LTC3851 Wide Input Voltage Range Synchronous Step-Down DC/DC Controller

Wide Input Voltage Range Synchronous Step-Down DC/DC Controller

Image of Linear Technology's LTC3851Linear Technology Corporation announces the LTC3851, a wide input range synchronous step-down switching regulator controller that drives all N-channel power MOSFET stages and has coincident or ratiometric tracking. The 4V to 38V input range encompasses a wide variety of applications, including most intermediate bus voltages and battery chemistries. The strong on-board MOSFET gate drivers allow the use of high power external MOSFETs to produce output currents up to 20A with output voltages ranging from 0.8V to 5.5V, making the LTC3851 ideal for point-of-load requirements. Applications include automotive, industrial, medical, datacom and telecom systems, multifunction printers and set-top boxes.

A constant-frequency current mode architecture provides a selectable fixed or phase-lockable (PLL) frequency from 250kHz to 750kHz . OPTI-LOOP® compensation allows the transient response to be optimized over a wide range of output capacitance and ESR values, including all ceramic capacitors designs. Output current sensing is accomplished by measuring the voltage drop across the output inductor (DCR) or by using an optional sense resistor; also the current limit threshold voltage is programmable. Current foldback limits MOSFET heat dissipation during short-circuit and over-load conditions. In addition, the LTC3851 has adjustable soft-start to control the turn-on time and manage inrush current. Selectable Burst Mode® operation, pulse skip mode or continuous current mode is user controlled to optimize light load efficiency vs. output ripple. The LTC3851 features a precision 0.8V reference with an accuracy of ±1% over a -40°C to 85°C operating temperature range. With up to 99% duty cycle, the LTC3851 has a very low drop-out voltage, a useful feature for extending run times in battery powered applications.

  • VIN Range: 4V to 38V
  • Strong On-Board N-Channel MOSFET Driver
  • Tracking
  • Programmable Current Limit Threshold Voltage
  • Programmable Soft-Start
  • 250kHz to 750kHz
  • VOUT Range: 0.8V to 5.5V
  • Current Mode Control
  • DCR or RSENSE Current Sense Options
  • Phase-Lock-Loop Synchronization
  • Fixed Operating Frequency or Synchronizable from
  • ±1% Reference Voltage Accuracy over -40°C to +85°C


ImageManufacturer Part NumberDescriptionOutput TypeAvailable Quantity
LTC3851EUD#PBF datasheet linkIC REG CTRLR BUCK 16QFNLTC3851EUD#PBFIC REG CTRLR BUCK 16QFNTransistor Driver282 - Immediate
LTC3851EUD#PBF product page link
LTC3851EMSE-1#PBF datasheet linkIC REG CTRLR BUCK 16MSOPLTC3851EMSE-1#PBFIC REG CTRLR BUCK 16MSOPTransistor Driver301 - Immediate
LTC3851EMSE-1#PBF product page link
LTC3851EGN#PBF datasheet linkIC REG CTRLR BUCK 16SSOPLTC3851EGN#PBFIC REG CTRLR BUCK 16SSOPTransistor Driver168 - Immediate
LTC3851EGN#PBF product page link
LTC3851AEMSE#PBF datasheet linkIC REG CTRLR BUCK 16MSOPLTC3851AEMSE#PBFIC REG CTRLR BUCK 16MSOPTransistor Driver140 - Immediate
LTC3851AEMSE#PBF product page link
LTC3851AEGN#PBF datasheet linkIC REG CTRLR BUCK 16SSOPLTC3851AEGN#PBFIC REG CTRLR BUCK 16SSOPTransistor Driver199 - Immediate
LTC3851AEGN#PBF product page link
LTC3851IUD#PBF datasheet linkIC REG CTRLR BUCK 16QFNLTC3851IUD#PBFIC REG CTRLR BUCK 16QFNTransistor Driver423 - Immediate
LTC3851IUD#PBF product page link
LTC3851EMSE#PBF datasheet linkIC REG CTRLR BUCK 16MSOPLTC3851EMSE#PBFIC REG CTRLR BUCK 16MSOPTransistor Driver58 - Immediate
LTC3851EMSE#PBF product page link
LTC3851EUD-1#PBF datasheet linkIC REG CTRLR BUCK 16QFNLTC3851EUD-1#PBFIC REG CTRLR BUCK 16QFNTransistor Driver92 - Immediate
LTC3851EUD-1#PBF product page link
Published: 2013-10-11