1N4004 Просмотр технического описания (PDF) - STMicroelectronics
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1N4004 Datasheet PDF : 42 Pages
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AN1262 APPLICATION NOTE
experience in converters with opto-isolated feedback. This variation is a result of the poor magnetic cou-
pling with the secondary winding. It is then recommended to design the turns ratio of the self-supply
winding so as to get a voltage approximately in the middle of this range (e.g. 11-12 V). This will give
allowance for increasing at heavy load and dropping at zero load.
s Secondary diode forward drop. The type of secondary diode will be selected basically depending on the
output voltage. In fact this determines the maximum reverse voltage applied to the diode while the MOS-
FET is switched on. For low output voltages ≤15 V) a Schottky diode can be used and a typical forward
drop of 0.5V can be considered; for higher output voltages an ultrafast PN diode will be used, with a
typical forward drop of 0.8 V.
s Bridge Rectifier + EMI filter voltage drop. This drop is subtracted to the peak of the input AC voltage and
affects the peak voltage of the ripple superimposed on top of the DC voltage across the input bulk ca-
pacitor. A typical value can be 3 V.
4 PRELIMINARY CALCULATIONS (STEP 1)
There are a few quantities that need to be calculated before starting the individual design of each functional
block of the converter. They are summarized in table 3.
Table 3. Preliminary calculations (step 1).
Symbol
Parameter
Pin
Converter Input Power
Iout
DC Output Current
VPKmin
VPKmax
Minimum Peak Input Voltage
Maximum Peak Input Voltage
Definition
Pin = P-----o---u-η--t--m----a---x
Io ut = P----o-V--u---ot--m-u---ta---x--
VPKmin = VACmin · 2 – VBF
VPKmax = VACmax ⋅ 2
5 BRIDGE RECTIFIER SELECTION
Due to the limited power range that the device is able to handle, no special considerations are needed to select the
diodes of the bridge rectifier. Any 1A rated standard diodes with 400/600 V reverse voltage are suitable. Some man-
ufacturers make integrated bridge rectifiers housed in small packages. See table 4 for some suggested parts.
Table 4. 1A standard silicon rectifier and bridge selection
Type
Part Number
Rated Voltage
Package
Diode
1N4004
400
DO41
Diode
1N4005
600
DO41
Bridge
DF04M
400
DIL4
Bridge
DF06M
600
DIL4
Bridge
KBP104G
400
SIL4
Bridge
KBP105G
600
SIL4
Bridge
DFS04M
400
DIL4 (SMD)
Bridge
DFS06M
600
DIL4 (SMD)
Manufacturer(s)
GI, GS, FAGOR, HTA, ON, TSC
GI, GS, FAGOR, HTA, ON, TSC
GI,TSC
GI,TSC
TSC
TSC
HTA
HTA
5/42
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