LTC3649 is a new high-efficiency, 60V / 4A synchronous buck regulator from Linear Technology. The device uses a constant frequency current mode architecture with programmable output current and output voltage, which can be set by a single external resistor.
The LTC3649 operates from an input voltage range of 3.1V to 60V and provides an adjustable rail-to-rail output voltage range from 0V to 0.5V below VIN, while providing continuous output current up to 4A. Its wide input and output voltage range is ideal for a variety of test, measurement and industrial applications. The unique design of the LTC3649 includes an accurate internally generated 50µA current source on the ISET pin, enabling it to use an external programming resistor to provide an output as low as 0V.
In addition, the LTC3649 provides ± 0.8% output voltage accuracy and programmable output current with ± 4% accuracy without the need for a sense resistor. Users can program their switching frequency from 300kHz to 3MHz, allowing the use of tiny, low-cost capacitors and inductors. The LTC3649, combined with a 28-lead 4mm x 5mm QFN package or a thermally enhanced TSSOP package, provides a compact solution that takes up board area.
The LTC3649 uses internal power switches with RDS (ON) of only 100mohm and 50mohm to provide up to 95% efficiency. Burst mode operation provides high efficiency at light loads, requiring only 440µA of quiescent current. For noise sensitive applications, the LTC3649 can operate in forced continuous mode, providing very low output ripple. Other features include ± 4% accurate output current monitoring, power good voltage monitor, programmable line drop compensation, external synchronization function and thermal protection.
The LTC3649EUFD is available in a 4mm x 5mm QFN-28 package, while the LTC3649EFE is available in a 28-lead, thermally enhanced TSSOP package. The industrial grade versions LTC3649IUFD and LTC3649IFE operate over a -40C to 125C operating junction temperature range.
