10A Integrated FET Regulator with Programmable LDO

Date: 13/3/2009

10A Integrated FET Regulator with Programmable LDO

The SC417 is a stand-alone synchronous buck power supply that features integrated power MOSFETs, a bootstrap switch, a programmable LDO and innovative power-saving features in a space saving MLPQ-5x5mm 32-pin package.

The new device has a wide input voltage range of 3V to 28V and achieves high efficiencies over an extended load range. The SC417 is first device in a new Semtech family of high current point-of-load voltage regulators. The second device, the SC427 with regular power save (no frequency floor), is due for release later in ‘Q1.


Semtech has announced the first device in a new family of high current point-of-load voltage regulators. The SC417 is a stand-alone synchronous buck power supply that features integrated power MOSFETs, a bootstrap switch, and a programmable LDO in a space saving MLPQ-5x5mm 32-pin package.The new device has a wide input voltage range of 3V to 28V and achieves high efficiencies over an extended load range.


The SC417 features temperature-compensated RDS(ON) sensed current limit, which effectively doubles the current limit precision and has built-in soft-start, cycle-by-cycle current limiting, over-temperature, and over- and under- voltage protection features. It also includes a power good output for the switching regulator which may be used for diagnostics and sequencing and a programmable LDO that provides the 5V necessary for the gate drive bias, allowing the device to operate from a single rail. For optimum efficiency the internal crossover circuitry bypasses the LDO after startup if the LDO and buck outputs are the same. 

The SC417 offers a range of advanced power-save functions: Selectable ultrasonic power save allows the device to operate in discontinuous conduction mode at light load conditions, saving quiescent current, while limiting the 'floor' frequency to avoid audible noise. Smart Power Save enables the devices to re-enter continuous conduction mode when active loads attempt to pull the output high while in power save mode, pulling the output back down and avoiding over voltage latch-off.

Pseudo fixed frequency adaptive on-time control gives the SC417 good transient response, reduces the output filter capacitance required and greatly simplifies the design process by removing external compensation components. Semtech's SmartDrive technology reduces EMI and eliminates snubbing components and gate drive resistors. .
The second device in the SC4x7 family, the SC427, with regular power save (no frequency floor) is due for release later in ‘Q1. 
 
Applications
• Notebook, desktop, tablet, and server computers
• Networking and telecommunication equipment
• Printers, DSL, and STB applications
• Embedded applications
• Power supply modules
• Point of load power supplies