Engineering 101

Regulator enables easy current sharing

A ±5A high efficiency, current mode synchronous buck regulator that is adjustable from 14.5 down to 0V output with a single resistor, the LTC3623, has been announced by Linear Technology. Proven on Linear Technology’s prior linear and switching regulators, the LTC3623 uses a 50µA current reference, combined with a single resistor, to set the output voltage.

Its unique design enables easy current sharing between multiple regulators, setting the output voltage for all of the regulators with a single external resistor. The LTC3623’s 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 ideal for modern multirail systems, in addition to 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 LTC3623’s wide 4 to 15V input voltage range is ideal for dual-cell Li-Ion applications, and fixed 5 and 12V intermediate bus systems. Low RDS(ON) integrated N-channel power MOSFETs and synchronous rectification deliver efficiencies as high as 96%. The device’s novel design allows dynamic adjustment of output voltage from 0V to VIN – 0.5V, offering virtually rail-to-rail performance. The LTC3623’s 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 ±1%. Furthermore, output regulation and transient response are independent of output voltage. The user can directly drive the LTC3623’s ISET pin with an external voltage supply to program the converter’s VOUT. Additionally, output voltage tracking or soft-start is easily programmed via the ISET pin for applications that require power sequencing.

The LTC3623’s 400kHz to 4MHz switching capability enables the use of tiny, low cost capacitors and inductors, and combined with its compact QFN package, offers a very compact solution footprint for multirail applications. Additional device features include: 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 LTC3623 is available in a thermally enhanced, 24-lead 3x5mm QFN package, with both E and I grades specified for an operating junction temperature of –40 to 125°C. Devices are in stock, and pricing for the E grade starts at $3.95 each in 1,000-piece quantities.

Summary of features: LTC3623

  • single resistor programmable VOUT: 0V to VIN – 0.5V
  • ISET accuracy: ±1%
  • tight VOUT regulation across VOUT range
  • output current monitor accuracy: ±5%
  • programmable wire drop compensation
  • easy to parallel for higher current and heat spreading
  • input supply voltage regulation loop
  • high efficiency: up to 96%
  • output current: ±5A
  • integrated power N-MOSFETs (60mΩ top and 30mΩ bottom)
  • adjustable switching frequency: 400kHz to 4MHz
  • VIN range: 4 to 15V
  • current mode operation for excellent line and load transient response
  • shutdown mode draws less than 1µA supply current
  • thermally enhanced, 24-Lead 3×5mm QFN package

Available downloads:

Linear Technology LTC3623 datasheet

Comments are closed, but trackbacks and pingbacks are open.