AN1537 APPLICATION NOTE

8/18

Figure 11. 45W AC-DC adapter: load transient 0.1

⇔ 2.5A @ 220Vac

Optimization of a 80W AC-DC adapter with PFC

Table 4 summarizes the items of the electrical spec of this adapter more relevant to this context. Please refer

to [4] for full electrical spec and evaluation data, as well as for a detailed description.

Table 4. 80W AC-DC adapter with PFC: electrical specification of the original design

The full-load input power is greater than 100W, then this adapter is actually out of the scope of the ECC. Its no

load consumption (0.9W @265Vac, 0.7W @220 Vac), however, is within the Phase 1 limit (1W) and not far

from that of Phase 2 and 3 (0.75W @230 Vac) for the highest power bracket.

Again, the target of the optimization is to meet Phase 3 limit @Vin = 264 Vac. Figure 12 shows the electrical

schematic with the added and modified components highlighted. Only these changes, which track those made

in the previously considered design plus those related to the PFC stage, will be discussed

90 to 265Vac

50/60Hz

80W

Output

Line and Load regulation

< 1%

65kHz

20kHz

η > 75%

< 1W

Iout

Vout

COMP (pin 6 of L5991)