Buck and boost regulator combines LDO controller

Linear Technology has announced the LT3570, a 36V, 1.5A (ISW) buck and boost regulator combined with a linear controller packaged in a 4mm x 4mm QFN or TSSOP-20E.

The LT3570 operates from a VIN range of 2.5V to 36V (40V max), making it suitable for the load dump and cold-crank conditions found in automotive applications.

Independent input pins can be tied together to run from a single input or can be run from independent input rails.

The buck regulator can deliver up to 1A of continuous output current at voltages as low as 0.8V, whereas the boost converter can deliver output voltages as high as 38V.

The LDO controller combined with an external NPN transistor can be run from the output of the buck regulator for maximum efficiency or via an independent input pin for design flexibility, either way providing low-noise operation.

Switching frequency is user programmable from 500kHz to 2MHz and can be synchronised from 650kHz to 2.5MHz.

The combination of its 4mm x 4mm QFN package (or thermally enhanced TSSOP-20) and high switching frequency, which keeps external capacitors and the inductor small, provides a compact, thermally efficient footprint.

Both the LT3570's buck and boost switchers utilise 1.5A, 240mV Cesat switches, with the necessary oscillator, control, logic circuitry and LDO controller integrated into a single die.

Special design techniques enable efficiencies of up to 88 per cent over a wide input voltage range while current mode topology enables fast transient response and excellent loop stability, according to the company.

Other features include independent soft-start capability for each channel and thermal shutdown.

The LT3570EUF is packaged in a 4mm x 4mm QFN, while the LT3570EFE comes in a thermally enhanced TSSOP-20 package.

The LT3570IUF and LT3570IFE are tested and guaranteed to operate from a -40C to 125C junction temperature.

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