EPR-000013 Datasheet, PDF (40/56 Pages) Power Integrations, Inc. – Engineering Prototype Report (EP13) 43 W / 57 W pk, 5 Output TOPSwitch팜-GX (TOP246Y) Power Supply

EPR-000013 – 43 W Multiple Output TOP246 Power Supply
08-May-2001
15.3 EP13 115 V_AC Version Circuit Description
The circuit shown in the schematic of Figure 38 is a 115 VAC-only version of the EP13.
Several notable changes were made in the circuit to accommodate 115 VAC-only
operation. C2 is changed from 68 µF, 400 V to 150 µF, 200 V. RT1, D1-4, and L1 were
changed to devices with higher current rating to accommodate the increased current
draw at 115 VAC. U1 is changed from a TOP246Y to a TOP247Y, which has a higher
current rating.
Since the 115 VAC-only supply runs at a higher primary peak and RMS current, the
secondary RMS currents are correspondingly higher. To handle the increased secondary
RMS ripple current, the filter capacitors in the 5 V and 3.3 V outputs (C13-14 and C16-
17) are changed to devices with a higher ripple current rating.
R12 and C21 have been added on the secondary voltage control to inject AC ripple
information from the 12 V output into the control circuit. This “ripple steering” circuit
reduces the 12 V output ripple, especially at low AC input voltage.
T1 is replaced with a conventional margin-wound ERL28 transformer, since the multiple
section transformer used in the 230 VAC version of the EP13 cannot handle the higher
primary and secondary currents present at lower input voltages. The 5 V and 3.3 V
secondaries in this transformer are wound using copper foil to reduce resistive losses
and improve cross regulation.
Power Integrations, Inc.
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