Low-loss Step-down Regulator

September 1, 2014 | 23:12
Low-loss Step-down Regulator
Low-loss Step-down Regulator

Adding to their ever growing family of power supply regulators Linear Technology have introduced the LTC3807 step-down switching regulator DC/DC controller driving an all N-channel external synchronous power MOSFET stage. The chip uses a constant frequency current mode architecture allowing a phase-lockable frequency of up to 750 kHz.

The chip draws just 50 μA no-load quiescent current and an OPTI-LOOP compensation allows the transient response to be optimized over a wide range of output capacitance and ESR values. The LTC3807 features a precision 0.8 V reference and power-good output indicator.

The TRACK/SS pin ramps the output voltages during start-up. Current foldback limits the MOSFET heat dissipation during short-circuit conditions. The PLLIN/MODE pin selects either burst-mode operation, pulse-skipping or continuous conduction mode at light loads.

LTC3807 main features:

  • Wide VIN range: 4 V to 38 V (40V abs max)
  • Low operating IQ: 50 μA
  • Wide output voltage range: 0.8 V ≤ VOUT ≤ 24 V
  • RSENSE or DCR current sensing
  • Phase-lockable frequency (75 kHz to 750 kHz)
  • Programmable fixed frequency (50 kHz to 900 kHz)
  • Selectable continuous, pulse-skipping or low ripple burst mode operation at light load
  • Selectable current limit
  • Very low dropout operation: 99% duty cycle
  • Adjustable output voltage soft-start or tracking
  • Power good output voltage monitor
  • Output overvoltage protection
  • Low shutdown IQ: 14 μA
  • Internal LDO powers gate drive from VIN or EXTVCC
  • No current foldback during start-up

The LTC 3807 is available in 20-pin 3 × 4 mm QFN and TSSOP packages

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