STEVAL-ISA011V1 STMicroelectronics, STEVAL-ISA011V1 Datasheet - Page 8

• Manufacturer Part Number: STEVAL-ISA011V1
• Description: BOARD EVAL VIPER12A LP AC/DC
• Manufacturer: STMicroelectronics
• Series: VIPER™r
• Type: AC/DC Switching Convertersr

Specifications of STEVAL-ISA011V1

• Design Resources: STEVAL-ISA011V1 Gerber Files STEVAL-ISA011V1 Schematic STEVAL-ISA011V1 Bill of Materials
• Main Purpose: AC/DC, Primary Side
• Outputs And Type: 1, Isolated
• Power - Output: 4.1W
• Voltage - Output: 4.5V
• Current - Output: 900mA
• Voltage - Input: 88 ~ 265VAC
• Regulator Topology: Flyback
• Frequency - Switching: 60kHz
• Board Type: Fully Populated
• Utilized Ic / Part: VIPer12A
• Input Voltage: 88 V to 265 V
• Output Voltage: 4.5 V
• Product: Power Management Modules
• Silicon Manufacturer: ST Micro
• Silicon Core Number: VIPER12ADIP-E
• Kit Application Type: Power Management - Voltage Regulator
• Application Sub Type: AC / DC Adapter
• Kit Contents: Board
• Rohs Compliant: No
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With/related Products: VIPer12A
• Other names: 497-6413; STEVAL-ISA011V1

STEVAL-ISA011V1 Board Design
1.2
8/33
The conduction losses in the main switch depend on the VIPer12A I
resistance, and are expressed as:
Equation 9
Where,
P
r
Secondary Side
In order to select the output rectifier (secondary) diode D
maximum reverse voltage that the diode has to sustain, as well as the average and root
mean square of the current flowing through it (see
page 30
Equation 10
Where,
V
V
V
V
A commonly used selection method is to choose a diode with a 40% to 50% safety margin
from the value given by the V
margin of 20% to 30% if a standard “fast” diode is used. The safety margin prevents diode
breakdown from oscillation caused by circuit parasitic elements (e.g. transformer secondary
inductance leakage or parasitic diode capacitance) when the MOSFET is turned ON.
If the calculated V
the D
excellent choice for this application.
ds(on)
OUT
VIPer12A
R(max)
R
DC(max)
= reflected voltage, and
11
= output voltage,
= VIPer12A ON resistance.
= maximum reverse voltage,
value is about 34V. This makes the STPS340U (with 40V breakdown voltage) an
). V
= selected maximum input voltage.
= VIPer12A conduction losses, and
R(max)
R(max)
is calculated as follows:
is 23V and a Schottky diode is used (adding a 50% safety margin),
V
P
R(max)
R max
VIPer12A
calculation when a Schottky diode is used, or a safety
=
Rev. 1
V
=
OUT
r
ds on
+
V
------------------
V
O UT
R
I
STEVAL-ISA011V1 Schematic on
2
PRMS m ax
V
DC m ax
11
, the designer needs to know the
AN2272 - Application Note
PRMS(max)
and ON