Datasheet AP1910 (Anwell Semiconductor) - 6

AP1910 Anwell Semiconductor Corp. Detail Description
The AP1910 is a low-cost buck, boost or
Supply Current
buck-boost converter controller specifically designed for driving multi LED strings or arrays. It A current of 0.2mA is needed after start up the can be operated from either universal 90~264Vac AP1910 controller. This current is generated from or DC voltage between 20 and 450Vdc. The internal HV regulator circuit. The AP1910 without AP1910 can also drive multiple strings of using bulky startup resistors typically required in High-Brightness (HB) LEDs. The AP1910 could the offline applications. Moreover, in many regulate constant current to ensure controlled applications using AP1910 can be continuously brightness and spectrum of the LEDs. Constant powered because of its internal linear regulator current driving method can also improve LEDs that provides a regulated voltage of 7.5V for lifetime. The AP1910 supports soft start function internal circuits. The IC power consumption is to reduce inrush current. It can add resistor from very low when high line input voltage because of VDD to LD pin to generate 1~5uA current and low operating current. charge LD capacitor. The voltage level will rising with slop and correspond to CS pin current limit level. The IC has feed-forward compensation by
Current Sense
setting suitable resistor in CS pin to keep LED string constant current when line voltage variation. The current sense input of the AP1910 goes to the non-inverting inputs of two comparators. The The AP1910 include an internal high voltage linear inverting terminal of one comparator is tied to an regulator to generate fix VDD voltage supply to IC internal 245mV reference whereas the inverting internal logic circuit. terminal of the other comparator is connected to the LD pin. The outputs of both these
LED Driver Operation
comparators are fed into an or gate and the output of the or gate is fed into the reset pin of the flip-flop. The AP1910 controls all basic types of converters, Thus the comparator which has the lowest voltage non-isolated, operating in continuous or at the inverting terminal determines when the discontinuous conduction mode. N-MOSFET is GATE output is turned off. turned on when PIN GATE is high, and the input energy is delivered to LED driver and stored in an The outputs of the comparators also include a inductor. The energy is stored in the inductor free 500ns blanking time due to the turn on spike wheeling itself through the string of LEDs when current. Some solution will add RC filter to power switch off. prevent this situation. When the VDD pin voltage exceeds the UVLO threshold, the internal power switch is enabled.
Linear Dimming
The output current is controlled by mean of limiting peak current of CS pin. The peak current limit The AP1910 has two type dimming functions. level is set by LD pin of the AP1910. The Linear dimming is setting LD pin voltage level to adjust current limit. The AP1910 using Buck topology needs to design the duty cycle below 50% to prevent unregulated Gate output pulse. It can apply resistor between
PWM Dimming
RT and Gate pin. That is constant off time function when duty over 50%. PWM dimming can be achieved by driving the PWMD pin with a low frequency square wave signal. When the PWM signal is zero, the GATE driver is turned off and when the PWMD signal if high, the GATE driver is enabled. On the other hand, the GATE driver is disabled. All reserved by AnSC © 2012 Page: 6/11 V1.6-2014/09/29