AN4165 datasheet(17/37 Pages) STMICROELECTRONICS

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AN4165

Efficiency

Doc ID 023661 Rev 1

17/37

Efficiency

Active mode efficiency is defined as the average of the efficiencies measured at 25%, 50%,

75% and 100% of maximum load, at nominal input voltage (VIN = 115 VAC and

VIN =230 VAC).

External power supplies (the power supplies which are housed separately from the end-use

devices they are powering) need to comply with the Code of Conduct (version 4.0) "Active

mode efficiency" criterion, which requires an active mode efficiency higher than 77.7% for a

power throughput of 12 W.

Another standard to be applied to external power supplies in the coming years is the DOE

(Department of Energy) recommendation, whose active mode efficiency requirement for the

same power throughput is 82.96%.

The average efficiencies of the board at 115 VAC (83.33%) and at 230 VAC (81.34%) are

represented by dotted lines, and, along with the above limits, show that the STEVAL-

ISA111V1 demonstration board is compliant with both standards at 115 VAC and with the

Code of Conduct only at 230 VAC (refer to Figure 20 below).

In the same figure the efficiency at 25%, 50%, 75% and 100% of maximum load for both

input voltages is also shown.

Figure 20.

Active mode efficiency of the demonstration board in comparison to

energy efficiency standards

AM13375v1

0.2

0.4

0.6

0.8

Iout [% I

OUT ]

115

230

av @ 115Vac

av @ 230Vac

DOE limit

CoC4 limit

AN4165 Datasheet(PDF) 17 Page - STMicroelectronics