January 22, 2014 – Linear Technology Korea (CEO Hong Sa-kwak) announced the launch of a dual output current mode synchronous step-down DC/DC controller (product name: LTC3875). This product employs an innovative DCR sensing architecture that improves the signal-to-noise ratio of current sensing signals, enabling the use of very low DC resistance (DCR) power inductors. Power inductors with DCR as low as 0.2 milliohms can be used without sense resistors to maximize converter efficiency and increase power density. This new DCR sensing technique dramatically reduces switching jitter typically associated with low DCR sensing applications.

The LTC3875 operates within an input voltage range of 4.5V to 38V and generates fixed output voltages ranging from 0.6V to 3.5V with +/-0.5% accuracy at -40°C to 125°C. Dual onboard differential amplifiers provide true remote output voltage sensing at all output voltages. Up to 12 phases can be configured in parallel, with phase-staggered clocks minimizing filtering requirements at the input and output stages. When two outputs are paralleled, the LTC3875 maintains inter-phase current mismatch of less than +/-5%, making it ideal for very high current requirements up to 360A. Precision programmable current sense limiting and DCR temperature compensation precisely limit maximum output current across the full operating temperature range. Applications include high current power distribution, redundant (n+1) power supplies, industrial systems, processor and ASIC power supplies.

The LTC3875 can select a fixed operating frequency in the range of 250kHz to 720kHz or be synchronized to an external clock. A robust 1.1 Ohm onboard N-channel gate driver minimizes MOSFET switching losses. Adjustable current limiting can be configured with very low sense voltages in the range of 10mV to 30mV to minimize power losses. Channel 2 provides fast transient response characteristics with up to 30% load step-up transient overshoot. Additional features include adjustable soft-start or tracking, foldback current limiting, short-circuit soft recovery, output overvoltage protection, and power good output voltage monitoring.

Photo caption: Sub-milliohm Current Mode Dual Step-Down DC/DC Controller