ML4812IQX

ML4812IQX application field and working principle

ML4812IQX is a highly integrated CMOS power factor correction (PFC) controller specially designed to reduce total system cost and minimize the size of power converter used in AC/DC converters with the novel valley switching topology. It integrates functions such as PFC, peak current sensing, over-voltage protection, load regulation, feedback calculation and other control algorithms for a complete PFC solution. It features high integration, low cost and low system noise as well as high reliability.

The application area of ML4812IQX mainly reflects in the Led lighting application, it provides a superior PFC solution for LED light drives such as LED spotlights, LED down lights, LED modules, etc. It also can be suitable for a variety of applications including ac/dc open frame power supplies, adapter, lighting product and so on.

Working principle

ML4812IQX applies valley-switch topology controls the single-ended power factor correction (SEPFC) converter and achieves constant power output. The parameters are controlled through modulation of the switch on/off time and regulated by the input voltage (VIN) and peak current (IPK) sensing. The IRS21357 IC is integrated within the ML4812IQX, which simplifies the external peripheral components.

The consecutive valley-switched current mode operation of valley switch allows average power, not just pulse-width-modulated, current to flow in the inductor, resulting in an output voltage of constant power, lowered power losses in passive components and reduced harmonic content. The topology achieves high efficiency without an input EMI filter compared to discontinuous conduction mode (DCM) or continuous conduction mode (CRM).

In addition, built in the SEPFC driver is an internal slope resistor, an internal MOSFET driver, VSENSE, high and low side gate drivers, signature protection, and a multi-level hysteretic voltage mode controller. The ML4812IQX can be set in STB or OVP mode with a high switching frequency of up to 500 kHz and high power density.

Conclusion

ML4812IQX is a novel power factor correction (PFC) controller which integrates many functions and offers superior performance for LED lighting drives, AC/DC open frame power supplies, adapter, lighting product and so on. It features high integration and low cost and also features low system noise, high reliability and high efficiency. Built-in various protection and hysteretic voltage mode controller further improves the stability and reliability of the PFC circuit.