At present, light-emitting diode drive chips can be divided into: constant-voltage drive chip, constant-current drive chip and pulse-type drive chip. One of the constant pressure-type drive chip is generally our common DC boost chip majority. The advantage of this scheme is that the chip is inexpensive without complex peripheral circuits. However, only a constant voltage-driven LED will cause the output circuit current is not controllable.
Can not guarantee the consistency of LED brightness. Constant-current drive chip solves the problem that the current is not controlled by constant-voltage drive. At present, the better constant current chip can do 1% of constant current accuracy, and a simple peripheral control interface can be flexibly set the required output of the current size so much welcome. But this kind of chip price is much higher than the constant voltage chip price and the periphery circuit is complex.
At the same time because the constant output current, the entire chip in the battery as a power supply when the discharge will be relatively fast. At present, the pulse-type drive chip is a high-frequency pulse generator output interface to the LED lamp power supply. Because the pulse signal is very high frequency, so the human eye can not feel the strobe, so this way is in line with the visual needs and in the one hand effectively save energy output. and the working frequency of this type of chip can be controlled by external interface generally. But at present, the frequency of this type of chip oscillation is generally in 100khz~500khz range. So the current drive capability is only suitable for small power applications. But I believe that in the near future will be upgraded to high-power led driver occasions.