Data Brief
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Rev 1
February 2006 1/5
5
STEVAL-ISA002V1
6W Single O utput Supply using VIPer12A
Features
QSwitch mod e General Purpose Po wer Supply
QInput: 85 to 264 VAC @ 50/60 Hz
QOutp ut: 12V @ 0.5A
QOutp ut power (peak): 6W
QBurst Mode Operation in Standby for Blue
Angel operation
QSwitching Frequency 60 kHz
Q75% Effi ciency
QAuxiliary Undervoltage Lockout with Hysteresis
QOutp ut Short Circuit Protection
QTherm al Shutdo wn Protection
QMeets EN55022 Class B EMI specification
Applications
This boa rd is an off-line wide range single output
general-purpose power supply capable of
delivering up to 6W of total output power. In low
load condition, it operates in the automatic burst
mode while in an overvoltage condition it will
operate in hiccup mode.
Other output voltages can easily be achieved by
changing the transformer and a few components
on the board, as shown in the application note.
Transformers are readily available for the
following configurations:
Q5V @ 1.2A
Q12V @ 0.5A
Q15V @ 0.4A
Q24V @ 0.25A .
Blue angels
When working in standby, the reference board
consum es less th an 1W t otal power cons umption
and t heref ore, m eets the “Blue A nge l” Norm . Th is
unit operates in burst m ode when the out put load
is reduced to zero and normal operation will
resume automatically when the power gets back
to a level higher than the standby power. The
output voltage remains regulated even when the
board operates in burst mode. The total power
consum ption mea sure d at 115Vac input with ze ro
load at output is approximately 168mW, while at
230Vac input this value is about 248mW. At
120Vac input, a minimum load of 52mA is needed
to keep t he input power consumpt ion at less than
1W.
STEVAL-ISA002V1
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General circuit description STEVAL-ISA002V1
2/5
1 General circuit description
This board is designed as a discon tinuous flyback regulator deliverin g 0.5A at 12V. The AC
input is rectifi ed and filtered by the bridge BR1, the bulk capacitor C1, and C2 to generate the
high voltage DC bus applied to the primary winding (pins 8-10) of the transformer, T R1. C1, L1,
and C2 provide EMI filtering for the circuit. R2 and C3 form the snubber circuit needed to
reduce the leakage spike and voltage ringing on the drain pin of VIPer12A. The output voltage
is regulated with a TL431 (U3) via an optocoupler (U2) to the feedback pin. The output voltage
ripple is controlled with the capacitor, C7, with an additional LC PI filter co nfiguration made up
of L4 and C8. It is possible to modif y the output voltages by changing the transformer turns ratio
and modi fyin g the resistance values of R6 and R7 in the feedback loop.
STEVAL-ISA002V1 Bo a rd S che m ati c
3/5
2 Board Schematic
Figure 1. Scheme
Revision history STEVAL-ISA002V1
4/5
3 Revision history
Date Revision Changes
01-Feb-2006 1 Initial release.
STEVAL-ISA002V1
5/5
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