Synchronous step-down DC-DC converter delivers high efficiency

Linear Technology has announced the LTC3126, a 2.5A, 42V synchronous step-down switching regulator with an integrated dual input PowerPath control. A unique power stage topology enables operation from either of two independent power sources, with seamless, internally controlled transitions between inputs to ensure a stable output voltage during hot-plug and power source disconnect events. Internal power switches and synchronous rectification combine to deliver 95% efficiency over a wide voltage range, enable a fast transient response and ensure excellent loop stability while switching at 2MHz. This allows designers to avoid critical noise-sensitive frequency bands such as AM radio, while providing a highly compact solution footprint. The device’s current mode topology is internally compensated, eliminating the need for external compensation components. Burst Mode operation maintains high efficiency at low output currents while keeping peak-to-peak output ripple below 1%. Further, it features a quiescent current under 2µA in no-load standby conditions, ideal for always-on systems and portable applications. The device’s wide 2.4V to 42V input and 0.818V to VIN output voltage ranges are well suited for automotive applications which must regulate through cold-crank, load dump and stop-start scenarios. Other key applications include portable industrial/communications test equipment, battery and supercapacitor backup power systems, automotive power with battery backup, uninterruptible power supplies, and systems powered by unregulated wall adapters or single to multicell stacks of most battery chemistries. The device’s integrated lossless PowerPath circuitry supports seamless operation from two separate input power sources. Pin-selectable ideal diode-OR and priority input modes with user-programmable undervoltage lockout thresholds provide full control over the transition between the input power sources. The fast, automatic switchover provided by this internal PowerPath eliminates the need for hold-up capacitors and minimises disturbances on the output rail. An active input channel indicator and independent input and output power good signals provide complete feedback of the power system status. Other features include 1µA current in shutdown, internal soft-start and thermal protection.