The UC1854 provides active-power factor correction for power systems that otherwise woulddraw non-sinusoidal current from sinusoidal power lines. This device implements all the controlfunctions necessary to build a power supply capable of optimally using available power-line currentwhile minimizing line-current distortion. To do this, the UC1854 contains a voltage amplifier, ananalog multiplier and divider, a current amplifier, and a fixed-frequency PWM.
In addition, the UC1854 contains a power MOSFET-compatible gate driver, 7.5-V reference,line anticipator, load-enable comparator, low-supply detector, and overcurrent comparator.
The UC1854 uses average current-mode control to accomplish fixed-frequency currentcontrol with stability and low distortion. Unlike peak current-mode, average current controlaccurately maintains sinusoidal line current without slope compensation and with minimal responseto noise transients.
The high reference voltage and high oscillator amplitude of the UC1854 minimize noisesensitivity while fast PWM elements permit chopping frequencies above 200 kHz. The UC1854 is usedin single-phase and three-phase systems with line voltages that vary from 75 V to 275 V and linefrequencies across the 50-Hz to 400-Hz range. To reduce the burden on the circuitry that suppliespower to this device, the UC1854 features low starting supply current.
These devices are available packaged in 16-pin plastic and ceramic dual in-line packages,and a variety of surface-mount packages.