Semtech Corp. (Newbury Park, CA) has unveiled two new devices intended for use in distributed power architectures in telecommunications, data processing, point-of-use industrial systems, space-sensitive switching power supplies and other applications. The SC4820 devices are low-power PWM controllers intended for power conversion using push-pull or bridge topologies, typically in point-of-use off-line or dc/dc fixed-frequency, current-mode switching power supplies.
The SC4820s come in industry-standard SO-8 packaging. Intended for converting a typical 18V to 75V telecommunications supply rail to a 12V supply rail, the SC4820 controller is adaptable to other input voltage ranges. Semtech claims that the new SC4820 devices provide improved efficiency and utilization of the power transformer, as well as providing 250kHz and 500kHz trimmed switching frequencies.
"The SC4820 devices expand Semtech's power-management device portfolio, sustaining our committed push to provide superior products for power supply engineers in the telecommunications industry," said George Georgalis, director of power-management products at Semtech. "These highly-integrated, eight-pin, push-pull current-mode controllers can be used to simplify, reduce costs and shrink the board space required for new designs."
Other valuable features of the SC4820 controllers include current-mode topology with slope compensation, cycle-by-cycle current limiting to prevent core saturation and to provide fast transient response and low voltage, and fully differential internal logic for high-frequency, low-noise operation. Additionally, the devices have a direct drive for N-channel MOSFETs with nonoverlap protection and a 1A peak drive-current capability, as well as under-voltage lockout with user-programmable hysteresis, internal soft-start and dead-time control, and adaptive leading-edge blanking. Also, both devices have precise thermal shutdown.
Semtech's new devices and evaluation boards are currently available for sampling. Production volumes shipped in tape and reel packaging will be available in December 2000. The devices are priced at $2.08 in 1,000-piece OEM quantities.
