Current-mode fixed-frequency step-up DC-DC converters operate from 2.55V to 40V

Linear Technology has introduced the LT8570 and LT8570-1 current mode, fixed frequency step-up DC-DC converters. The LT8570 uses an internal 500mA, 65V switch, whereas the LT8570-1 uses a 250mA, 65V switch. Both devices operate from an input voltage range of 2.55V to 40V, making them suitable for applications with input sources ranging from a single-cell Li-Ion to automotive inputs. Both the LT8570 and LT8570-1 can be configured as a boost, SEPIC or inverting converter. The LT8570-1’s smaller switch enables the use of a smaller inductor in lower current applications. Both parts offer a programmable switching frequency between 200kHz and 1.5MHz, enabling designers to minimize external component sizes. The combination of a 3mm x 3mm DFN package (or MSOP-8E) and tiny externals ensures a very compact footprint while minimizing solution cost. The LT8570 and LT8570-1 use internal high efficiency switches, which deliver efficiencies up to 86%. Under-voltage lockout (UVLO) is user adjustable for optimal system performance. A single feedback resistor sets the output voltage, minimizing external components. Other features include external synchronization capability, internal soft-start, thermal shutdown protection and the ability to work in inverting and SEPIC applications. The LT8570/-1 is available in both a 3mm x 3mm DFN-8 and a thermally enhanced MSOP-8 package. Two temperature grades are available, with operation from -40C to 125C (junction) for the extended and industrial grades, says the company.