AN1344
Application note
VIPower: 108 W power supply using VIPer100A-E
Introduction
The VIPer100A-E is designed to deliver 100 W for the upper voltage range or 50 W for
universal input. This application note describes a power supply that delivers over 100 W for
both voltage ranges using a voltage doubler in the front end. The VIPer100A-E combines a
state-of-the-art PWM circuit along with an optimized 700 V avalanche rugged Vertical Power
MOSFET. It is part of STMicroelectronics’ proprietary VIPower, (Vertical Intelligent Power). It
uses a fabrication process, which allows the integration of analog control circuits with
vertical power device on the same chip.
This document covers the implementation and results for achieving 18 V at 6 A power
supply that runs from both European and domestic mains. (90-132 V
ac
and 180- 264 V
ac
,
47-63 Hz).
October 2007
Rev 2
1/14
www.st.com
Contents
AN1344
Contents
1
2
Key features of the VIPer100A-E . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
General circuit description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.1
Transformer construction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
3
4
5
6
7
8
9
10
11
12
Layout considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Burst mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Thermal consideration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Overcurrent limiting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Transient response 50% step change . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Output ripple . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
EMI consideration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Performance and cost consideration . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
2/14
AN1344
Key features of the VIPer100A-E
1
Key features of the VIPer100A-E
■
■
■
■
■
■
■
■
Adjustable switching frequency up to 20 kHz
Current mode control
Burst mode operation in standby mode, meets "Blue Angel"
Undervoltage lock-out with hysteresis
Integrated start-up supply
Avalanche rugged
Overtemperature protection
Primary or secondary regulation
Board layout
Figure 1.
The power supply has low ripple voltage, good transient response, and be able to current
limit by power limiting and cycling on and off during a hard short. One use of this application
is to replace a bulky 60 Hz transformer with a lighter, better regulated, more efficient
alternative for an audio or entertainment system.
3/14
General circuit description
AN1344
2
General circuit description
The power supply has been designed for the upper voltage range. The lower voltage range
utilizes a voltage doubler to raise the bulk voltage to 2 times the peak of the input line
voltage. In the doubling mode, the current charges one capacitor for each phase of the line,
therefore doubling the voltage. When SW1 is open, both capacitors are charged in series
resulting in a bulk voltage equal to the peak of the line input.
A wire jumper can be installed at production for units destined for countries using the lower
range. The switching frequency operates at 100 kHz. The output can deliver 18 V from no
load to 6 A continuous. The mode of operation ranges from discontinuous at high line
minimum load to continuous at low line max load. This mode of operation was chosen to
minimize the high peak currents of the discontinuous mode of operation.
The VIPer100A-E can be regulated in secondary mode with an optocoupler giving excellent
regulation or in the primary mode. Primary regulation works by regulating the V
dd
pin at the
output of the auxiliary winding. Depending on the coupling of the transformer, a 15%
regulation can be achieved. In this application, by taking advantage of the dual regulation, a
current limit scheme is obtained. This VIPer100A-E advantage, along with the transformer
design, constitutes the overcurrent circuit. The transformer is designed for a turn ratio of
operation for a universal input and an inductance to run in continuous conduction mode at
one-half the output load. The coupling between the secondary to auxiliary winding along
with the VIPer100A-E dual regulation plays an important part in the current limit.
Under typical operation, the output is tightly regulated through U2 and U3, the optocoupler
and TL431 respectively. As the output current increases, it causes the voltage at the
auxiliary output to increase. R4 is selected to trim the voltage at V
dd
to reach 13 V when the
output current exceeds the maximum limit. At this point, primary regulation takes over and
the output starts to fold-back.
The output uses an STMicroelectronics 100 V Schottky diode for better efficiency. C9 and
C10 are low ESR capacitors which manage the ripple current. U3 provides the reference
and the feedback to tightly regulate the output. C7, C8, and R6 form the feed back loop
compensation to optimize stability during transients.
Table 1.
Electrical specification
Parameter
Input voltage
Output voltage J2
Load regulation (0.6 to 6 A) from set point
Line regulation (at max load)
Efficiency
Output ripple voltage
Input power at no load
Transient response, 50% load step
EMI
+/- 0.6%
+/- 0.05%
86% @120 V
DC
and 87% @ 375 V
DC
15 mV max
1.5 W typical
+/- 350 mV, +/- 1.9%, 200 µs settling time
EN55022 and FCC class B
Results
90-132 V
AC
with jumper in, 180 - 264 V
AC
no jumper
4/14
AN1344
Table 2.
R13
22
TX1
Cramer Coil
E34351E
5
.
1
.
9
Figure 2.
C16
.5W .001uf 1KV
D3
Parameter
Electrical schematic
Primary inductance
Core
Inductance rating (al factor)
BR1
F2
D5
BZW50-180
4
2
1
3
Primary leakage inductance
Transformer specification
Note
R3
200
2W
C4 100pF
1KV
4
2
.
.
.
18 V @ 6A
L4
10uH
7
STPS20H100C
T
CON2
2
1
J1
1
2
3
2
1
3
2
1
1
2
3
FUSE
2.5A
5X20mm
R12
470k
C17
.1uF
X CAP
2
4
C2
330uF
200V
D1
600V
STTA106
ST
C9
1800uF
25V
3
.
C10
1800uF
25V
C11
470uF
25V
J2
C1
.1uF
X CAP
R5
4.22K
1%
SW1
L1
1
2
600V 2A
BRIDGE
D2
1N4148
R4
8.2
R0
C14
CON
R1
33
Thermistor
2 X 6mH
SW SPST
Close for 120Vac
HS
1
2
3
OSC
VDD
DRAIN
6
0
2.2nF
Y1 cap
U1
VIPer100A-E
R8
10
C20
330uf
200V
4
5
SOURCE
COMP
C6
4.7nF
50V
C5
180uF
16V
C8
1uF
50V
R00
0 ohms
C15
.1uF
50V
R6
6.2K
4
1
R7
220
R9
1k
R11
20K
1%
R14
470k
U2
D4
NU
C7
22nF
50V
3
2
3
H11A817A
C12
.1uF
50V
U3
TL431
1
2
Value
7.9 µH
525 µH
ETD34
329 nH/T
Split primary - gapped core
General circuit description
R10
3.16K
1%
5/14
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