42VIN Micropower No-Opto Isolated Flyback Converter with 65V/1.2A Switch
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Evaluation Kit ManualsDC2821A Demo Manual
Features and Benefits
- 2.8V to 42V Input Voltage Range
- 3.6A, 65V Internal DMOS Power Switch
- Low Quiescent Current:
- 106μA in Sleep Mode
- 380μA in Active Mode
- Quasi-Resonant Boundary Mode Operation at Heavy Load
- Low Ripple Burst Mode® Operation at Light Load
- Minimum Load < 0.5% (Typ) of Full Output
- No Transformer Third Winding or Opto-Isolator Required for Output Voltage Regulation
- Accurate EN/UVLO Threshold and Hysteresis
- Internal Compensation and Soft-Start
- Temperature Compensation for Output Diode
- Output Short-Circuit Protection
- Thermally Enhanced 8-Lead SO Package
The LT8302 is a monolithic micropower isolated flyback converter. By sampling the isolated output voltage directly from the primary-side flyback waveform, the part requires no third winding or opto-isolator for regulation. The output voltage is programmed with two external resistors and a third optional temperature compensation resistor. Boundary mode operation provides a small magnetic solution with excellent load regulation. Low ripple Burst Mode operation maintains high efficiency at light load while minimizing the output voltage ripple. A 3.6A, 65V DMOS power switch is integrated along with all the high voltage circuitry and control logic into a thermally enhanced 8-lead SO package.
The LT8302 operates from an input voltage range of 2.8V to 42V and delivers up to 18W of isolated output power. The high level of integration and the use of boundary and low ripple burst modes result in a simple to use, low component count, and high efficiency application solution for isolated power delivery.
- Isolated Automotive, Industrial, Medical Power Supplies
- Isolated Auxiliary/Housekeeping Power Supplies
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 2821A is a compact no-opto isolated flyback converter featuring the LT8302. The DC2821A outputs 12V, and maintains ±1% (typ) regulation with a load current from 5mA up to 1.4A and over an input voltage from 4V to 28V. The output current capability increases with the input voltage.
Transformer leakage inductance causes a voltage spike on the primary side after the power switch turns off. To limit this leakage inductance spike within the MOSFET voltage rating of 65V, an RC snubber and a TVS clamp are installed to damp the ringing and clamp the MOSFET drain voltage to a safe level.
The demo circuit can be easily modified for different applications using predesigned transformers.
The LT8302 data sheet gives a complete description of the part, operation and application information. The data sheet must be read in conjunction with the quick start guide for DC2821A.
Demonstration circuit 2014A is a micropower No-Opto isolated flyback converter featuring the LT8302. This demo circuit outputs 5V, and maintains tight regulation with a load current from 10mA to 2.2A over an input voltage from 10V to 30V. The output current capability increases with the input voltage.
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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