Step-down regulator can be used for multi-rail systems

Adjustable from 14.5V down to 0V output with a single resistor, the LTC3623 is a ±5A high efficiency, current mode synchronous buck regulator from Linear Technology. Its architecture uses a 50microA current reference, combined with a single resistor, to set the output voltage. The design enables easy current sharing between multiple regulators, explains the company, setting the output voltage for all of the regulators with a single external resistor. The bipolar ±5A sink and source capability, wide VIN and VOUT capability, current mode control for tight line and load regulation, high efficiency, low external parts count and parallel capability make it suitable for multi-rail systems, as well as tracking supplies, ASIC substrate biasing, DDR memory supplies, point-of-load power supplies, portable instruments, distributed power supply systems, battery-powered equipment and thermo electric cooler systems.

The wide 4.0 to 15V input voltage range is ideal for dual-cell Li-Ion applications, and fixed 5.0 and 12V intermediate bus systems. Low RDS(ON) integrated N-channel power MOSFETs and synchronous rectification deliver efficiencies as high as 96 per cent.  The design allows dynamic adjustment of output voltage from 0V to VIN  to 0.5V, offering virtually rail-to-rail performance, says the company. The ability to sink up to 5A down to 0VOUT enables it to power down individual rails in the system as needed. Its on-chip trimmed reference achieves high accuracy of ± one per cent.  Output regulation and transient response are independent of output voltage. The user can directly drive the ISET pin with an external voltage supply to program the converter’s VOUT. Output voltage tracking or soft-start is programmed via the ISET pin for applications that require power sequencing.

The 400kHz to 4MHz switching capability enables the use of tiny, low cost capacitors and inductors, and combined with its compact QFN package, offers a compact footprint for multi-rail applications. There is also programmable wire drop compensation, an input supply voltage regulation loop for extracting power from high impedance sources such as solar panels, an output current monitor, a power good voltage monitor, external synchronization capability and thermal protection.

The regulator is available in a thermally enhanced, 24-lead 3.0 x 5.0mm QFN package, with both E and I grades specified for an operating junction temperature of –40C to +125 degree C.

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