Notification 110 - Optimization failed: Duty cycle (DMAX) is above the maximum limit

CATEGORY

ISSUE / RESULT

FIX / REFERENCE(S)

Failure

The solution required abnormally low reflected voltage (VOR) to reduce duty cycle (DMAX) to within operating guidelines.

If duty-cycle guidelines are not met, the power supply may not deliver full rated output power, under the worst-case conditions of low line and full load, at maximum ambient temperature.

• If the design is intended to operate in the discontinuous conduction mode, increase the current waveform parameter (KP).

• Increase the input capacitance (CIN), which will increase the minimum input voltage (VMIN).

• Reduce the DRAIN-SOURCE voltage (VDS), which may require a larger device

• In cases where low input voltage (VACMIN, VDCMIN) is required and the optimization has failed, reduce the VOR and complete the design manually.  Note: this may require increasing the number of secondary turns (NS).

• See Application Notes AN-26 (-FX )  or AN-32 (-GX)  for details on how maximum duty cycle (DMAX) is calculated.