6A step-down DC/DC allows ±25% voltage margining to 0.1%

December 21, 2015 // By Graham Prophet
LTC3815 is a high efficiency 6A monolithic synchronous step-down DC/DC converter with an I²C-based PMBus interface for digital power system management (PSM), that provides programming and read back of voltage, current, temperature and faults; via LTpowerPlay software the interface allows the output voltage to be margined over a ±25% range with 0.1% resolution.

The LTC3815’s simplified and intuitive PMBus “Lite” command set makes it simple to use. The default output voltage is set with a single external resistor and will power up to this voltage with or without the serial interface. This monolithic device for lower current applications has input operating supply voltage range of 2.25V to 5.5V making it suitable for operation from 2.5V, 3.3V or 5V rails or from Llithium-Ion batteries. The output voltage is programmable from 0.4V to 72% of V IN or can be set with an external voltage reference for intelligent energy power conversion, ASIC/FPGA power, distributed power and point-of-load applications.

The LTC3815 uses a phase-lockable controlled on-time, current mode architecture providing fast transient response and enabling operation at the low duty cycles necessary to regulate low output voltages at high switching frequencies. The operating frequency is programmable from 400 kHz to 3 MHz with an external resistor or for switching noise sensitive applications, it can be synchronised to an external clock over the same range.

An integrated differential amplifier provides true remote output voltage sensing enabling high accuracy regulation, independent of board IR voltage drops. Additional features include a clock output for 2-phase operation, a power good signal, selectable forced continuous or discontinuous mode and a 1 msec start-up time.

The LTC3815 is available in a 38-lead 4 x 6mm QFN package with an operating junction temperature range of -40°C to 125°C for $4.71 (1000).

Linear Technology; www.linear.com/product/LTC3815