Quad-output regulator has low voltages covered

Edited by the Electronicstalk editorial team May 8, 2003

A new highly efficient regulator combines two linear and two switching controllers, all programmable, to meet the market's need for providing multiple low output voltages.

A new highly efficient regulator combines two linear and two switching controllers, all programmable, to meet the market's need for providing multiple low output voltages.

The SC2453 manufactured by Semtech combines two low-dropout (LDO) regulators - one positive and one negative - and two highly efficient synchronous, voltage-mode, buck switching regulators.

The devices input voltage can range from 4.5 to 30V, thus encompassing 5, 12 and 24V power supply buses, or any bus within the 4.5-30V range.

The SC2453's output can go as low as 0.5V and supply up to 20A through external mosfets.

Packaged in a tiny TSSOP-28, the SC2453 also features a programmable switching frequency up 700kHz, reducing the size and number of capacitors and inductors required.

Additionally, the two switching regulators, designed to drive N-Channel mosfets, are synchronised to avoid beat frequencies, and fixing the switching frequency to one value simplifies filtering and EMI suppression.

Also, by switching 180 degrees out of phase with each other the switching regulators reduce input ripple.

Power-up sequencing avoids latchup problems.

For added efficiency, the SC2453 eliminates the need for a current sensing resistor.

Additional features include overcurrent protection with adjustable current limit, fast transient response bootstrapping for high-side mosfets, soft start operation, and "power good" output signal.

Available from Pulsar with an operating temperature range of -40 to +105C, the SC2453 lends itself to cost-sensitive mixed-signal products needing both positive and negative voltages, such as set-top boxes, wireless basestations, switching power supplies and broadband modems.