Date: 22/09/2010

Dual-channel dual-phase synchronous buck controller from National Semiconductor with ECM control

National Semiconductor has released the LM5119, a dual-channel, dual-phase, synchronous buck controller with emulated current-mode (ECM) control. The LM5119 enables regulation of single or dual high-current voltages directly from inputs as high as 65V. National semiconductor says that this buck controller simplifies DC/DC conversion and reduces PCB footprint by up to 50 percent versus alternative solutions requiring two conversion stages. The LM5119 enables direct regulation of two output voltages from an input, eliminating the need for an intermediate bus conversion stage.

National's ECM control technology enables control of small duty cycles necessary in high voltage applications, which allows accurate regulation of DC output voltages with good transient response. For high-current output requirements, the two outputs can be connected in parallel to power loads up to 40A with interleaved switching that minimizes input and output capacitance.

National's LM5119 operates over a voltage range of 5.5V to 65V and enables accurate regulation of load voltages from 0.8V up to 90 percent of the input voltage. The operating frequency is user-programmable from 50 kHz up to 750 kHz and can be synchronized to an external clock signal. The buck controller features Diode emulation mode (DEM), which enables discontinuous inductor current operation at light load conditions. The DEM allows controlled start-up into a pre-biased load by preventing current flow into the synchronous MOSFET. The LM5119 also provides high voltage bias regulator with automatic switch-over to external bias. The LM5119 also features thermal shutdown, cycle-by-cycle and hiccup mode current limit and adjustable line under-voltage lockout. The buck controller provides wide Vin range, multi-phase operation, programmable soft-start, input UVLO and diode emulation mode.

Package: 5 mm by 5 mm 32-pin LLP

Price:
LM5119: US$4.05 for 1K pieces.
LM25119:US$3.80 for 1K pieces