Features and Benefits
- 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|
- Telecom Power Supplies
- 42V and 12V Automotive Power Supplies
- Auxiliary/Housekeeping Power Supplies
- Power Over Ethernet
Product Lifecycle Production
At least one model within this product family is in production and available for purchase. The product is appropriate for new designs but newer alternatives may exist.
Evaluation Kits (2)
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.
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.
Tools & Simulations
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.
To launch ready-to-run LTspice demonstration circuits for this part:
Step 1: Download and install LTspice on your computer.
Step 2: Click on the link in the section below to download a demonstration circuit.
Step 3: If LTspice does not automatically open after clicking the link below, 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.
Models for the following parts are available in LTspice:
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Sample & Buy
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 Analog Devices, Inc. sales office or authorized distributor. Pricing displayed for Evaluation Boards and Kits is based on 1-piece pricing.