Power Factor Controllers
The MC34262/MC33262 are active power factor controllers
specifically designed for use as a preconverter in electronic ballast
and in off−line power converter applications. These integrated
circuits feature an internal startup timer for stand−alone applications,
a one quadrant multiplier for near unity power factor, zero current
detector to ensure critical conduction operation, transconductance
error amplifier, quickstart circuit for enhanced startup, trimmed
internal bandgap reference, current sensing comparator, and a totem
pole output ideally suited for driving a power MOSFET.
Also included are protective features consisting of an overvoltage
comparator to eliminate runaway output voltage due to load removal,
input undervoltage lockout with hysteresis, cycle−by−cycle current
limiting, multiplier output clamp that limits maximum peak switch
current, an RS latch for single pulse metering, and a drive output high
state clamp for MOSFET gate protection. These devices are
available in dual−in−line and surface mount plastic packages.
