LTC3803

PRODUCTION

Constant Frequency Current Mode Flyback DC/DC Controller in ThinSOT

Data Sheet Product Selection Table
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Overview

  • VIN and VOUT Limited Only by External Components
  • Adjustable Slope Compensation
  • Internal Soft-Start
  • Constant Frequency 200kHz Operation
  • ±1.5% Reference Accuracy
  • Current Mode Operation for Excellent Line and Load Transient Response
  • No Minimum Load Requirement
  • Low Quiescent Current: 240μA
  • Low Profile (1mm) SOT-23 Package

The LTC3803 is a constant frequency current mode flyback controller optimized for driving N-channel MOSFETs in high input voltage applications. Constant frequency operation is maintained down to very light loads, resulting in less low frequency noise generation over a wide range of load currents. Slope compensation can be programmed with an external resistor.

The LTC3803 provides ±1.5% output voltage accuracy and consumes only 240μA of quiescent current. Ground-referenced current sensing allows LTC3803-based converters to accept input supplies beyond the LTC3803’s absolute maximum VCC. A micropower hysteretic start-up feature allows efficient operation at high input voltages. For simplicity, the LTC3803 can also be powered from a high VIN through a resistor, due to its internal shunt regulator. An internal undervoltage lockout shuts down the LTC3803 when the input voltage is too low to provide sufficient gate drive to the external MOSFET.

The LTC3803 is available in a low profile (1mm) 6-lead SOT-23 (ThinSOT™) package.

Turn On Voltage Frequency
LTC3803 8.7V 200kHz
LTC3803-3 8.7V 300kHz
LTC3803-5 4.8V 200kHz

Applications

  • Telecom Power Supplies
  • 42V and 12V Automotive Power Supplies
  • Auxiliary/Housekeeping Power Supplies
  • Power Over Ethernet
LTC3803
Constant Frequency Current Mode Flyback DC/DC Controller in ThinSOT
5V Output Nonisolated Telecom Housekeeping Power Supply Efficiency vs Load Current Product Package 1
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Documentation

Data Sheet 1

Reliability Data 1

User Guide 2

Technical Articles 2

Data Sheet

This is the most up-to-date revision of the Data Sheet.

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Software Resources

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Hardware Ecosystem

Parts Product Life Cycle Description
Switching Regulators & Controllers 2
LTM8047
RECOMMENDED FOR NEW DESIGNS 3.1VIN to 32VIN Isolated μModule (Power Module) DC/DC Converter
LTM8048
RECOMMENDED FOR NEW DESIGNS 3.1VIN to 32VIN Isolated μModule (Power Module) DC/DC Converter with LDO Post Regulator
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Tools & Simulations

LTspice 2

Models for the following parts are available in LTspice:

  • LTC3803
  • LTC3803-3
  • LTC3803-5
LTspice

LTspice® is a powerful, fast and free simulation software, schematic capture and waveform viewer with enhancements and models for improving the simulation of analog circuits.

Evaluation Kits

eval board
schematic 1
DC649A

LTC3803ES6 Isolated Demo Board | Flyback Controller, 36V ≤ VIN ≤ 72V, VOUT = 5V@2A

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Product Details

Demonstration circuit 649 is a Telecom isolated DC/DC converter featuring the LTC3803 constant frequency current mode flyback controller. The DC649 converts an isolated 36V to 72V input and provides 2A of output current at 5V. The 200kHz constant frequency operation is maintained down to very light load to reduce low frequency noise generated over a wide range of load current. The converter provides high output voltage accuracy (typically ±2%) over wide load range with no minimum load requirement.

eval board
schematic 2
DC781A

LTC3803ES6 Demo Board | Synchronous Flyback, 36V ≤ VIN ≤ 72V, VOUT = 3.3V/5V @ 2A

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Product Details

Demonstration circuit 781 is a Telecom DC/DC converter featuring the LTC3803ES6 constant frequency current mode flyback controller. The DC781 converts 36V to 72V input to 3.3V or 5V output and provides 2A of output current. The 200kHz constant frequency operation is maintained down to zero load which prevents low frequency noise that occurs when power converters operate in pulse skipping mode. The converter provides high output voltage accuracy (typically ±2%) over wide load range with no minimum load requirement.
DC649A
LTC3803ES6 Isolated Demo Board | Flyback Controller, 36V ≤ VIN ≤ 72V, VOUT = 5V@2A
DC649A - Schematic
DC781A
LTC3803ES6 Demo Board | Synchronous Flyback, 36V ≤ VIN ≤ 72V, VOUT = 3.3V/5V @ 2A
DC781A - Schematic

Latest Discussions

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isolated DC/DC recommendation
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