AN4116 datasheet(16/38 Pages) STMICROELECTRONICS

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Testing the board

AN4116

16/38

Doc ID 023220 Rev 1

Table 5 shows the measured value of the burst mode frequency ripple measured in different

operating conditions. The ripple in burst mode operation is very low.

5.4

Efficiency

The 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 contained in a separate housing

from the end-use devices they are powering) need to comply with the Code of Conduct

(version 4) “Active Mode Efficiency” criterion, which states an active mode efficiency higher

than 71.18% for a power throughput of 4.2 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 76.6%.

If the IC is externally biased, the presented demonstration board is compliant with both

standards, as can be seen from

Figure 21, where the average efficiencies of the board at

115 VAC (81.6%) and at 230 VAC (77.2%) are plotted with dotted lines, together with the

above limits. In the same figure the efficiency at 25%, 50%, 75% and 100% of output load

for both input voltages is also shown.

Figure 19.

Output voltage ripple @ 115 VAC

25 mA

Figure 20.

Output voltage ripple @ 230 VAC

25 mA

AM11694v1

AM11695v1

Table 5.

Output voltage ripple at no/light load

VIN [VAC]

VOUT [mV]

No load

25 mA load

115

230

265

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