Notification 216 - Gap Length (LG) is smaller than the practical limit

CATEGORY

ISSUE / RESULT

FIX / REFERENCE(S)

Info

The required transformer gap length (LG) is smaller than the practical design limit of 0.10 mm.

The transformer may not meet manufacturability standards and widely varying component characteristics and tolerances (such as LP) may result.

• Increase the size and the cross-sectional area (AE) of the core.  This increases its effective un-gapped inductance (AL).

• Increase the number of both the primary (NP) and the secondary turns (NS).

• Increase the current waveform parameter ( KP), which will decrease the primary winding inductance (LP).

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

• Decrease the power supply’s output power requirement (PO), which will reduce the primary winding inductance (LP).

• See Application Notes AN-43 (-HX) and AN-47  (-JX)> for details on how gap length (LG) is calculated.