3.3A, 2.5MHz, 42V Boost/Inverting DC/DC Converter with Fault Protection

Linear Technology Corporation announces the LT3581, a current mode, fixed frequency step-up DC/DC converter with integrated fault protection features for output shorts, input/output overvoltages, and overtemperature conditions. The LT3581 uses two integrated 42V switches – a 1.9A master switch and a 1.4A slave switch – which can be tied together for a total limit of 3.3A. The LT3581 operates from an input voltage range of 2.5V to 22V, with transient protection to 40V, making it suitable for applications with input sources ranging from a single-cell Li-Ion to automotive inputs. The LT3581 is ideal for many local power supply designs as it can be configured as either a boost, SEPIC or an inverting converter. The combination of a 4mm x 3mm DFN package (or MSOP-16E) and tiny externals ensures a very compact footprint while minimizing solution cost.

The LT3581's low VCESAT switches, 0.25V (tied together at 2.75A), deliver efficiencies up to 88%. With both switches combined and from a 5V input, the LT3581 can deliver up to 830mA at 12V or 625mA at -12V. For high voltage outputs, the LT3581's slave switch enables high power charge pump topologies which are very efficient and require few external components. The LT3581's switching frequency can be programmed via a single resistor or synchronized to an external clock between 200kHz and 2.5MHz, minimizing external component sizes and avoiding “noise critical” frequency bands. Undervoltage 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 and junction temperature monitoring