A6986ITR datasheet(19/62 Pages) STMICROELECTRONICS

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5.8

Output voltage load regulation

Primary output load regulation

Figure 18 shows negligible primary output voltage variation (normalized to the value measured at IOUT = 0 A) over

the entire output current range for the A6986I with VOUT = 5.3 V.

Figure 19. Load regulation of the non isolated output

-0.6%

-0.5%

-0.4%

-0.3%

-0.2%

-0.1%

0.0%

0.1%

0.2%

0.3%

0.4%

0.5%

0.6%

0.2

0.4

0.6

0.8

1.2

1.4

1.6

1.8

IOUT_prim [A]

Secondary output load regulation

Since there is not a regulation loop involving the secondary output, its load regulation depends to some extent

on the primary load regulation and is affected by the leakage inductance (see Figure 19) of the transformer,

the voltage drops across to the Schottky diode (diode forward voltage) and the DCR of the secondary coil, as

indicated by equation (1) (where only the last two contributions are considered). Minimizing all the mentioned

parameters leads to a better load regulation.

Figure 20. Effect of the transformer leakage inductance on the isolated output load regulation

-15%

-10%

-5%

10%

15%

100

IOUT [mA]

Lleak = 240nH

Lleak = 700nH

A6986I

Output voltage load regulation

DS13481 - Rev 2

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