Components

150V Step-Down DC-DC Controller Draws 9µA IQ

Analog Devices announced the Power by Linear™ LTC3894, a high-voltage step-down dc-dc controller that draws only 9µA quiescent current with the output enabled in Burst Mode® operation. Its wide 4.5V to 150V input voltage range can effectively eliminate the need for external surge suppression devices.

The LTC3894's 100% duty cycle capability and externally adjustable power good window are ideal for use in battery powered systems that operate continuously in dropout. The LTC3894 is well-suited for transportation systems, always-on power, industrial control, robotic and datacom applications.

LTC3894The LTC3894 drives a P-channel MOSFET power stage and can produce an output voltage from 0.8V to 60V at output currents up to 3A with efficiencies as high as 92%. The LTC3894 includes the option for an external N-channel pass FET to supply the PMOS gate driver current in sustained high-voltage high-power applications.

The LTC3894 operates with a selectable fixed frequency between 50kHz and 850kHz and is synchronizable to an external clock from 75kHz to 800kHz. The user can select between pulse-skipping or Burst Mode operation during light loads. Its current mode architecture provides easy loop compensation, fast transient response and excellent line regulation.

Current sensing is accomplished by measuring the voltage drop across the output inductor (DCR) for highest efficiency or by using an optional sense resistor. A low 100ns minimum on-time allows for high step-down ratios at high switching frequency.

Current foldback limits MOSFET heat dissipation during overload conditions. Additional protection features include, a power good output signal, adjustable input overvoltage lockout and soft-start.

The LTC3894 is available in a 16-pin thermally enhanced TSSOP with high voltage pin spacing. Extended and industrial versions are available from -40°C to 125°C.  In lots of 1,000 pieces, pricing starts at $2.55.

Summary of features:

  • Wide Input Voltage Range: 4.5V to 150V
  • Wide VOUT Range: 0.8V to 60V
  • Low 9µA Burst Mode® VIN Quiescent Current, when Regulating from 48V to 3.3V
  • RSENSE or Inductor DCR Current Sensing
  • Programmable Power Good Undervoltage Monitor
  • Internal Fixed Soft-Start or Externally Programmable Soft-Start or Voltage Tracking
  • Selectable Fixed Operating Frequency from 50kHz to 850kHz
  • PLL Synchronizable Operating Frequency from 75kHz to 800kHzB8
  • Current Mode Control for Fast Transient Response & Easy Loop Compensation
  • Adjustable Soft-Start or Tracking
  • Output Overvoltage & Overcurrent Protection
  • Power Good Output Signal
  • Optional External NMOS for Gate Driver Bias Current
Analog Devices Inc.
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