ST AN1246 Application note
AN1246
Application note
VIPower: auxiliary BIAS
power supply using VIPer20A-E
Introduction
This application note describes a bias power supply to meet the needs of powering up
Power MOSFETs as well as providing standby power when the main unit is off.
The VIPer20ADIP-E, a part of STMicroelectronics proprietary VIPower (Vertical Intelligent
Power), is a current mode PWM with a 700 V avalanche rugged Power MOSFET. It uses a
fabrication process which allows the integration of analog control circuits with a vertical
power device on the same chip. It can provide an output of 10 W power capability for wide
range input, or 20 W for single input voltage range.
October 2007 Rev 4 1/8
www.st.com
Contents AN1246
Contents
1 Key features of the VIPer20ADIP-E . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2 General circuit description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
3 Connecting the demoboard . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
4 Layout considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
5 Burst mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
6 Performance and cost consideration . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
7 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2/8
AN1246 Key features of the VIPer20ADIP-E
1 Key features of the VIPer20ADIP-E
■ Adjustable switching frequency up to 200 kHz
■ Current mode control
■ Burst mode operation in standby mode, meets “Blue Angel” standards
■ Undervoltage lock-out with hysteresis
■ Integrated start-up supply
■ Avalanche rugged
■ Overtemperature protection
■ Primary or secondary regulation general circuit description
2 General circuit description
This demo board (see schematic in Figure 1) is a 110 to 375 VDC input discontinuous
flyback, working at 100 kHz. The output can deliver 12 V at 0.5 A continuous. This circuit
can be powered from the main bulk capacitors of an off-line power supply, power factor
correction output stage, or the AC line with the addition of a low current bridge rectifier. It
benefits from the EMI filter present in a typical power supply. The output uses a Schottky
diode for better efficiency. C7 is a low ESR capacitor which manages the ripple current. IC2
provides the reference and the feedback to tightly regulate the output. CS5, CS6, and RS3
form the feedback loop compensation to optimize stability during transients. The demoboard
can be tested with convection air. Depending on the final application, air flow might be
needed to keep the VIPer20ADIP-E under the thermal shutdown limit.
Figure 1. Schematic
CON
J1
2
1
F1
0.5 A Pico Fuse
R9
3.9
C12
220pF
1KV
D1
BYT11-600
C10
RS14
220pF
82K
1KV
RS4
DS3
1.6
LL4148
C2
4.7uF
400V
C3
120uF
16V
IC1
RS10
nu
8
7
6
drain
drain
drain
VIPer20ADIP-E
source
1
osc
2
vdd
3
45
compdrain
D4
NU
Cramer Coil CSM 1608-027
4
128T
3
2
14T
1
RS2
4.99K
CS4
3.9nF
T1
c9
2.2n
Y cap
CS5
33n
DS2
6
STPS1H100A
16T
7
CS6
.47u
RS3
5.1k
C7
680uF
16V
R6
150
12
43
IC3
H11A817A
IC2
TL431
R
A C
L2
10uH
R8
1.2k
R7
5.23k
CS11
47n
RS5
1.37k
C8
330uF
16V
J2
1
2
R11
CON
2.7k
3/8
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