60V, 4A Synchronous StepDown Regulator with Adjustable Rail-to-Rail Output & Wire Drop Compensation

The Linear Technology's LTC3649 is a high efficiency, 60 V, 4 A synchronous buck regulator that incorporates a constant frequency, current mode architecture and programmable output current and output voltage, which are set with a single external resistor. The LTC3649 operates from an input voltage range of 3.1 V to 60 V and provides an adjustable rail-to-rail output voltage range from 0 V to 0.5 V below V_IN, while delivering up to 4 A of continuous output current. Its wide input and output voltage range is ideal for a wide range of test, measurement and industrial applications. The LTC3649’s unique design includes an accurate internally generated 50 μA current source on the I_SET pin, enabling it to deliver outputs as low as 0 V with the use of a single external programming resistor. Furthermore, the LTC3649 offers ±0.8% output voltage accuracy and programmable output current with ±4% accuracy without a sense resistor. Its switching frequency is user programmable from 300 kHz to 3 MHz, enabling the use of tiny, low cost capacitors and inductors. Combined with a 28-lead 4 mm × 5 mm QFN or thermally enhanced TSSOP package, the LTC3649 offers a very compact solution footprint.

The LTC3649 uses internal power switches with R_DS(ON) of only 100 mOhms and 50 mOhms to deliver efficiencies as high as 95%. Burst Mode operation offers high efficiency at light loads, requiring only 440 μA of quiescent current. For noise sensitive applications, the LTC3649 can run in forced continuous mode, offering very low output ripple. Additional features include ±4% accurate output current monitoring, a power good voltage monitor, programmable wire drop compensation, external synchronization capability and thermal protection.

The LTC3649EUFD is available in a 4 mm × 5 mm QFN-28, the LTC3649EFE is offered in a 28-lead, thermally enhanced TSSOP package. Industrial grade versions, the LTC3649IUFD and LTC3649IFE, are guaranteed to operate over the –40 °C to 125 °C operating junction temperature range. Pricing starts at $5.65 each in 1,000-piece quantities. All versions are available from stock.

Summary of Features: LTC3649

• Wide V_IN Range: 3.1 V to 60 V
• Wide V_OUT Range: 0 V to (V_IN – 0.5 V)
• Single Resistor V_OUT Programming
• Integrated 110 mΩ Top N-Channel/ 50 mΩ Bottom N-Channel MOSFETs
• 95% Efficiency with 12 V_IN and 5 V_OUT
• Active I_Q: 440 μA, Shutdown IQ: 15 μA
• Accurate Current Monitoring (±4%) without Sense Resistor
• Accurate Resistor Programmable Frequency (300 kHz to 3 MHz) with ±50% Frequency Sync Range
• Accurate Programmable Output Current Limit
• Input Voltage Regulation for MPPT Applications
• ±0.8% Output Voltage Accuracy
• Peak Current Mode Operation
• Programmable Wire Drop Compensation
• Burst Mode Operation, Forced Continuous Mode
• Internal Compensation & Programmable SoftStart
• Overtemperature Protection
• Available in Thermally Enhanced 28-Lead 4 mm × 5 mm QFN & TSSOP Packages