Typical application for LED driver with temperature compensation

LED lighting drive technology has been applied to all aspects of power supply technology, and LED technology has begun to mature, many more advanced technologies have begun to join, this article will be a typical application of lib-LED drive controller with temperature compensation. Interested friends will come and have a look.
The SN3910 is an AC/DC dual-purpose temperature compensated dimmable HB-LED (High Brightness LED) drive controller suitable for driving HB-LED lighting. The typical application circuit of the SN3910 using AC power supply is shown in Figure 1. AC input voltage U=220V±15%. FU is a 1A/250V fuse tube, and RNTcl is a current limiting resistor when the power is turned on. C is a line-causing capacitor that suppresses series mode interference. The rectifier bridge is composed of four 1N4007 type 1A/1000V silicon rectifier tubes. In order to improve the power factor, a second-order valley-filled PFC circuit is constructed by using VD-VD, C, and C. RNT2 uses l00kQ (TA=25°C) negative temperature coefficient thermistor. R uses a 1.0Q precision resistor with an adjustable resistor R (100Q) in parallel with both ends.

figure 1

The temperature compensation starting point of the SN3910 and the slope of the output current drop can be set by R and R. The principle of temperature compensation is as follows: First, the reference voltage U of 1.2V is supplied from the E pin, and then grounded through the resistor dividers RT1I and R. Connect the midpoint of the resistor divider to the LD pin and set its voltage to be related:

Analysis of equations (1) and (2) shows that when the ambient temperature T increases, R. The resistance value decreases rapidly.
Once U<0.24V, the temperature compensation function is activated, and the output current is reduced by the internal circuit of the SN3910, and the average current is also reduced, thereby achieving the purpose of temperature compensation.