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LTC3850 - Dual, 2-Phase Synchronous Step-Down Switching Controller

Features

  • Dual, 180° Phased Controllers Reduce Required
  • Input Capacitance and Power Supply Induced Noise
  • High Efficiency: Up to 95%
  • RSENSE or DCR Current Sensing
  • ±1% 0.8V Output Voltage Accuracy
  • Phase-Lockable Fixed Frequency 250kHz to 780kHz
  • Supports Pre-Biased Output
  • Dual N-Channel MOSFET Synchronous Drive
  • Wide VIN Range: 4V to 24V (30V for LTC3850I) Operation
  • Adjustable Soft-Start Current Ramping or Tracking
  • Foldback Output Current Limiting
  • Output Overvoltage Protection
  • Power Good Output Voltage Monitor
  • 28-Pin 4mm × 4mm, 4mm × 5mm QFN and Narrow SSOP Packages

Typical Application

LTC3850 Typical Application
LTC3850 Typical Application

Description

The LTC3850 is a high performance dual synchronous step-down switching regulator controller that drives all N-channel power MOSFET stages. A constant-frequency current mode architecture allows a phase-lockable frequency of up to 780kHz. Power loss and supply noise are minimized by operating the two controller output stages out of phase.

OPTI-LOOP compensation allows the transient response to be optimized over a wide range of output capacitance and ESR values. The LTC3850 features a precision 0.8V reference and a power good output indicator. A wide 4V to 24V (28V maximum/30V for LTC3850I) input supply range encompasses most battery chemistries and intermediate bus voltages.

Independent TK/SS pins for each controller ramp the output voltages during start-up. Current foldback limits MOSFET heat dissipation during short-circuit conditions. The MODE/PLLIN pin selects among Burst Mode operation, pulse-skipping mode, or continuous inductor current mode and allows the IC to be synchronized to an external clock.

The LTC3850 is available in low profile 28-pin 4mm x 4mm, 4mm x 5mm QFN and narrow SSOP packages.

Packaging

For complete and up to date package information and drawings, please refer to our packaging page

SSOP-28, QFN-28

LTC3850 Package Drawing
LTC3850 Package Drawing
LTC3850 Package Drawing

Order Info

Package Variations and Pricing

Part Number Package Pins Temp Price (1-99) Price (1k)* RoHS Data
LTC3850EGN#PBF SSOP 28 E $3.43 $2.40 View
LTC3850EGN#TRPBF SSOP 28 E $2.46 View
LTC3850EGN-1#PBF SSOP 28 E $3.43 $2.40 View
LTC3850EGN-1#TRPBF SSOP 28 E $2.46 View
LTC3850EUF#PBF QFN 28 E $3.43 $2.40 View
LTC3850EUF#TRPBF QFN 28 E $2.46 View
LTC3850EUFD#PBF QFN 28 E $3.43 $2.40 View
LTC3850EUFD#TRPBF QFN 28 E $2.46 View
LTC3850IGN#PBF SSOP 28 I $3.64 $2.55 View
LTC3850IGN#TR SSOP 28 I $2.61 View
LTC3850IGN#TRPBF SSOP 28 I $2.61 View
LTC3850IGN-1#PBF SSOP 28 I $3.64 $2.55 View
LTC3850IGN-1#TRPBF SSOP 28 I $2.61 View
LTC3850IGN-2#PBF SSOP 28 I $3.64 $2.55 View
LTC3850IGN-2#TRPBF SSOP 28 I $2.61 View
LTC3850IUF#PBF QFN 28 I $3.64 $2.55 View
LTC3850IUF#TRPBF QFN 28 I $2.61 View
LTC3850IUFD#PBF QFN 28 I $3.64 $2.55 View
LTC3850IUFD#TRPBF QFN 28 I $2.61 View
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* The USA list pricing shown is for BUDGETARY USE ONLY, shown in United States dollars (FOB USA per unit for the stated volume), and is subject to change. International prices may differ due to local duties, taxes, fees and exchange rates. For volume-specific price or delivery quotes, please contact your local Linear Technology sales office or authorized distributor.

Demo Boards

Linear Technology demo boards are offered free of charge to qualified customers. Contact your local sales office or distributor to request a demo board. Certain demo boards are also available for sale via credit card on this website. Demo boards are for evaluation purposes only. It remains the customer’s responsibility to verify proper and reliable operation in the actual end application.

Part Number Description Price Documentation
DC1126A LTC3850EUF Demo Board | 6.5V < Vin < 14V, Vout 1=3.3V/5A, Vout 2=2.5V/5A $150.00
DC1185A-A LTC3850EUF Demo Board $150.00
DC1185B-A LTC3850EUF Demo Board Contact Factory
DC1185B-B LTC3850EUF Demo Board $150.00
DC1231A-A LTC3850EGN Demo Board | 6.5V < Vin < 24V, Vout 1=3.3V/5A, Vout 2=2.5V/5A $150.00
DC1231A-B LTC3850EGN Demo Board | 6.5V < Vin < 24V, Vout 1=3.3V/5A, Vout 2=2.5V/5A, with DCR Current Sense $150.00
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Click here to view our complete list of demo boards

Applications

  • Notebook and Palmtop Computers
  • Portable Instruments
  • Battery-Operated Digital Devices
  • DC Power Distribution Systems

Simulate

LTspice IV is a powerful, fast and free simulation tool, schematic capture and waveform viewer with enhancements and models for improving the simulation of switching regulators. To download LTspice IV and other FREE simulation tools, please visit our Design Simulation page.

To launch a ready to run LTspice demonstration circuit for this part:

  • Step 1: If you have not installed LTspice on this computer, download and install LTspice IV
  • Step 2: Once LTspice is installed, click on the link(s) below to launch the simulation
  • Step 3: If LTspice IV does not automatically open after clicking the link above, you can instead run the simulation by right clicking on the link and selecting "Save Target As". After saving the file to your computer, start LTspice and open the demonstration circuit by selecting 'Open' from the 'File' menu

To explore other ready to run LTspice demonstration circuits, please visit our Demo Circuits Collection.

Related models available in LTspice IV
LTC3850-1
LTC3850-2
LTC3850

Technical Support