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reference designLTC3859A

Analog Devices LTC3859A

Low IQ, Triple Output, Buck/Buck/Boost Synchronous Controller with Improved Burst Mode Operation

Overview

TopologySEPIC Buck-Boost Topology
Input voltage5.8-34 V
Switching frequency50-900 kHz
Output 11.2 V / 3 A

Description

The LTC®3859A is a high performance triple output (buck/ buck/boost) synchronous DC/DC switching regulator controller that drives all N-channel power MOSFET stages. Constant frequency current mode architecture allowsa phase-lockable switching frequency of up to 850kHz. The LTC3859A operates from a wide 4.5V to 38V input supply range. When biased from the output of the boost converter or another auxiliary supply, the LTC3859A canoperate from an input supply as low as 2.5V after start-up.The 55μA no-load quiescent current extends operating runtime in battery powered systems. OPTI-LOOP compensation allows the transient response to be optimized over a wide range of output capacitance and ESR values.The LTC3859A features a precision 0.8V reference for the bucks, 1.2V reference for the boost and a power good output indicator. The PLLIN/MODE pin selects among Burst Mode operation, pulse-skipping mode, or continuous inductor current mode at light loads.Compared to the LTC3859, the LTC3859A's boost controller has improved performance in Burst Mode operation when the input voltage is higher than the regulated output voltage.

Features

  • Dual Buck Plus Single Boost Synchronous Controllers
  • Outputs Remain in Regulation Through Cold Crank Down to 2.5V
  • Low Operating IQ: 55μA (One Channel On)
  • Wide Bias Input Voltage Range: 4.5V to 38V
  • Buck Output Voltage Range: 0.8V ≤ VOUT ≤ 24V
  • Boost Output Voltage Up to 60V
  • RSENSE or DCR Current Sensing
  • 100% Duty Cycle for Boost Synchronous MOSFET
  • Even in Burst Mode® Operation
  • Phase-Lockable Frequency (75kHz to 850kHz)
  • Programmable Fixed Frequency (50kHz to 900kHz)
  • Selectable Continuous, Pulse-Skipping or Low Ripple
  • Burst Mode Operation at Light Loads
  • Very Low Buck Dropout Operation: 99% Duty Cycle
  • Adjustable Output Voltage Soft-Start or Tracking
  • Low Shutdown IQ: 14μA
  • Small 38-Pin 5mm × 7mm QFN and TSSOP Packages

Typical applications

  • Battery Operated Digital Devices
  • Distributed DC Power Systems
  • Multioutput Buck-Boost Applications
  • Automotive Always-On and Start-Stop Systems

More information

Products

Order Code Data­sheet Simu­lation Downloads Status Product seriesL
(µH)		IRP,40K
(A)		ISAT,10%
(A)		ISAT,30%
(A)		RDC
(mΩ)		fres
(MHz)		Material Samples
744311220SPEC

PCN pending

Due to a pending PCN there will be a new datasheet revision issued for this order code soon. Please find the actual as well based on valid PCN date the new revision datasheet below. If you have further questions please get in contact with our sales staff.

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 Active i| Production is active. Expected lifetime: >10 years.WE-HCI SMT Flat Wire High Current Inductor 2.2 10.2 5.6 13 11.4 52 Superflux
Order Code Data­sheet Simu­lation
744311220SPEC

PCN pending

Due to a pending PCN there will be a new datasheet revision issued for this order code soon. Please find the actual as well based on valid PCN date the new revision datasheet below. If you have further questions please get in contact with our sales staff.

Samples
Order Code Data­sheet Simu­lation Downloads Status Product seriesL
(µH)		IRP,40K
(A)		ISAT,10%
(A)		ISAT,30%
(A)		RDC
(mΩ)		fres
(MHz)		Material Samples