumption at the constant
current driving section, the voltage drop at the channel constant current driving section
of each LED string must be kept minimized. Due to such factors as difference in VF of
high output LED applied to LED strings and characteristic changes at different
temperatures, the voltage drop at the constant current driving section of each channel of
the LED backlight device results in difference between channels. When excessively
high voltage is input, the voltage drop at the channel constant current driving section is
accelerated, which requires more electric consumption. In contrast, when excessively
low voltage is input, the constant current driving becomes impossible. Thus, to realize
an LED backlight device with excellent electric consumption efficiency, the output
voltage of the boost converter must be controlled to the extent that the constant current
driving is possible by minimizing the electric consumption at the channel constant
current driving section and by managing the voltage of each channel to the lowest [3].