Low-cost miniature push-pull voltage controller

Edited by the Electronicstalk editorial team Jul 16, 2001

New from Semtech, the SC4820 is a low-power pulsewidth modulator (PWM) controller intended for power conversion using push-pull or bridge topologies.

New from Semtech, the SC4820 is a low-power pulsewidth modulator (PWM) controller intended for power conversion using push-pull or bridge topologies, typically in point-of-use offline or DC/DC fixed-frequency, current-mode switching power supplies.

Optimised for space- and cost-conscious system designs, the robust SC4820 controller's abundant features belie its small SO-8 packaging.

Intended for converting a typical 18-75V telecommunications supply rail to a 12V supply rail, the SC4820 controller is easily adapted to other input voltage ranges.

In an example application, the 12V output from the SC4820 controller could be converted to two separate high-efficiency regulated low-voltage supplies (3.3, 5V etc), using a device such as Semtech's complementary dual output SC2420 biphase/dual-channel secondary-side controller.

The new SC4820 devices provide improved efficiency and usage of the power transformer, as well as providing 250kHz (SC4820A) and 500kHz (SC4820B) trimmed switching frequencies.

"The SC4820 devices expand Semtech's power management device portfolio, sustaining our committed push to providing 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 cost, and shrink the board space required for new designs".

Other features of the SC4820 controllers include: cycle-by-cycle current limiting to prevent core saturation and provide fast transient response; low voltage, fully-differential internal logic for high-frequency, very-low-noise operation;?direct drive for N-channel mosfets with nonoverlap protection and 1A peak drive current capability;?undervoltage lockout with user programmable hysteresis;?internal soft start and dead-time control; adaptive leading edge blanking;?and precise thermal shutdown.

The SC4820 devices are assembled in low-profile compact SO-8 packages, and devices and evaluation boards are sampling now.

The devices are priced at $2.08 in 1000 piece OEM quantities.