1N4004 データシートの表示（PDF） - STMicroelectronics

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1N4004

OFFLINE FLYBACK CONVERTERS DESIGN METHODOLOGY WITH THE L6590 FAMILY

STMicroelectronics 

AN1262 APPLICATION NOTE

11 SECONDARY RECTIFIER SELECTION

Although the converter is operated in DCM, it is recommended to use an ultrafast p-n diode or, whenever al-

lowed by the reverse voltage, a Schottky type. The latter, besides optimizing the reverse recovery, minimizes

conduction losses as well.

The voltage rating will be higher than the maximum reverse voltage it experiences:

VREV = Vo ut ⋅ 1 + -V----P--V-K---R-m----a---x- ,

(17)

with a suitable safety margin (usually 20-25%). As to its current rating, it is a common design practice to choose

a diode rated for 2-3 times the DC output current Iout. Table 14 lists some recommended devices available from

ST assuming VR = 130 V. In each cell of the table there are two recommended devices, the first one is an axial

or through-hole diode and the second one is in SMD package. The sale types in italic are p-n diodes, the others

are Schottky type.

Table 14. Recommended ST parts for secondary rectification.

110 VAC

220 VAC or WRM

Vout

(V)

Pout≤5W

Pout=7.5W

Pout=10W

Pout≤5W

Pout=7.5W

Pout=10W

3.3

1N5820

STPS5L25B-1 STPS10L25D

1N58210

STPS5L25B-1 STPS10L25D

STPS5L25B

STPS5L25B STPS10L25G STPS3L25S

STPS5L25B STPS10L25G

5

1N5820

1N5820

STPS10L25D

1N5821

STPS5L25B

STPS5L25B STPS10L25G

STPS340C

1N5822

STPS340B

STPS640CT

STPS640CB

9

1N5821

STPS2L30A

1N5821

STPS340B

1N5822

STPS340B

–

STPS160U

–

STPS3L60S

STPS5H100-1

STPS3L60S

12

1N5819

1N5822

–

–

–

STPS5H100B-1

STPS1L40A

STPS3L60S

STPS3L60S STPS1H100U STPS2H100U STPS2H100U

15

BYV10-60

STPS160A

BYV10-60

STPS160A

–

STPS3L60S

–

–

STPS5H100B-1

STPS1H100U STPS2H100U STPS2H100U

18

BYV10-60

BYV10-60

BYW98-100

–

–

STPS5H100B-1

STPS160A

STPS1H100U STPS2H100U STPS1H100U STPS2H100U STPS2H100U

24

BAT49

–

–

BYW100-200 BYW100-200 BYW100-200

STPS1H100A STPS1H100U STPS1H100U

STPR120A

STPR120A SMBYW02-200

12 OUTPUT CAPACITOR SELECTION AND POST FILTER

Large, low-ESR electrolytic capacitors usually do the filtering work. The parameters to be considered for their

selection are the working voltage, RMS ripple rating and ESR, the actual capacitance value is of secondary im-

portance.

Obviously, the DC working voltage must be greater than Vout. A margin of 25% is recommended for the sake of

reliability.

The AC current the output capacitor undergoes causes power dissipation on its ESR and a resulting tempera-

ture rise. This is the major responsible for capacitor degrading. Thus it is important not to operate the capacitor

beyond its AC current ripple rating, otherwise its lifetime will be considerably shortened. This parameter is usu-

ally specified at 85°C or 105°C ambient temperature, depending on capacitor's quality. The value could be de-

rated considering the actual maximum ambient temperature (Tamb) and the capacitor's target lifetime. For a

conservative design no derating will be applied. The AC current capability must then be larger than IsAC and

18/42

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