Product Details

The EVAL-LT8306-AZ evaluation circuit is a micro-powered no-opto isolated flyback converter that features the LT8306. This demo circuit outputs 12V and maintains tight regulation with a load current from 15mA to 2.0A and over an input voltage from 6V to 36V. The output current capability increases with the input voltage.

The EVAL-LT8306-AZ needs very small minimum load (15mA) to regulate the output voltage because of the LT8306 ultra-low switching frequency at very light load. To properly limit the output voltage and avoid preloading under a no-load condition, a 13V zener diode is placed between the VOUT+ and VOUT- pins.

Transformer leakage inductance causes a voltage spike on the primary side after the power switch turns off. To limit this leakage inductance spike within a MOSFET voltage rating of 120V, an RC snubber and a TVS clamp are installed to dampen the ringing and clamp the MOSFET drain voltage to a safe level. The RC snubber can be removed to improve the efficiency by 3–4% when the load is below 100mA at 24V typical input.

The Performance Summary table in the user guide summarizes the performance of the evaluation circuit at room temperature. The evaluation circuit can be easily modified for different applications with some predesigned transformers.

The LT8306 is a simple-to-use micropowered isolated flyback controller. By sampling the isolated output voltage directly from the primary-side flyback waveform, the IC does not require a third winding or an opto-isolator for regulation. The IC sets the isolated output voltage with a single external resistor. It integrates loop compensation and an internal soft-start circuit to reduce external components. Boundary mode operation provides a small magnetic solution with excellent load regulation. The low-ripple burst mode operation maintains high efficiency at light load while minimizing the output voltage ripple.

The LT8306 is packaged in a 6-lead ThinSOT. It is AEC-Q100 qualified for automotive applications. The LT8306 data sheet gives a complete part description, operation, and applications information. Refer to the data sheet in conjunction with the EVAL-LT8306-AZ evaluation circuit quick start guide.

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