At present, light-emitting diode drive chips can be divided into: constant voltage drive chips, constant current drive chips, and pulse drive chips. Among them, the constant voltage drive chip is generally our common DC/DC boost chip. The advantage of this scheme is that the chip cost is cheap and there is no complicated peripheral circuit. But only driving the LED with a constant voltage will cause uncontrollable circuit current when driving the output. The consistency of LED brightness cannot be guaranteed.
The constant current drive chip solves the current uncontrollable problem of the previous constant voltage drive. The current relatively good constant current chip can achieve a constant current accuracy of about 1%, and it has a simple peripheral control interface that can flexibly set the required output current, so it is very popular. But the price of this kind of chip is much higher than that of the constant voltage chip and the peripheral circuit is complicated. At the same time, because of the constant output current, the entire chip discharges faster when the battery is used as power supply.
At present, the pulse-type driving chip supplies power to the LED lamp with a high-frequency pulse generator output interface. Because the frequency of the pulse signal is very high, the human eye cannot feel the stroboscopic LED at all, so this method not only meets the visual needs, but also effectively saves the power output on the one hand. And the operating frequency of this type of chip can generally be controlled by an external interface. However, the current oscillation frequency of this type of chip is generally in the range of 100KHz~500KHz. Therefore, the current drive capability is only suitable for low-power applications. However, it is believed that it will be promoted to high-power LED driving occasions in the near future.
