STEVAL-ISA011V1 STMicroelectronics, STEVAL-ISA011V1 Datasheet - Page 6

• 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
1.1.2
6/33
An acceptable value for V
Equation 2
Equation 3
Where,
f
The calculated value of C
and C2b, see
This means that C
electrolytic capacitor is usually around 20%.
Step 2, Transformer Selection
The next step is selecting a transformer with a Primary Inductance (L
system to work at the boundary between Continuous Conduction Mode (CCM) and
Discontinuous Conduction Mode (DCM). The worst case is minimum input voltage and full
load. This value is expressed as:
Equation 4
Where,
L
V
D
P
f
V
line
SW
MAX
T is expressed as:
T = the time between the two conduction cycles of the input bridge diodes, and
DC(min)
MAX
IN
R
= reflected voltage (fixed to 90V).
= line frequency.
= input power,
= switching frequency (internally fixed in the VIper12A to 60kHz), and
= maximum inductance for discontinuous mode operation,
= maximum duty cycle,
= selected minimum input voltage required for the flyback (converter) stage,
STEVAL-ISA011V Demo Board Schematic on page 30
IN
= 20µF. This value was selected because the tolerance for an
L
MAX
T
IN
DC(min)
V
DC min
=
using
------------------------- -
2
=
------------------------------------------------------------- -
V
is 80% of V
1
Equation 1
DC min
f
=
2 P
line
Rev. 1
0.8V
IN
AC min pk
D
f
–
SW
AC(min)pk
M AX
is 16µF. For the board, two capacitors (C2a
arc
cos
2
⇒
=
:
⎛
⎝
L
-----------------------------
V
MAX
V
2V
AC m in pk
DC min
AC min
=
3.5mH
AN2272 - Application Note
⎞
⎠
) of 10µF were used.
P
) that allows the