60V, 4A step-down inverting output regulator is single-resistor programmable

April 10, 2016 // By Graham Prophet
LTC7149 is a high efficiency, 60V, 4A synchronous buck regulator for negative output voltage supplies. It incorporates a current mode architecture with user-selectable internal or external loop compensation and an output voltage that is programmed with a single external resistor.

The regulator operates from an input voltage range of 3.4V to 60V and provides an adjustable output voltage from 0V to -28V, while delivering up to 4A of continuous output current. Its wide input and output voltage ranges suit it for test, measurement and industrial applications. The LTC7149’s design includes an accurate internally generated 50 µA current source on the ISET pin that enables it to deliver outputs as low as -28V with the use of a single external programming resistor. IT offers ±0.8% output voltage accuracy. Its switching frequency is user programmable from 300 kHz to 3 MHz, enabling the use of small, low cost capacitors and inductors. Combined with a 28-lead 4 x 5 mm QFN or thermally enhanced TSSOP package, it offers a compact footprint.


The LTC7149 uses internal switches with R[DS(ON)] of 110milliOhms and 50milliOhms to deliver efficiencies as high as 92%. Burst Mode operation offers high efficiency at light loads, requiring only 440 µA of quiescent current. For noise sensitive applications, the LTC7149 can run in forced continuous mode, offering very low output ripple. It also includes ground-referenced clock and PGOOD pins, eliminating the need for level shifters. Additional features include a power-good voltage monitor, programmable wire drop compensation, external synchronisation capability and thermal protection.


The LTC7149EUFD is available in a 4 x 5 mm QFN-28, and the LTC7149EFE is offered in a 28-lead, thermally enhanced TSSOP package. Industrial grade versions, the LTC7149IUFD and LTC7149IFE, operate over the -40°C to 125°C operating junction temperature range. Pricing starts at $5.65 (1,000).


Linear Technology; www.linear.com/product/LTC7149